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SUSITNA HYDROELECTRIC PROJECT
APPENDIX 8.9
RIVER MORPHOLOGY
JANUARY 1982
PREPARED FOP.•
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L----_ALASKA POWF.~R AUI~HORrr~y--·~-=-~-=-.J
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
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APPENDIX 8.9
RIVER MORPHOLOGY
~JANUARY 1982
Prepared for:
ACRES AMERICAN INCORPORATED
1000 Liberty Bank Building
Main at Court
Buffalo 1 New York 14202
Telephone (716) 853-7525
Prepared by:
S. Bredthauer & B. Drage
R&M CONSULTANTS, INC.
P .0. Box 6087
5024 Cordova Street
Anchorage 1 Alaska 99503
Telephone (907) 279-0483
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
TASK 3 -HYDROLOGY
SUBTASK 3.07 & 3~ 10 -CLOSEOUT REPORT
RIVER MORPHOLOGY STUDIES
TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
1 -INTRODUCTION
1·.1 -Background and Purpose of Study
1 • 2 ... Downstream Effects
1.3 -Report Contents
2 -SUMMARY
2.1 -Basin Overview
2.2 -Projected Post Project Morphological Changes on
the Downstream River
3 -FLOW REGIME
3.1 -Flow Duration Analysis (Pre:-Project Conditions)
3.2 -Post-Project Flows
3. 3 -Contribution by Tributaries
3.4 ·.. Flow Variability Index
4 -SEDIMENT REGIME
4.1 -Suspended Sediment
4. 2 -Bedload
4.3 ... Reservoir Trap Efficiency
4.4 -Bed Material Movement
4.5 -Contribution of Sediment Downstream
- i -
s
iii
vii
1-1
1-1
1-1
1 ... 3
2-1
2-1
2.-3
3-1
3-1
3-2
3_;4
4-1
4-1
4-1
4-2
4-3
4-5
0
5 ... REGIME ANALYSIS
5.1 ... River Response Rele!tionships
5 .. 2 -Rjver Pattern and Channel Characteristics of Natural
System
5. 3 Regime Analysis of Susitna River Reaches
6 -SIDE CHANNELS AND SLOUGHS
6~ 1 -Present and Projected Flow Regime
6.2 -Expected Changes
7 -ICE PROCESSES
7.1 -Pre-Project Ice Conditions
7.2 -Post-Project Ice Conditions
BIBLIOGRAPHY
APPENDIX A -RATING TABLES
APPENDiX B -FLOW VARIABILITY RAT10S
APPENDIX C -WATER SURFACE ELEVATIONS
-jj ...
Page
4
5-1
5-1
S-2
5-4
G-1
"' 6-1
6-1
7-1
7-1
7-3
Figure No~
2.1
2.2
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12
LISl' OF FIGURES
Susitna River basin
Susitna River cross-section locations
Flow duration curves .. Susitna River at Denali,
Cantwel.!, Gold Creek
Flow dur·ation curves -MacLaren River
Flow duration curves -Chulitna and Talkeetna
Rivers
Flow duration curve -Susitna River at Susitna
Station
Pre-and post-project flow duration curves,
Susjtna River at Gold Creek
Pre-and post ... project flow duration curves,
Susitna River at Sunshine
Pre-and post-project flow duration curves 1
Susitna River at Susitna Station
Annual flow duration curves at Susitna ... Chulitna-
Tall<eetna confluence
Pre-and post-project discharge-stage frequency
curves, Susitna River at Gold Creek
Pre-and post-project discharge-stage frequency
curves 1 Susitna River at Sunshine
Pre-and post-project discharge-stage frequency
curves 1 Susitna River at Delta I stands
Pre-and post-project discharge-stage frequency
curves, Susitna River at Susitna Station
Design. dimensionless regional frequency curve
annual instantaneous flood peaks
-iii -
Page
2.-7
2-8
3-26
3-27
3-28
3-29
3-30
.3-31
3-32
3-33
3-34
3-35
3-35
3-38
LIST OF FIGURES -(Co .. ttinU«;~d)
Figure No.
4.1
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12.
4~13
5.1
5.2
Title
Suspended sediment rating curves -Susitna
River at Denali and MacLaren River near
Paxson
Suspended sediment l"'ating curve-Susitna River
near Cantwell (Vee Canyon)
Suspended sediment t"ating curve-Susitna River
at Gold Creek ·· .
Suspended sediment ratir.g curves, Chulitna and
Talkeetna Rivers
Suspended sediment rating curve, Susltna River
at Susitna Station
Annual suspended sediment load duratR;n curves
Estimated bedload rating curve, Susitna River
at Denali
Bed material movement curves, LRX-54, -57,
-62, -68
Bed material movement curves, LRX -43, -45,
-49, -so, -s1
Bed material movement curves, LRX -36, -38,
-39, -40
Bed material movement curves 1 L.RX -28, -2H,
-31/ -35
Bed material movement curves, LHX -16, -18,
-20, -24
Bed material movement curves, LRX -4, ... 7, -9,
-12
Single-channel river pattern
Split channel river pattern
.. iv -
Page
4-19
4-20
4-21
4-22
4-23
4-24
4-25.
4-26·.
4-27
4-29
4-.30
4-31
5-22
5-23
LIST OF FIGURES -(Continued)
Figure No.
5.3
5.4
5.5
5.7
5.8
5.9
5.10
5.11
5 .. 12
5 .. ,3
5 .. 14
5.15
5.16
5.17
5.18
5.19
5.20
5~21
Title·
Braided channef river pattern
Multi -channel river pattern
River profiles, Susitna River and tributaries
above Sunshine
River profiles, Susitna River and tributaries
below Sunshine
Susitna River reach RM 149 to RM 144
Cross-section, RM 148.7
Susitna River reach RM 144 to RM 139
Cross-section, RM 141 . 5
Susitna River reach RM 139 to RM 129.5
Cross-section, RM 134.7
Susitna River reach RM 129.5 to RM 119
Cross-section, RM 121.6
Susitna River reach RM 119 to RM 104
Cross-section, RM 108.4
Susitna River reach RM 104 to RM 95
Cross-section, RM 101.5
1951-1980 aerial photo comparison, Susitna-
Chulitna-Talkeetna confluence
Susitna River reach RM 95 to RM 61
susitna River reach RM 61 to RM 42
- v -
5-24
5-25
5-26
5-27
5-28
5-29
5-30
5 .. 3,
5-32
5-33
5-34
5-35
5-36
5-37
5-38
5-39
5-40
5 .... 41
5-42
LIST OF FIGURES ... (Continued)
Figure No.
5.22
5.23
5.24
6.1
Title
Synthesized crass-section, Delta I stands
1951-1980 aerial photo comparison, Susitna-Deshka
confluence
1951-1980 aerial photo comparison, Susitna-Yentna
confluence
Susitna River overflow channels
-vi -
Page
5-43
5-44
5-45
6-6
Table No.
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12
3.13
3.14
3 15
LIST OF TABLES
Title
Period of record, Susitna streamgaglng stations
Susitna River at Gold Creek, pre-project
monthly flows
Susitna River at Sunshine, pre-project monthly
flows
Susitna River at Susitna Station, pre-project
monthly fJows
' .
Susitna River at Gold ·creek1 •· post-project
monthly flows (Case A)
Susitna River at Sunshine, post-project monthly
flows (Case A)
Susitna River at Susitna Station, post-project
monthly flows (Case A)
Sus~tna River at Gold Creek, post-project
monthly flows (Case D)
Susitna River at Sunshine, post-project
monthly flows (Case D)
Susitna River at Susitna Station, post-project
monthly flows (Case D)
Relative contribution of flows at Susitna-Chulitna-
TaJ keetna confluence (pre-project)
Relative contribution of flows at Susitna-Chulitna-
Tal keetna confluence (post-project, Case A)
0
Relative contribution of flows at Susitna-Chulitna-
Tatkeetna confluence (post-project, Case D)
0
Pre-and post-project discharge and stage
frequency analysis
Lower Susitna River basin characteristics for
mean annaul flood calculations
-vii -
P._age
3-6
3-7
3-8
3-9
3-10
3-11
3-12'
3-13
3-14
3-15
3-16
3-17
3-18
3-19
3-20
LIST OF TABLE -(<;ontinued)
Table No.
3.16
3.17
3.18
.3 .. 19
3.20
3.21
4.1
4.2
4.3
4.4
4.5
4.6
5.1
6.1
6.2
6.3
7.1
7.2
Title
Monthly average ratios, (1-day high and low flow)/
(monthly flow)
Monthly average ratios, (3 .. day high and low flow)/
(monthly flow)
Monthly average rati.os, (7-day high and low flow)/
(monthly flow)
Monthly average ratios 1 (15-day high and 14-day
low flow)/(monthly f_low)
Ratios of annual 1-, 3-, 7-1 14-, 30-1 60-and
90-day l,aw flows to annuaf low monthly ffows
Average monthly spill below Devil Canyon Dam
Suspended sediment rating equations
Bedload transport data, 1981
Bed material size distribution anaiysis
Average velocities at selected cross-sections
Susitna River profile data summary
Sediment sources downstream of Devil Canyon
Susitna River reach definitions
Location of blocked and partially-blocked
side-channels
Water surface elevations in multiple channels
at low flow (below 10,000 cfs)
Water surface elevations in multiple channels
at 22,200 cfs
Locations of ice accumulations during freezeup
-1980
lee jam locations during breakup 1 May, 1981
-viii -
Pag~
3-21
3-22
3-23
3-24
3-25
3-26
4-6
4-7
4-8
4 ... 9
4-10
4-13
5-21
6-3
6-4
6-5
7-4'
7-5
--
•• ~,, ... > ---· ·-··~-_,_
1 -INTRODUCTION
1.1 Background and Purpose
Construction of dams at Watana and Devil Canyon will effect the
river morphology downstream of Devil Canyon, with possible
effects on fisheries, vegetation, and wildlife. The possible effects
of dams on river morphology are described below. The pUrpose of
this report is to describe the existing flow, sediment and river
regimes from Devil Canyon to the mouth of the Susitna River, and
to assess potential morphological changes in the river.
1.2 Downstream Effects of Dams
The construction of dams on a river system modifies both the
natural flow regime and the natural sediment transport regime,
thus impacting the river processes downstream of the dams ..
Be1Fore discussing the· impacts on the river morphology of the
Su:sitna River downstream of Devil Canyon 1 a summary of impacts
downstream of similar projects is worthwhile.
Kellerhals and Gill (1973), Petts (1977), Taylor (1978) and Baxter
and Glaude (1980} have summarized channel response to flow
re,gulation. Operation of reservoirs significantly alters the flow
regime. There is often an increase in the diurnai variation of flow
due to the variation in the amount of water passing the turbines in
order to follow the load demand. Annual peak discharges are
re:duced not only due to storage which aHows no overflow over the
spillway, but also due to the surcharge storage provided by the
rise. in water level above the spillway crest. Routing through a
re~servoir with no availabie storage may reduce some flood peaks by
over 50% (Moore 1 1969) 1 depending on the characteristics of the
spillway, reservoir 1 and flood hydrograph. The magnitude of the
mean annual flood of the Colorado River below Hoover Dam has
been reduced by 60% (Dolan, Howard, and Gallenson, 1974).. The
t•:>tal volume of flow may be reduced due to the increase in time
during which seepage and evaporation losses may occur. Base
flow tends to be increased due to seepage and to minimum releases
to the channel below the dam.
Heservoirs with a large storage capacity may trap and store over
95% of the sediment load transported by the river (Leopold,
Wolman' and Miller, 1964) I with the actual percentage depending
primarily on the storage capacity-inflow ratio (Brune, 1953),
although reservoir shape, reservoir operation, and sediment
characteristics have some influence (Gottschalk, 1964).
The effect of dams on the sediment load must not be considered in
isolation but in relation to changes in river sediment transport
capacity, to river regime, to channel morphometry 1 and with
.r5/a 1 - 1
regard to major tributaries. At tributaries which transport large
quantities of sediment into :1 regulated mainstream with reduced
flows and consequently less ability to flush away sediments, the
effects include aggradation, an increase in bed s!ope of the
tdbutary, and trenching of the deposit to form a channel that is
in quasi-equllibr"ium with the ftow regimt: (King, 1961; Kellerhafs,
Church and Davies, 1977). The increased gradient results in
increased velocities, bank instability, possible major changes in the
geomorphic character of the tributary stream, and increased local
scour (Simons and Senturk, 1976).
All of the bedload enter!ng a reservoir is deposited in the
reservoir. This reduction in sediment supply is usually greater
than that in sediment-carrying capacity 1 resulting jn erosion
downstream of the dam exc;:ept where an armor layer or an outcrop
of bedrock occurs (Petts, 1977). Degradation will occur where the
regulated flow has sufficient tractive force to initiate sediment
movement in the channel (Gottschalk, 1964). Once the channel
bed has been stabilized, either by armoring or by the exposure of
bedrock, then the banks, which usually consist of finer material
than the bed, begin to fail and the channel will widen. Where
armoring or bedrock occur across the width of the channel, a
simple adjustment will occur where streamflow is accommodated in
the existing channel.
The sediment load plays an important role in the process of
meander migration across alluvial plains by forming point bars from
bed load deposition on the inside bank. These point bars are then
aggraded to floodplain levels due to the deposition of suspended
sediment in the emerging vegetation. The reduction in sediment
load may disrupt this process, with at least local ecological
changes. Widening of channels at meander bends and. lateral
instability may also be expected (Kellerhals and Gill, 1973).
Maximum degradation normally occurs in the tailwater of the dam,
but may extend downstream. Rates of degradation up to 15 em
per year have been observed both in the United States (Leopold,
Wolman, and Miller1 1964) and Europe (Shulits, 1934). Channel
adjustment to bed degradation and the associated reduction in
slope was observed for nearly 250 km below Elephant Bu~e Dam
(Stabler, 1925). When an armored condition occurs where the
river is unable to recharge itself to capacity, the river may pick
up additional material downstream, as was observed on the
Colorado River below Hoover Dam (Stanley, 1S31).
The channel properties of gravel-bed rivers such as the main stem
of the Peace River in Alberta appear to be controlled by floods
with a recurrence interval of 1. 5 to 2 years (Bray, 1972) ~
Regulation reduces these flows 1 effectively reducing the size of the
gravel-bed river without immediately changing the channel, but
certain channel properties will adjust to the channel regime over a
rS/a 1 - 2
longer period of time. On the Peace River, the entrenched layer
of the channel 1 the proximity of bedrock, and the resistant bed
material preclude significant changes in width and depth
relationships or in the slope (except near tributary junctions), but
deep scour holes at bends will fill to som~ degree 1 and gravel bars
exposed above the new high water mdrk will have emerging
vegetation (Kellerhals and Gill, 1973).
Vegetation encroachment on the higher elevations of the gravel
bars downstream of a dam can be expected due to the reduced
summer streamflows and the lower flood peaks, and in time could
encroach on present high water channels (Tutt, 1979; KeiJeri)als,
Church and Davies, 1977). The effect of the additional vegetation
would be to increase the channel roughness 1 thus decreasing, the
channel water conveyance~ The channel size and capacity could
gradually decrease d~e to vegetation encroachment, deposition of
suspended load in the newly . vegetated areas, accumulation of
material from the valley walls and deposition of sediment brought
in by the tributaries. During periods of high flow 1 higher river
stages could be expected.
The W. A. C. Bennett Dam on the Peace River had a dramatic
unplanned impact on the Peace-Athabasca Delta (Baxter and
Glaude, 1980). The delta is a series of marshes interspersed with
lakes and ponds of various sizes. Before the dam was built, the
delta was maintained in this state due to almost annual flooding 1
which prevented vegetation typical of drier ground from being able
to establish itself. The hydrological situation itself was complex.
The Peace River, passing to the north of the delta, contributed
little to the actual flooding, but its flood waters blocked the exit
of the Athabasca River 1 which entered from the south and caused
the actual flooding. After cor:.struction of Bennett Dam_. the delta
starte·d drying up, with dry· ground vegetation establishing itself.
The effect of the dam was initially obscured due to lower than
normal precipitation for some years previously, but it was
eventually concluded that the dam was at least a contributing
factor, as flood levels on the Peace River were lowered 1 resulting
in the Peace River no longer blocking the exit of the Athabasca
River.
1. 3 Report Contents
A relatively significant amount of data are available for the reach
of river between Devil Canyon and Talkeetna. Over 30 years of
streamflow and suspended sediment data are availabfe for the
Susitna River at Gold Creek. Aerial photography was flown in
1980 1 and blueline copies made at a scale of 1 11 = 500 1 •
Cross-sections were surveyed at 66 sites from Devil Canyon to the
Chulitna confluence. Bed material data were gathered at a number
of cross-sections~ Using crest gage data gathered in this reach,
the HEC-2 wa:ter surface profile model was calibrated, and water
rS/a 1 - 3
surface elevations estimated using results from the model. Ice
conditions were observed during the 1980-81 winter and 1981
freeze ... up.
The available data base is considerably smalle·r below Talkeetna.
Streamflow, suspended sediment and water quafity data have been
gathered at the. Susitna Station gaging site since 1975.. Streamflow
suspended sediment and bedload data were collected at Sunshine
(Parks Highway Bridge) in 1981. Aerial photography is available
at a scale of 1 u = 500'. Cross-sections are available only at U.S.
Geological Survey gaging sites and at miscellaneous sites or
sloughs along the river. Ice conditions were observed during the
1980-81 and 1981-82 winters.
This report compiles, pre'sents and interprets all available
information pertinent to . assessing changes in the river
morphology. The existing river patterns and controlling features
are described from Devil Canyon to Cook l nlet. A qualitative
assessment is also made to predict the response of the river to
post-pr9ject conditions.
rS/a .. -... --1 - 4
2-SUMMARY -
2.1 -Basin Overview
The Susitna River drainage basin is located in the Cook Jnlet
subregion of the southcentral ·region of Alaska. The drainage
basin covers 19,600 squar·e miles. It is bordered on the west and
north by the Aiaska Range, on the east by the Talkeetna
Mountains and the Copper River lowland, and on the south by
Cook Inlet. ·
Climate
The upper drainage basin is in the continental climatic zone 1 and
the lc..wer drainage basin is in the transitional climatic zone. Due
to the maritime infll.{ence and the lower. elevations, temperatures
are more moderate and precipitation is Jess in the lower basin than
. that in the upper basin. In the higher regions, freeze-up starts
in early October 1 and most rivers are ice-free in fate April or
early May.
Topograph)!:
Tributaries in the western and northern portions of the drainage
basin rise in the glaciers of the Alaska Range 1 which is dominated
by Mount McKinley (20,320 feet) and Mount Foraker. Other peaks
average 7,000 to 9,000 feet in altitude. Those in the eastern
portion rise in the Copper River lowland and in the ·Talkeetna
Mountains. The highest peak is 8,850 feet, with elevations
averaging 6,000 to 7,000 feet and decreasing northward and
westward. To the northwest, the mountains form a broad, roiling
glacially scoured upland dissected by deep glaciated valleys.
Between these ranges and the Cook Inlet is the Susitna lowlands 1;
a broad basin increasing in elevation from sea level to 500 feet,
with local relief of 50 to 250 feet.
Geology
The Susitna River basin derived its present geologic features
during Quaternary glaciations. The underlying bedrock consists
of granitic batholiths intruded into Paleozoic and Mesozojc volcanic
and sedimentary rocks on the south side of the Alaska Range and
in the Talkeetna Mountains. Copper, gold, silver, and other
minerals are associated with the intrusions. The unconsolidated
deposits of the lowJands, which contain thaw lakes and marshes
and are poorly drained, overlay Tertiar·y coal-bearing rocks
resting on Mesozoic rocks 30,000 feet thick.
Unconsolidated deposits are extensive and largely derived from
glaciers. Glacial moraines and gravels fill glacial-carved U-shaped
valleys in the upland ar.eas. Glaciolacustrine deposits are present
r31/b 2 - 1
in the lowlands. During the periods of glaciation·, convergence of
g1ac1~1 flow blocked drainage, and preglacial lakes formed. The
deposits are laminated, rhythmically bedded sand, silt, and clay.
Fluvial deposits are present in the major river valleys 1 and consist
of gravels and sands.
The drainage basin lies in the discontinuous permafrost ZOI:'Je. Jn
th.e mountainous areas, discontinuous permafrost is generally
present. In the lowlands and upland areas below 3 1 000 feet, there
are isolated masses of permafrost in areas of predominately
· fine-grained deposits. Permafrost does not exist in coarse-grained
deposits or in deposits adjacent to the main stem river or large
water bodies.
Soils
Gravelly till and outwash in th~ lowlands and on upland slopes are
overlain by shallow to moderately deer:> silty soils. Windblown silt
covers upland areas. Steeper upper slopes have shallow,· gravelly
and. loamy deposits with many bedrock exposures. On the south
fJank of the Alaska Range and south-facing slopes of the Talkeetna
Mountains, soils are wel!-drainedJ dark, and gravelly to loamy"
Poorly drained, gravelly and stony loams with permafrost are
present on northfacing slopes of foothills, moraines, and vaHey
bottoms. Water erosion is moderate on low slopes and severe on
steep slopes.
Vegetation
Vegetation above tree line in steep, rocky soils is predominately
alpine tundra. Well-drained upland soils support white spruce and
grasses, whereas poorly drained valley bottom soils support
muskeg. Tideflats are dominated by sedge meadows where
drainage is poor, and are bordered by moist tundra grading into
spruce-hardwood forests in well-drained loamy soHs.
Water Resources
The Susitna River drainage basin is the sixth largest system in
Alaska. The Susitna River is 320 miles long, and major tributaries
include the Yentna, Chulitna, and Talkeetna Rivers. Extensive
glaciers in the headwaters ·contribute substantial suspended
sediment loads during summer months. Streamflow is characterized
by high flows between May and September and low flows from
October to April. High summer discharges are caused by snowmelt1
rainfall, and glacial melt. Tributaries are generally turbulent in
the upper reaches and slower flowing in the lower reaches.
On the western side of the basin is the Yentna River 1 with its
tributaries the Skwentna River (entering"' on the southwest) and
the Kahiltna River (entering on the northwest). The Yentna River
r31/b 2-2
rises in the glaciers of the Alaska Range and flows 95 miles
southeasterly 1 entering the Susitna River 28 miles from its mouth.
The Chulitna River rises in the gtaciers on the south slope of
·Mount McKinley and flows 90 miles south 1 entering the Susitna
River near Talkeetna. The Talkeetna River rises in the Talkeetna
Mountains 1 flows west, and also enters the Susitna River near
Talkeetna, 97 miles from its mouth. The Susitna River and its
major downstream tributaries are shown in Fjgure 2.1.
Cross-section locations on the river between the Parks Highway
and the proposed Watana Dam are illustrated in Figure 2. 2.
2.2 Projected Post Project Morphological Changes on the
Downstream River ·
The following summarizes potential changes in the current river
morphology that could · be expected from flow and sediment
regulation.
The Susitna River main channel between Devil Canyon and the
Chulitna River confluence will tend to become more defined with a
na·rrower channel. The main channel rh~~~ pattern wil! strive for a
tighter, better defined meander patterra ·.vi thin the existing banks.
A trend of channel width reduction by encroachment of vegetation
and sediment deposition can be expected. This will tend to
gradually increase flow depths at specific discharges above the
immediate post-project condition.
Downstream of the Susitna-Chu1itna confluence the frequency of
occurrence of dramatic changes in river morphology will decrease
under post-project conditions, resulting in a more stabilized
floodplain, decreased number of subchannels and increased
vegetative cover. However, it must be recognized that an extreme
flood generated by either the Chulitna River 1 Talkeetna River or·
both in combination with other tributaries could mask this process
and delay observable changes far several years.
The project morphological changes for specific river reaches are
summarized below:
RM 149 to RM 144
0
0
r31/b
The channel is stable and little change in form is
expected.
Portage Creek fan will progress out into the Susitna
until equilibrium with the regulated Susitna stage is
established. Perching of the stream mouth is not
. expected.
2 -3
RM 144 to RM 139
0
0
0
0
0
Erosion of valley walls and terraces will decrease
dramatically due to the armour layer.
Reworking of alluvial deposits in the main chann~l will
continue but at a reduced rate.
Main channel form will pr·ogress slowly to a more uniform
sinuous pattern.
Subc:-~~nnels may become inactive ..
Tributary at RM 144 could become perched. It may not
be able to regrade its coarse bed sediments to meet the
regulated Susitna water level.
RM 139 to RM 129.5
0
0
0
0
0 .
0
Indian River will continue to extend its alluvial deposits
into the Susitna. Indian River should easily grade its
bed to meet the regulated Susitna Stage.
Gold Creek gradient is p!"'esently very steep as it enters
the Susitna. The cobble and bouider bed will resist
regrading the bed to meet the regulated Susltna stage.
Fourth of July Creek gradient is currently relatively flat
and should easily adjust to the regulated Susitna stage.
Erosion of valley walls 1 terrace deposits and alluvial
banks will reduce dramatically due to the armour layer.
Reworking of active gravel bed materials will continue at
a reduced rate. Main channel form will slowly progress
to a more uniform sinuous pattern.
Several of the sloughs and subchannels could be blocked
off from the Susitna main channel at the regulated stage.
Where these channels rejoin the Susitna 1 gradual siltation
and vegetation encroachme!')t will occur.
RM 129.5 to RM 119
0
0
Erosion of valley walls 1 terraces and .alluvial deposits will
reduce dramatically~
At RM 128 and 125.5, reworking of gravel bed material
will continue, but at a reduced rate. Main channel form
will become more uniform.
2 -4
0
0
Cobble berms at the side channels and sloughs '"~~Hl
control and perhaps block main channel flow from
entering them.
The river should continue its preferred and stable route
along the west valley waiL
RM 119 to RM 104
0 No consequential changes in the channel morphology are
expected.
RM 104 to RM 95
0
0
0
Chulitna River will continue to expand and extend its
alluvial dep~osits. Decreasing the summer flow magnitude
in the Susitna River. will allow the Chulitna to extend
alluvial deposits to the ea·st and south. This could
induce erosion of the east ban kline towards the rail road ..
Increased deposition at the confluence will cause
backwater uLi the Susitna River. Lateral instability will
continue after the project.
The Talkeetna River will maintain the ability to create its
channel into the Susitna system. No consequential
interactions can be foreseen at this time.
RM 95 to RM 61
0
0
r31/b
Under post-project conditions, the bankfull flood (mean
annual flood under pre-pr~Jject conditions) could be
expected to have ·a recurrence interval of once every
five to ten years. This will tend to decrease the
frequency of occurrence of both bed material movement
and consequently of changes in braided channel shape,
form and network.
Over a long period, a trend towcH"ds relative stabilization
of the floodplain features should occur. The main
channel and major subchannefs could progress to a more
uniform meandering pattern. The active gravel
floodplain may develop a vegetative cover and the minor
subchannels become relatively inactive. It must be
recognized that an extreme flood generated by either the
Chulitna River, Talkeetna River, or both, could mask
this process and delay observable changes for several
years.
2 - 5
RM 61 to RM 42
0
0
The Delta Island reach is a very complex and unstable
channel network. There exists a very broad floodplain
filled with varying channel types. Project induced
changes in flow and sediment regime reahzed at this
reach will be diluted by contribution from tributaries and
by the Susitna satisfying its sediment load by reworking
the wide floodplain alluvial deposits. Basic changes in
the overall channel network are not expected.
Local changes could occur in the main channel lateral
position but basic channel geometry should remain
relatively similar. To quantity post project morphology
changes with respect to the natural system would be
extremely d]fficult, if not impossible.
RM 42 to RM 0
0
r31/b
Effects of the project on river morphology through this
reach of river would be extremely difficult ·or impossible
to quantify. The dilution effect of major and minor
tributaries as well as the balancing of changes by the
Susitna River system should mask any measurable
changes that could occur as a result of the project for
several decades.
2 - 6
PREPARED . BY I
R&M CONSULTANTS, INC.
DEVILS CANYON
• GOLD CREEK
SUNSHINE
STATtON
LOCATION MAP
LOWER SUSITNA RIVER
SUSITNA:RIVER BASIN
RIV~R
PREPARED FOR:
2-7 FIGURE 2.1
.,
N
I
00
1--·-----
1 1/2 0
MILES
9
2 3
PI.ATE ..2_
t--Pr_.e~p_ar_ed_b..;;.Y: .... : _____________ ,.,_, ____________ _... _______________________ Pr_ep~ar=e=d=£::o:=r
• FIGURE 2.2 RIVER CRC.,SS-SECTION LOCATIONS
A~~f~ ~==========~---~---------------------·------------------------~~==
R&M CONSULTANTS. INC.
.,
Prepared by:
' •.
-
./
R&M CCNSUL,.ANTS, INC::.
--
1 1/2 0
---·--liSR
MILES
r--=; 1
1 2 3
ared for:
FIGURE2.2 CONTINUED
-
N
I
1-'
0
--
R&M CONSULTANTS. INC.
-·-·---
1
I
2
-
. . . I
3
FIGURE. 2.2 CONT5NUEO
..-.-
.' r:
------- ----
" .... --.--~~-·r•·---------· ... • ....
; I
~\
. (
PlATE 7
to6
MiLES
4= 9
1 2
I
!
I
Prepared by:
FIGURE 2.2 CONTINUED
3 -FLOW REGIME
The flow regime defines the amount of tim'~ that certain flows,
together with the corresponding hydraulic characteristics, can be
expected. The information is useful in analysis of the sediment
regime and the river morphology, as most of the sediment
transport occurs at high flows. lt is also important in evaluating
the impact of flow regulation on fisheries.
3.1 Flow Duration Analysis
A flow duration curve shows the propor-tion of time that discharge
equals or exceeds various values. Pre-project monthly and annual
flow duration curves based on average daily flows· were developed
for the four 111ainste1J1 Susitna River gaging stations (Denali, Vee
Canyon, Gold Creek and Susitna Station) and three major
tributaries (MacLaren, Chulitna, and ·TaJ keetna Rivers), and are
shown on Figures 3.1 through 3.4. The p~riod of record used for
each flow duration curve is shown in Table 3.1. The curves do
not necessa~ily indicate that flows are greater than a given value
for .a certain number of days for every year, Le. that 30,000 cfs
is exceeded five percent of every year at the Susitna River at
Gold Creek. In the above example, the flow duration curve
indicates only that five percent of all days during the period of
record had discharges above 30,000 cfs. The annual flow duration
curve does not indicate how the sequence of flows occur -annual
hyd_rographs should be examined to determine sequences of high or
fow flows.
The shape of the monthly and annual flow duration curves are
similar for each of the stations. The flow duration curves are
indicative of flow from glacial rivers. Streamflow is low in the
winter months, with little variation in flow and no unusual peaks.
Flow begins to increase slightly in April as breakup approaches.
Peak flows in May are an order of m&gnitude greater than in
April. Flow in May also shows the greatest variation for any
month, as low flows may continue into May before the high
snowmelt/breakup flows occur. June has the highest peaks and
the highest median flow. The months of June through July have
relatively flat flow duration curves, indicating that significant
portions of flow are within a relatively narr·ow flow range. More
variability of flow is evident in September and October as cooler
weather becomes more prevalent ..
3. 2 Post Project Flow;5
Daily post-project flows for the Susitna River below Devil Canyon
are not available. However, the change in flow durations can be
estimated based on monthly fiow duration curves. Due to the lack
r31/c 3 - 1
of records at Sunshine and the short period of record at Susitna
Station, 30 years of pre-project monthly flows were synthesized
using records from the Susitna River at Gold Creek, Talkeetna
Rjver, and Chulitna River gaging stations~ The post-project
project flow duration curves are based on the 30-year monthly
operation of the Watana and Devil Canyon Reservoirs for Case A
(optimal power operations) and Case D (minimal impact on salmon
spawning areas in side channels and sloughs above Talk,~etna).
Tables 3.2 through 3.10 present the 30-year record of hi~itorical
and synthesized monthly flows for pre-and post-project conditions
at Susitng River at Gold Creek, Sunshine and Susitna Station.
Annual and monthly flow duration curves for pre-and post-project
conditions for these stations are shown in Figures 3. 5 through
3. 7. Also presented on these figures are the correspondinrJ water
surface elevations, based on USGS rating curves. For the ice
cover period between_ November and early May, the water surface
elevations shown on the graphs. will not be valid. The only reason
for their inclusion is that the difference in water levels under pre-
and post-project conditions is likely to be of the same order as
under open water conditions.
The relativa contribution of average monthly flows at the
confluence of the Susitna, Chulitna and Talkeetna Rivers is shown
in Tables 3.11 through 3.13 for pre-and post-project conditions.
The annual flow duration curves for the three rivers, including
both post-project flow options for Susitna, are illustrated together
an Figure 3. S.
The pre-and post-project annual flood frequency curves for the
Susitna River at Gold Creek, Sunshine1 Delta Islands, and Susitna
Station are presented in Figures 3. ~' through 3.12. Table 3.14
presents pre-and post-project flood discharges and stages for the
four sites.
Rating tables and rating curves for the above three sites. are
presented in Appendix A.
3.3 Contribution by Tributaries
As part of Subtask 3 .. 05 -Flood Studies, a regional equation was
developed to determine mean annual flood flows based on basin
characteristics. A forward stepping multiple linear regression
computer program was utilized. Twelve watershed parameters were
considered, including: drainage area 1 m:1in channel slope, stream
length 1 mean basin elevation, area of lakes and ponds, area of
forests, area of glaciers, mean annual precipitation, precipitation
intensity, mean annual snowfall, and mean minimum January
temperature. The most influential parameters in predicting the
mean annual instantaneous peak flow are drainage area, stream
length, area of glaciers, mean annual precipitation, and mean
annual snowfalL
1'"'31/c 3 - 2
I
I
I
r
The resulting equation was selected as being the most
representative for determining the mean annual instantaneous peak
flow:
Where:
Q = 7.06 (D.A.) + 46 .. 36 (L) + 697.14 (G)+
D.A.
L
G
MAP~
MAS
200.15 (MAP) -49.55 (MAS) -2594
Drainage Area (mi 2 )
Stream Length (mi)
Percent of Dr·ainage Area Covered by Glaciers(%)
Mean Annual Precipitation (in)
Mean Annual Snowfall (in)
Table 3.15 lists a summary of · basin characteristics at various
locations along the lower Susitna River that were used in this
study to determine fl.ood flows. It Is interesting to note the
·variance that exists within the Susltna basin. For example, the
two major western tributaries, the Chulitna and Yentna Rivers,
have the highest percentage of glacial area. Susitna River at Gold
Creek has the lowest percentage of forested area. Table 3.15 is a
good reference for general comparison of basin characteristics.
The mean annual· instantaneous peak was used in conjunction with
Figure 3.13, the design dimensionless l"egional frequency curve .for
the Susitna River basin. Thte annllal instantaneous peak for
selected return periods was determined by multiplying the
appropriate dimensionless curve value by the mean annual
instantaneous peak determined from the above equation. This
procedure, was used to determine pre-project flood frequencies at
ungaged ·sites along the Susitna River.
Additional discussion of the regional flood frequency analysis can
be found in the Regional Flood Peak and Volume Frequency
Analysis: Closeout Report (R&M, 1981b).
3.4 Flow Variability Index
Long-term average monthly pre-and post-project streamflows may
be used to initially· assess the project effects on fishery and
wildlife habitat. However, Trihey (1981) notes that average
monthly flows do not reflect the seasonal and annual flow extremes
which may have significant impacts on habitat. High streamflows
may scour eggs from streambed gravers. Low streamflows during
salmon spawning periods may concentrate spawners into confined
areas. Only monthly flows are available below Devil Canyon for
post-pt .. oject conditions.. Consequently, an analysis is required to
assess the value of monthiy streamflow va[ues as indicators of flow
extremes.
. ,, r31/c 3 - 3
The 1-day, 3-day, 7-day and 15-day high and low flow values
were determined for each May through October (open-water period)
for the periods of record at Susitna River at Gold Creek, Chulitna
River near Talkeetna, Tal.keetna River near Talkeetna, and Susitna
River at Susitna Station. The ratios of the values to the
corresponding average monthly flow were then determined in order
to provide an indication of how well monthly streamflow values
represent the extremes in habitat conditions (Trihey, 1981). The
average 1-, 3-, 7-and 15-day ratios and standard deviations for
each stations are presented in Tables 3.16 through 3.19. The
ratios for each of the months of May through October for the
periods of record are presented in Attachment B.
The ratio of annual 1-, 3-, 7-, 14-, 30-, 60-and 90-day low flows
to the annual low monthly flow were also computed for the above
four stations, together with data from the Susitna River near
Cantwell. The ratios are summarized in Table 3.20, and the
station values for the periods of record are presented in
Appendix B. The annual low daily flows. are closely approximated
by monthly flows. The low monthly flows occur in mid-winter,
when the rivers are ice-covered.
Flow statistics indicate that the ratios of 1-, 3-, 7-and 15-day
high and low flows vary both with time and with basin
characteristics. On all rivers analyzed, May showed the most
variability, as it is usually the month when high breakup flows
begin to occur. This large variability in May is also evident on
the flow duration curves. The ratios for May also had the
greatest standard deviation for high flows, indicating significant
changes from year to year. June and July generally exhibited less
variability than the late summer months, primarily because flows
are usually dominated by snow and glacier melt. In the Susitna
Regional Flood Analysis (R&M, 1981), it was demonstrated that
June had the greatest frequency of annual floods (55%). Floods in
June are dominated by rain and snowmelt storms, resulting in high
volume floods with relatively slow changes in daily discharge.
Flow variability increases in the August through October period.
Heavy rainstorms often occur in August, with 28% of the annual
floods occurring in that month. The increase in the ratio of high
daily flow to monthly flow for September and October is partially
due to rainstorm floods and partially due to the decrease in flows
due to cooler weather later in each month as winter approaches.
The monthly ratios for high and low flows may be used as
indicators of the monthly high and low flow values for the
unregulated portions of the river, i.e., that portion of flow on the
Susitna River contributed below Devil Canyon. The 2-dam
reservoir system will have almost complete regulation of flows up to
floods with about a SO-year recurrence interval. Table 3.21
indicates the average monthly spill from Devil Canyon.
r31/c 3 - 4
' .....
~I
...
~I
-
The spills are completely regulated, i.e., reservoir outfets are
controlled so that average monthly flows are nearly constant for
those months. The 'i-day 1 3-day, 7-day, and 15-day hlgh flow
ratios may be used as indices of the increase in flow contributed
below Devil Canyon 1 so that maximum flows expected between Devil
Canyon and the Su.sitn?~·Chulitna-Talkeetna confiuence may be
estimated. Overall, tht: ,;Jaily /monthly flow ratio for the Susitna
River at Gold Creek will be decreased .·significantly under
post-project conditions. Once the Susitna-Chulitna confluence is
reached, there will be also be some decrease in the dairy/monthly
flow ratios due to the str""age effects of the reservoirs, but it will
not be as significant as that above the confJuence.
r31/c -3 "'"· 5
TABLE 3.1
STREAMGAGING STATIONS " -
PERIOD OF RECORD
Susitna River near Denali -US.G.S. Station 15291000
Mean Daily Discharge Records: May 1957 -September, 1966
July 1968 Q Present
MaClaren River near Paxson -U.S.G.S. Station 15291200
Mean Daily Dischar·ge Record: June 1958 -Present
Susitna River near Cantwell -U.S.G.S. 0:-:ation 15291500
~ean Daily Discharge Records: May 1961 -September 1972
May 1980 -Present
Susitna River near Gold Creek -U.S.G.S. Station 15292000
Mean Daily Discharge Records: August 1949 -Present
Chulitna River near Talkeetna -U.S.G.S. Station 15292400
Mean Daily Discharge Record: February 1958 -September 1972
May 1980 -Present
Talkeetna River near Talkeetna-U.S,G-S. Station 15292700
Mean Daily Discharge Record: October 1974 -Present
r31/c 3 - 6
GOLD CREEK UPDATED PRE-PROJECT FLOWS
OCT NOV DEC JAN FEB HAR Ar'R HAY JUN JUL~ AUG SEP YR AVG
6335. 2593 .. 1439. 1027. ,788. 726. 1370, 11510. 19600. 22600. 19880. 8.301. 7972.
38•18. 1300 • . 1100. 960. 820. 740. 1617. 14090. 20790. 22570. 19670. 21240. 9062. •· • 5'571. 2741\. 1900, 1600. 1000. sao. 920. 5419. 32370 • 26390. 20920. 14480. 9516 ..
8:::!02. 3497. 1700. 1_100. 820. 820. 1615. 19270. 27320. 202.00. 20610. 15270. 10035.
5604<1 2100. 1500. 1300. 1000. 780. 1235. 17280. 25250. 20360. 26100. 12920. 9619.
5370. 2760 ..
\
2045. 17!)4. 1400. 1100. 1200. 9319. 29.860. 27560. 25750. 14290. 10204.
•1951. 1900. 1300. 980. 970. Z940a 950. 17660. 33340. 31090. 24530. 18330. 11412.
' 5806. 3050. 2142. 1700. 1500. 1200. 1200. 13750. 30160. 23310 •. 20540. 19800. 10347.
8:::!1:::!. 3954, 3264. 1965. 1307. 1148. 1533. -12900. 25700. 22880. 22540. 7550. 9413.
4811. 2150. 151J~ 1448. 1307. 980. 1250. ' 15990. 23320. 25000, 31180, 16920. 10499~
6558. 2SSO. 2200. 1845. 1452. 119~ 1300. 15780. 155'30. 22980. 23590. 20510. 9649.
/794· 3000. 2694. 2452. 175·1. 1810. 2650. 17360. 29450. •24570. 2!21 00. 1'3370. 10750.
5916. 2700. 2100. 1900. 1500. 1400, 1700. 12590. 43270. :25850. 23550. 15890. !1531.
6723. 2800. 2000. 1600. 1500. 1000. 830. 19030. 26000. 34400. 23670. 12320. 10989.
64.1)9. 2250. 1494. 1048. 966. 713. 745. 4307. 50580. 22950. 16440· 9571. 9793.
6291. 2799. 1211. 960. 860. 900. 1360. 12990. 25720. 27840. 211:::!0. 19350. 10117,
w 7205. 2098, 1631. 1400. 1300, 1300. 1775. 9645. 32950. 19860. 21830. 11750. 9395. I 4163. 1600. 1500. 1500 •. 1400. 1200 •· 1167. 15480. 29510. 26800. 32620~ 16870. 11151. --...!
4900. 2353. 2055. 1981. 1900. 1900. 1910. 16180. :n55o •. 26420. 17170. 8816. 9761.
3822. 1630. 882. 724. 723, '816. 1510c 11050. 15500. 16100. 8879. 5093. 5561,
3124. 1215. 866. 824. 768. 776. 1080. 11380. 18630. 22660. 19980. 9121. 7535.
5288. 3•\07. 2290. 1442o 1036. 950. 1082. 3745. 3 . .2930. 23950. 31910. 144 110. 10206.
58•l7 • 3093. 2510. 2239. 2028. 1823. 1710. 21890. 34430. 22770. 19290. 12400. 10836.
48~6. 2253. 1465. 1200. 1200. 1000. 1027+ 8235. 27800~ 18250. 20290. 9074. 8052.
373;3. 1523. 1034. 874. 777. 724. 992. 16180. 17870. 18800. 16220. 12250. 7581.
3739. 1700. 1603. 1516. 1471. 1400. 1593. L .. ;;so. 323io. 27720. 18090. 16310. 102.34.
7739. 1993, 1081, 974. 950. 900. 1373. 12620. 24380. 18940. 19~00. 6881. 8136.
3874. 2650. 2403. 1829. 1618. 1500. 1680. 12680. 37970. 22870• 19240, 12640. 10080.
i'571. 3525. 2589. 2029. 1668. 16·0S, 1702~ 11950. 19050. 21020. 16390. 8607. 8142.
4~,07. 2535. 1681. 1397. 1286. 1200. 1450~ 13870. 24690. 28880. 20460. 10770:o 9427.
56:59. 2467. 1773. 1454 •. 1236. 1114~ 1368. 13317.~ 27928. 23853. 21479. 13171. "
,,
.
TABLE 3.2 susitna River at Gold Creek
Pre-Proj~ct Monthly F.lows
~
w
I
(X)
.·
SUNSHINI:: STATION Uf'ItATEit PRE-PROJECT FLOWS
OCT NOV DEC
14003, 5639. 3611.
12226. 4712. 3804.
13714· 5702. 3782.
173:94. 7199, '4080.
13227. 5092. 3977.
12188. 6340. 4313 .•
11011. 4367. 3161.
152~2. 7029. 4907.
18399. 9032. 6139.
11578. 5331. 3592.
15131. 6415. 482:3.
16996· o109. 5;;o4.
14579. 66~7. 4820.
13956. 6052. 4690.
1853::),. 5907, 3533.
15•173. 7472. 4536.
18208. S321. 3965.
115:H, 429~. 3856.
10701,,. 5413. 4563.
8!>73. 4048. 2650.
~416. 3978. 2848.
i.2264. 7 •167. 4930.
14313. 6745. 4922.
13588. 6018. 4030.
11284. 4699. 3524·
12302. A93B. 3777.
1~565. 4238. 2734.
10620. seas. 5285.
17399~ 7130. 5313.
11223. 5648. 4308.
13690. 5829, 4199.
JAN FEB MAR APR HAY JUN
2748. 2276. 2033. 23:.11. 22418. 45613.
2930, 2435 .• 2144 .• ·3563. 42196. 58872.
3470. 2511. 22S2. 2357. 11258. 6873B.
2818. 2343. 2317. 4292. 50302. 6.4075.
3667. 2889. 2423~ 3204. 32595. 54805.
3927. 3189. 2577. 2658. 21758. 69686.
2612. 2286. 2>209. 2244. 33157. 73941.
4006, 3471. 2844. 2907. 34140. 19153,
4067. 2996. 2643. 3399. 27759. 60752.
3387. 3059. 2280. 28l'J5. 29460. 6428.6.
4059. 3201. 2675. 2928. 34802. 39311 .,
4739. 3478. 3480. 5109. 32438. 60886.
4222:. 3342. 2975. 3581, 24520. 8/537.
4074. 3621. 2399. 2025. 35245. 56«S29.
2797. 2447. 2013. 2381. 86'15. 111073.
3373. 2962. 2818. 3435, 2:4597.
3404. 3009. 2875. 3598. 16479·
3698. 3294. 2:793. 2639. 32912.
A1B1. 3986. 389S, 4359, 36961.
2218. 2082. 2077. 3458. 21509,
2600. 2448. 2382. 3150. 25687.
3325. 2514. 2351. 2640. 10652.
4257. 3801. 3335 .. 321(), 36180.
3312. 2984. 2646. 2821. 18215.
2882. 25.19. 2220. 2916. 31486.
3546. 2990. 2810. 3160. 29380.
2507· 2355. 2281. 3294. 22675·
4231 ~ 3640. 3171 .• 3537. 27292.
4213t 3227. 3002. 3542. 22707.
3674. 3206. 2963. 3704. 33876.
3498. 2952. 2631. 31?7. 27717.
TABLE 3.3 Susitna River at Sunshine
Pre-Project Monthly Flows
58488.
69569.
66162~
76770.
40404.
47602.
76203.
668~:fo.
59933.
43713·
72836.
56366.
87773.
48044.
59849.
64198.
JUL AUG SEF' YR AVG
59179. 54849. 27734. 20201.
69474; ~8356. 51069. 25982.
64937. 53363. 32057. 22014p
54231. 49954. 33737. 211395.
53386. 57701. 28376. 21779.
70894. 77692, 35385. 2G884.
80569. 69034 lt 44495. 27424·
62302, 53243. 481~1. .:!6448.
59850. 56902. 20098. 22670.
67521. 71948. 36915. 25188.
5822:4. 55315. 43086. 22478 ..
6~640. 606!6. 36071. 24922.
67756. 61181. 38711. 2665'7.
78219. 52938. 29182. 24086.
58836. 46374. 23267. 23819.
650•'2. 56375. 53703 .. 24856.
55243. 62007. 30156. 22820.
77125. 82747. 37379. 2/371.
69735. 46730. 20885. 24016.
45267., 24656. 14268. 14219.
60771. 54926. 27191. 20250.
64787. 74519. 32402 •. 24505.
62292. 51254. 34156. 24277.
51711. 51085. 25238. 20132.
51::!67. 43222. 29114. 19071.
75692. 51678. 35567. 24890.
55506. 52155. 18502. 1.9865.
62194. 55157. 32719. 25126.
5793.0. 42118. ::!2742. 19781.
71774· 48897. 26790 • 2.2993.
•
63178. 55900. 32304.
SUSITNA STATION
OCT NOV
26869. 11367 t
18026. 6933.
31053. 16364.
•1·1952. 16289t
2Ql69. 11829.
23896. 9168.
19923. 10522.
41822. 215•18.
52636. 19887.
305•13. 9528.
25754. 10165.
3379~. 12'914.
I 290~9. 13043.
II 27i~16. 10755.
f 37846. 11702 ..
~ 287.'l7 t 10·,S8 •
36553. 12313.
26396 .. 12963,
37725. 15873.
tn94o. 6606.
22683. 6799.
32817. 16607.
32763. 14922.
26782. 14853.
20976. 10113.
19520. 1v4oo.
31550. 9933.
30140. 18270.
38230. 12630.
36810. 15000.
30055. 12659.
UPDATED PRE PROJECT FLOWS·
DEC
6197.
5981.
6989 •.
9746.
5272.
6183.
7295.
14146.
10635.
4763.
7005.
13768.
8977.
8865.
5626.
6127.
9159.
8322 .•
15081.
42/9.
5016.
8633.
8791.
8147.
6081.
9419·
6000.
13100.
7529.
9306.
8215.
JAN FE!t MAR APR MAY JUN JUL
6072. 5256. 5377. 5657. 66294. 101616, 124890.
7074. 7295. 6382. 7354. 59273. 92255. 123164.
8274· 7036. 585~. 5985. 45294. 132547 .. 137322.
8069. 6775. 6350. 7993. 88840. 130561, 125949,
7202. 4993. 4980. 6306. 58516. 108881. 116732.
7255. 5945. 5316. 6412. 58164. 169045. 148877.
6179. 6831. 63,24. 7182. 82486. 161346. 168815.
10600; 8356. 7353. 7705. 63204. 176219. 140318.
7553. 6387. 6679. 8099. 70321. 112897. 122280,
7795. 6564. 5666. 6469. 56601. 110602. 146217~
6716. 6310. 5651. 58'30. 50062. 84134. 129403.
12669. 10034. 9193. 9803. 85457. 151715. 138969.
9050. 6183. 5951, 6635. 54554. 163049, 143441.
8671. 7854. 6058. 5565. 53903. 85648. 14642().
6351. 5762. 4910. 5531. 35536. 153126. 124806.
6952. 6196. 6170. 7120. 49485. 110075. 138407.
8031. 7489, 7091. 8048. 52311. 125183 .• 117607.
8029. 7726. 668.3. 72!31. 58107 •.. 134881. 136306.
11604. 1153.:,!. 8772. 8763. 941,l3o 137867. 130514.
5033. 5137. 5172. 6452. 44317. !:13226. 102121.
6074. 5581. 5734. 5769. 53046. 94612. 132985.
6509. 6254. 5883. 5788. 29809. 12225S. 139183.
9390. 8458. 6646. 6895. 74062. ;176024. 142787~
7609. 7477. 63t3. 7688. 64534. 122797. 123362.
7402. 6747. 6294~ 6963. 61458. 67838. 102184.
8597. 7804. 7048. 6867. 47540. 128800. 135700;
6529. 5614. 5368. 7253. 70460. 107000. 115200.
10100~ 8911. 6774. 6233. 56180. 165900. 143900.
6974. 6771. 659-0. 7Q33. 48670. 90930. ·117600.
8823. 7946. 7032. 8683. 81.260. 1199()0. 142500.
7906. 70~7. 6320. 6979. 60463. 123698. 131932.
TABLE 3 .. 4 Susitna River at Susitna Station
Pre-Project Monthly Flows
~UG SEF• YR f.1VG
106432. 39331. 42113.
100947. 73471. 41513.
116186, 82076. 49582.
97610. 44168. 48942.
128587. 66:~75. 44978.
120120. 53504. 51149.
131620. 10~t~18. 59395.
124813,. 87825. 586:::i9.
99609. 53053. 47503.
138334. 67904. 492 119.
113972. 81565. 43881. '
116697. 62504. 54792.
121221. 74806. 5299fi.
106707. 70782. 44912.
92280. 46110. 44132.
111846. 89944. 47627.
118729. 63887. 47200.
13;'319. 89527. 5'2795.
86875. 42385. S~\094 •
62368. 34085. 31228.
tl772a. 80585. 4•l:717.
133310. 69021. 48006.
107597. 60220. 54045.
107261. 45227. 451;71.
80252. 56124· 3603'6.
91360. 77740. 45900.
996~0. 48910. 42789.
125500. 83810. 5573\).
102100. 55500. 41713.
128200. 74340. 53317.
110841. 65963".
60! Jl
' OCT
7731,.
691.7,
74/\4,
10094.
7·196.
700f ..
6A4J,
769A,
t0\04.
697~.
I 0 451 .•
96UA. It 7100.
1 8616.
BJ.Ql.
w 70A2,
I 9097.
1-' 6876. 0 7!'iR9.
6793.
717::!.
7lH.
690(),
66;l0.
701>0.
.!1916.
96Jl.
7JH,
92:U •
71 .. 1.
778R,
CREE"K f'OS.T-F'ROJEtT FI.OIJS tr.ASE A) DF.r.,2jtUR1
NOV [1EC
9073. 1;!669.
7 fl?:'). 9.,1-t.
10635· 13130,
11100. t ~~9:10.
9991. t2729.
10074. 13;'74.
9791. 1;!529·
10i1l~ 13371.
119 .. ~. 14487.
7AR6, l0~!:!9o
1('1741. 1:1430.
lOR91, 1:\ 'i ~-'.
10591. 1:13:'9.
1069lo 1;12;!9.
1()141. 12723.
9011:!. 1:1440.
Y9fl9o l'2Hnt.
7599. 1173:'1.
tO'.H, 13?04.
7664. 93~4.
8004. 9:119•
7780. R.9S7t
775fJ. 11A79 •
9997• 1:!694.
79~2. 9300.
771~ • 930-1•
9AR4a t2310t
B175i 97t7•
11411>. 13019.
79Sia 9:1-\S'•
9452. u '130;
JAN FE!' ttAR APR HAY ,JUH JUL AliO
IOR\4, 8 1~1,1& 7877. 1931. l0434t • 0176. a:na, :"i17J •
8340.; . 6~14. 6604· 6355. 100H• 9:t6:h i'n:So. 6111'
1l:iA6o 917:\. ao:u. 7A:i.-\o • IH13A, iJ7~2. ~2t1. tw:a.·
10RB&, fl9'11:!. 7971. R191io 1 1!109 i 1 :!91 !h 7cH2.t 94:\~t.
11087. 9173. .7932. BOJt, l:H61a 12966o aono. 96~U.
1150 I, 9~7:\. 6251. ·79'i'Ro 10179. i:?J09e Rfl:iRo 14554.
10766. 914,\ I R091.t i.f972. 1 :!~tl7' . lJ~!Hia 15641• J6005.
11497. 967J~ ff:J:i:.!o 1~'93 •• Ut:Sl, • !1909. 9472• 1024J.
11759. '/4£10. 8299· flll•h io:ua; 10704. 7S?9'2t Y!W7.
112J4o 94RO, tu.u. IH O:i • l~f 4 ~11. 12M:'S • 9-1tH, HM2,
11A3:!, 96~!h •u4a. 11A7 .. lOJH't Y2:W• UJ!'19e t\411.
tn.IY• 99~11. h9111. v~;u• h~!91'. l:l741. l0711lo 1'20:l1o
11607. 9A1l• t1~52o 9281·. flRJ!Z. l.SJ:SJ. s .. 6:/:lt. 1 AH' •
UJf17, 4jA7:1, Rl52a 179:1. iJ!HOi 1240n. l!i77:So AUlJ•
10fJJ5. 9139, 7BH• 7R1R. . . R:l7J' . I Mi:?4 • •47R7t 9402.
107~7. 90;1J, 0051; 7Hli 9600• 1160~. YYOila SbHA8c
lltll6. 947~i. tH:'i'lt UJS6, HlU'/, 1 H:S .. • AJ70e '141?,.
JJ::'nt.. 9573.· RJS.\ • · 80:>6. Jo~o4. :1 iiHMo 12937, 1 71<\0•
117~9. iOO'l:Ji 90!H, RJ19ti l09?.9t i2Y'.!1t t~•tHH), u:t~!'~·
f0510a RR96t 7967• R091. 9JI2t ff:"i 47 I 60~13. ~·6~Q
R4:!0, 6fJOt. 6968' 5R7:St 6737· !t:ss~. 9506t ~034.
R'l'l'J, 7128. 7462. B40Jo R91At 1283,., aoa6. 6132.
1~0 • .,6. li)~HH 1 R9H• R2Ylt tJ4n. 1405Vt 14:iQll' iOA~ih
109fl6t 937:?. Al!H t 7A51a ll:l26• U 0/.IA * MiA7t ti:)fH •
7aH: 979Al 7876. 7R!t9• . 10869. i00-\6t • 1':ii.O i 56B:la
ff227• 6St!i. 7!573. Al7Ja U:zs.t. i2710t i469(h CJt;t4,
i0760t 9U:tt aosta BO:"iOi Ji ']58 t 11-496•' 61i:l41 !'1;!71•
8191. ouo. AMi t I A260a 11696 I i:tn•n 11911· 9AJ4.
UR15. 9R41t t17!16. f1'll1:1. t129:Ji fJHA!h ' 75U. ':i'/1'1•
Bi26, h9At fJJ:Slt UOlOt 9076i 9B7Cc llO~la • U1t •
10!'7 ... 8943. • 8137. 7990t loda. hCJ6i. 101.<~0. Y;i:S:f •
TABLE 3.5 Susitna River at Gold Creek
Post-Project Monthly Flows (Case A)
SF.P YR t'tVR
-'1906. 072ot.
~~~'"· Rl51o
l>6Y;!, 9516.
8148. H>OJ:t,
610Y. 1609.
R1:iY, JCll:S!'i.
HU?. UH2i
12709. 10347.
499:J. 9796.
Y909o 10106.
l1!?5lt. 9~49·
64116; 10159.
12t77. i l:'i72.
tu:u. l099(),
Sl:'i6, lOCI~().
123:19• 9A99t
5J!):S. V:'il!B.
J<\90:'1. 107\2,
5032. iot~A.
<\9:171 7772.
:i!:i1. ,,.,.:;.
!i:?70. 80Aia
!litH• lO.lll3o
-\YJ:.'. JSJO,
li413t HUI'Io
~299, 9297.
:'iCI70i 8962·
5061. 9:113.
5071• 9057.
:S02"• A~9R•
nu.
sumnUHE STAo
OCT NOIJ
15404. 12129.
15-145• l1 '2tl7.
15606; iJ:i9J.
19~fi(l, l:i090t
l5lt9. 129BJ,
138:?4. l3Mi4,
12903. 1:!25A.
17144. H920.
20291. lt.923.
13719. JOOA7,
170:?1. HJO.!-.
18Rlh1, . t~ooo.
w 1631.3. 14:5""·
I 15A 49, 139.43,
}-J ::!OH7o SJ79Ao 1-' 16:-64. l37J:l.
20100. 1:121?,.
·142641 10294t
1339:). 1330"1.
l1!iA4, 1 oon =•.
13H4o 10767.
t~t~o. 11840,
15J~b. ll41fh
1539~. 13,7:121
144\lt. 11098.
l5479o 11013.
l7457t 121~9.
13940o 11-413.
19059 I 150Z1•
134571 110641
l:SBJV1 12914.
F'OST f'RO,Jf:r;T fi.OU!l lCASF. A) llf:'C •'2J d 9Ai
OEC
HR-4U
(~ltll.
l:SOl~.
15~UI).
15206.
15542.
1439\i.
161Jl-.
17::162.
12:1oa.
J6053o
1/II:JJ •
16049.
1.:5919.
H76:!•
i:S76:S.
t!'i19!i.
t 4091.
157921.
11072 .•
11501.
ll627t
14291.
l52S9t
11790·
114 78 I
l39.U a
12:S99o
1 t\ !i .. :\I
11976.
'14331it
,JAN FEl' HAR APR lit\V .mH .IIIL AIH1
!25J!S. 10449. 91A-4. 9J77t 2i3~2' J611J9. 4.f917t 40742,
10J10. U21.9s aooa. ll:tot. ~IH2?. • 47H4o ~1554. ""191.
U:Z!'I6. 1 OAR ... 94JJ. 9:19J. HA77, ~Ol10a 411:1Ro 4() .. 70;
12AO~, 105l!h \146!1. 1QA7'2i ~'2041. ~9670. 4lloi'J• ltl7V7.
1:1454. 11062· 9~75. toooo. ~R 476 '· -\2421. .UoRAo 41!129·
137141 1136;'. 972A. 94:'16. 22/.19. :s l9J!h 5~ U:l. 66496.
17;199. 104:$9. 9:1A1t 9266. 7.77fl4t ~3A56• 65120· • 6MH19,
1379:1. 11644. .999()1 97(11), :tt:;H, A09A:Zt -4746~. 4:!946•
lJilAl. lHc\9• 97941 99A0o 2:S377. 4:i7~6. H9M!e 4~iA19,
1:t1JJI t r~;n. Y431o '174\l. 1.AR9fJo t$3061· til Y2:\'l :i:i.T1t) •
13846. 11J7·h 91J2/.o 9:l9!h :?'1:1J4. l:t040o 4:1110:\o iHUJA,
14:1?.1.. l1 ~!iO • lOII:tl I 116'10. 4!AJ7:i. -tran. o1V7fHh ~I)!H7o
140091 11 :a:s. 101271 JOlfllo 207A2a 60MH.,, 5A:i29. 54(19:1.
1JB6lo 11794. 9:l:H• f19RB. :n:\41~· .,.Jo:w~ ~9:S94. ";'9Bt.
12~84. 10A20e 91tH· 9Sl41 1:271 H 11'011; :i06?l• JR416o
I JlAOo 111J5t 9969. 10016. 2l.207t H.no. · 411l0t -i611Jt
1J1901 1J ·~ 81, I 100?.71 10179. 16961. 50/:ilo -'\,1153. -11~891
13484. 1141\7. 99-H. 9:'i2Ro :.•79:J&. 4~\'iJR, &326~. 6?367.
139ARI 12159. Uo49. 10140. 31710i I'\BH7t • 57ll:'ia :17989.
1200.4. 10155. 92:!a. lOQJ9, 1'1771, JJ4:H 1 • J:S:!~o. '.~U9.U •
10196. B4fJle f:l574 I 7li'-45. 21044. 4052-1. Jl76t7. -109AOo
10105. 8606. RR6J. 9961. l~A2!St · :56112. I\B92J• u;;.ul
14044. 119'14· 1 O.•HI6 a ?7Y1. :!71R2• H411:il 540:-llh 4~592·
130911. 1 H:She 9797. "96-\5, 1R506o o\J\99 .. : o\004A t Jt\l76e
9R!i1.i lO:S4o, Y:l71..o 978:4. ?.cH75• .151HJY 1. 400?.7· 326fl4t
102571 ROJ~, A903t 97-10i 2521Ht :SJ2Jit. 6'1M2o. 427l:t.
12293. 1052R• 9432. 997t. 2i!lt3t ~J~A2t -\J:!001 J7A21\t
1059J., 10182. 1 03l2 .• 10111• 2A:a9Ai c\J:S:l2. ~1141• ;}:)7!'i1~
JJ9V9o u 400. l015J. H) i ?.3 • l90:S2· :11R:i'l, 444211• JtM:s.
10403• 99lfh iou .. , 1028 ... · 29U9:?i .oi4029• :S~98l'St 39M ft. .
1:!619. 10659.' ~~53• ,9000('> ·24lJ.tB• o\H3Ua 49:-t~fh "'4l974'
TABLE 3.6 Susitna River at Sunshine
Post-Project Monthly Flows (Case A)
SEP YR AVO
74339, ~09:'14.
4Z:fU • 2:'1072,
:l-1269 •. ~201~.
,6AlSo ;!~39~.
2~!'ih:\t :?1R4R~
:192:'1 ... 2~Rt:'St
407fl:lt 274?.-4.
.\1110. :<!&440·
17~43. ~Jo:o;J.
29904• 2-ltHH;
a:m:t~. :.024YOo
~91A7o . ~4932·
~t499R• :Z664Bo
:1499:1· 240Rho
HHI!"i2t . 240-47.
-1 l-.4\ V2, 246~9.
~J7A l• 1.299~.,
3:'iH-1t 27132.
111011 ·:!4Jffla
HlJ:!1 161\RO.
23~21. 20J60o
~3232. ;!2Jff0o
2739(). :!3110Jo
!tlOY6t '0610.
2?.'277t 19!H>R.
~n:s~:s. 2JV:S31
161\911 :!0690.
23940i ~4:1191
i9ZOA• 20696.
~10411. 2211..;.
:.1MIH•
SIISITHA STATION PORT PRO.IF.CT flOiriB CCASE' A) llf::r.. 2;1, 1981
OCT NOV m:c .IAN FEB HAR AFR HAY .IIIH .I Ill (IIIG Sr.F' YR AVO
28270. 17fl:S7. 17427. 1:5059, 'tJ4:l9t 12:'i2FJ. 1:•7lHo · 6:-»:•ta. 92H1;.t, 1106~8. Y2:i:'!i, :\~9:\c\. .,:1RA!"i,
:!114!5. IJSOfl, 1429:5. 144!'$4,. 1JOR9• ll2.,6o &7097. !'i:'il99o 709~'7. JOA~-t-t~ 073f1Ae A47-19, 40AO:l• .
32946. 242~!1. 18219. JBOc'lo, ,15209~ 1J004. 1:19:.•1. -11i7ll. u:w~s-. 1:001-l:ia J O.i:?9 .1 • 742£10. .,9~1-);?.
~&844. 24ll!O, 20916. 17\15~. 14941. lJ~iOl, J.1:'i1:1. t1 Lll'/, U6Hi6, I Lf.lY i , I!~ 'l!i:J • J/04A, 4fl'14?.
22061, 19720, H.!Hllo 169R9, t :u 66. l;l13:?, tJto:t. :iU97. 9~497. l04•U2. n:? u~;. SY'I.-\4, 4!'i011h
25:iJ2. ~h4R2e · 17-U 2. 1704.2, 1~010. 12H7, t:S2l0• :;9o:.•<t. • !H.:?S'-4 • t:t0\75. 1·01192-t. ·tJ:n:' • :'it079.
21Bt!ia 1RHJ, 18~~ ... S!'i96:io 1:5004, 13-476. 1-420-4. '7711J. 14121.1, 1 !'S :u J\1\. 1 :uov!"i. 1\l():";O:'S, ~9:Jl':S.
43714. 29139. 2:SJ7~ .. :?0:107. l.-\5~9. H:'i05, 14-H'fh ltOI\0~. 15A04Ro J;!54tJQ,. !H!Hc'lt RUilt4, !5A~:i9o
~4!'i2R. :nnu. 2lU:-illo 17;147. 14:'il'l0t lJOJI), 1 41\fJOo 679:tv. 'i lYt)l , J 07:1'1.~. ll6J'U,. :SIH9R. ~7fiR~'>•
3:!70~. 1~01\4, 13479._ t7.:uu. . 147,\7. l~tl17. ll:I~\ •. !'S1039, 99:177. t:Hl61R. t.:nn,.,. /.OOV;I, 4ROM,.
%7647. lf!O:'ilto lll:1:15. 16!'iO.lo 14411Jt lf1AO~. 12497. Hl}Y4, 7186~S, II 47tl:O!o 'ilt 19 .h n:ttJ. 4 .HHJ J •
J:5~74. 20BO~. 24997. 224~6. 10:?06. 16JH, ilt.llf ... 79l9.,. tJ6(Hl6t 1:?~t11. t<~Af•~'H• !\!'. ~(l(h ~<4HC1 t •
JOB13, 20934. 20206, 1flfi:S7. 143:\6, 13103. 1:1:'16. :'i079h. s:tt-ta:.t, 13:!.'H4· lHt:lJ. '7IU9J, ~:>r,·nh.
29609, 1A6H, 20094. JA45A. 16027. n:uo. 1 :l!"i:Hf • 46lt13. 7!!0:$<\, 1 :?779~h 977flt). A6:l9J, · 4-491:.!.
397ja, 19593. 1685!5. 161JR, 1J9:J5t 12061. 12<\H. ;tvAo2. Ui07Uo 1 L•6~J, 9432:!~ •tl 119:'.. HJAO•
w :!9539\ 16721. 17:156. i67J9, 1<4:tl.9. tJ:t:u~ i:J70l. 16011~. ~:59!')7, tj,t()U5. 101594. U:.:'9JJ, -17400.
l 3R44!'i. 20204; 20~119. 17tJ17. 1:16(1;:?, 142-tl. 14629. 5~7~:4. 106.16/o \Dl\111. 10•1.t11. ~$7497.~ 47:173.
}-1 29109. 1a962. lB:iS7, 178 1~ •. J5Ei99, 1JRJ41 14170. 5:l!;lt. 117:157. ~~·:2·1-13. l2!9.lllo H756~, :'1;!5:'16.
(\.) 4{)41o\. 23764. 26;11 0 I 2l:l9i I 1970:5. Hi92J, I!)JH I RllAY:l. 1!.9~4-\. 1~7H~4. 1fJO.H, :U!c\01. ~.04h0.
1 9'i11o 12640. 12701, 141119. UJUh l:?J2J 0 130:13. -1:1579. 76:?7:1. ·9:?074. :'illh:SJ. :t~919. ~34.\9.
261'31. J350Ao 1:3669, 1:1670. 11614, 1!924. 10:)64. 4AJ9;$, A?5.t4. U9BJJ, lOMR2, 7Md~. 4482/,,
341,73. :?o9ao. 1~330; 1J:?fJ9, 123~6. 12J9!lo IJ1Cl9o 349A2, to:a6~. 1 n;u v •. t oro :1:1. :i'tA5lo i!lRHlt
33R16o 195tJ7. ltU 60 • l9U7, li .. Bl I 1:t197, U~i'O. A:i664 I 1 :mAsJ, ,lJ1~2S~ 9Hl':l5 ,· :;,454. :'ll~•72o
:!B~fl6, 2:!!597. 19J7A .• 1739:'i. 156<49. !J46-4 I ·14:'i12. 640!.1:'1, i 0606:i. 111M'9• \'~·~,!l:?. •\\OIJ:·,. 4~~~~49.
24:\03. lt.:'ll.2, 14347. 14372. 1476fl. 13446. lJAJO, 5t.t47, 40()1., .. C/t)9•H, A'l/14. "19'.!1'17. :1617 4.
::!2697. l647:S. 17120. 15308. 12R4fJ, tJnt i 1JH7. 43444. 109:.'00. J 2~.'670. fl~:i94. i'Onn, 114 9/.J.
33442. 17A24t 17229 I 16:11~. 1J707t' s2:uy. 1 :sv;w. 6909R. 94116. lO~h94, nstn. 47()99, 4Jh\:io
33460. ~379:5, 20414. 164~2. Z'i4:iJ. IJ92:'ie l~RtJ, :'i:'ilflfl, 1416:\9. lJ:?R47. 1160'f4 .-77()31, !'i19~a.
J9R90, ::!0521. 187~9. H760t 149H, l:i741o 1:16\1 .• 4:'i0l:i.· ft074~i. 104tHM .• 91187. !il9t.4. 4'26:!R.
l90He• 20416. l6974t 15552. 136:>9. HlR;t, 1~263. 7io466, l(t4()RO. 176711. UUYU. 6H:i'f<1, ~~-4RAt ..
3:?203, 19643. IBJ7S, 11027~ !414:it lJl4J. 13~~~. 57S6~. 1078l.a. 1 U12YY, YfJVJ!io 60!)0~ • .
..
TABLE 3.7 Susitna River at susitna Station
Post-Project Monthly Flows (Case A)
w
I ..... w
~
GOlD CREEK POST-PROJECT nous lt:Asl:: bJ DEC.2lrl9R1
OCT HllV DEC ,
7B:SJ, 7870. 90!'Slt
.sos:s. • na:s, 770lt
"5827. 1>522. 7309,
0:!02. 6097. 91!'11.
7630. 7876. 9120.
5701. !.975. 9:-!93.
7094. 7669. 906?.
78'13. 6149. 9210.
B1z:t. 0377. '1121,
7:.snn. 707h. 92H,
7cSJ7. HOOJ •• 9292.
7990. 9031~ 9458,
7524. 700B, 91!l'.
740A, 7654. 903V,
1501. 7929. 9077,
7]71. 7801. 8916t
92291 1899, 9209.
3664. 6299. 8123.
7126. 77.96. 9146.
6932, 77H. 8969,
:So\94. 6963. 9:539.
61!55, 66fHI. 7565,
6087. 6783. 7629.
6347· 7.219. ,82!2t
634<\1 70B0t ao;u.
:5934, 6521t 7390.
6324. 6!536. 7327.
6394. 7252. BHJ:
6291. 6781, 7:S49t
5874. 6~12. 7274t
6901. 7360. 859:1,
.
JAN fEB HAR AfR HAY JUN JUL AtiO
aoato. • 6789, d907t :m~ 1, ROlla 7497. 12967 • lfJfU9o
66100. 5:tftoi ~221. :S71:io no:z • 675lu 1~744 •. 10900,
• 7~0:5 I la7A7a 6fl76o :'i729o 6J4Ro 11 02lt. IJ~'.7tlo JY03Jo
RlQ6, 6009, ,\fi~-4, ~R:!l)e 9J~~i j()l93. 1214\6,. tvnot.
BlOJ, 6BS1t ·.690?. !5929. l07:i" • 1017Ye l;.t9::\..6e lY'llltlo
~2,f:H• 69Atle • 69:'iJ.· :ifl17. 7751. 9J98o t:to in • ~.,614.
BOA~t 6fJAOo 7017. ' :saao. 9884, 10:516. 2lf32t • 2.t!l:so.
IH91• 69J:i. 6l'BBt :sa :sa. B71Cit \127:2. 129:S0t ·20~4:\s
021l4. .6RJ:i • 6fi-10t 51H9, B()Jlt 7941• l:?tll\7 •. 2::.!2:11.
8~70. 7022 •. 7!)~4. c\OOH, 11024. 9o\10, J:tJ60. ~·l;·~~-
B290i A922t 6942. 5A17e 7F1:tll. Mi:l~ • 1:099lt Hr'2fi4$
04fH't 1(:11.6'. 11~a. 112:u; At106l io9a,n 1937~. :nn c)l).
0142~ ~R54,· 4.929. :5826. ~ ;175. i'\5()7• 25A~o, ?:f5:'10o
81'2'2. .,_,j..,. AA!!; 56.,;,, HA-4&e Ylt'IJ • 4!:1/tl~. ~.,b71t tiYJ..r;e·
806::.. 61122. 6890~ :S762. :.an:s; htP:'it 214VJ, UHOa
796!\. 6724. 68:1lt :S745t 717:1. 8099. ·t:tn4 ~ 20fJ2:l;
8210 •• 69!ile 705lt i\04?• 11\YH il4lYe 1 :t07 ... lY.H:Ia
8J20t 7ou. 7093. :'5972. R1 Ofh 921-\a 11\JH, J:/620.
R:!J6, 69661 70:'i:li 59U, QH6i 102041& 20"226t 17171 ..
fHlJS't AaH. 6937• !592 ... . ~939t 590~• 12199. BR19,
BA:H, 7JHo 7:'i2-4t 6304. . u,JA, 8979• iJ26B, 191Hl7 •
916J. 7793. 7990. 6A24e .?on. 105:'1Ht 127!'illt 19:t!H,
6:'i06. 70:i0t 775;1, II:SJ~. 11H4t t·174Ye 14HlOJ, 1R.lY/u
7()45· !571!. ,5:'i~7· 4460, 5299, 61.17. 1~4:;1 Ht !H:orn,
6879: 5:'i67J :SH1e 4J7Bt A9:lni '.-·1~~2~. !2740a 16~20.
6914• 1445 •. 111~4. 6H~. 9~!6H J'l'):ifiO I 13282. 111090.
6460. 7004a 7120. 6079, 89611 A909, 12437. 18~62.
6BRl•. 5560i !S402. 49H~t· 91 (.ifi lUcWl 1:!819, l fi62.Y •
. 6-URl 62.an;. )0201 5R<Hh :S8to • A112o 12691, 16:t9(l.
?JBU ~RB1t 6646. 5754t c\{l:i~. 411J, 1A9H, :104&0 ••
717'1· b&~. AA:s1; :iBJOt tl01t. '1~:S:s. i~99Ai 19'124.
TABLE 3.8 Susitna River at Gold. Creek
Post-Project Monthly Flows (Case D)
. Sf. I' YR AVO
.SJOlo fl'19 R,
U:'i:H, 9507.
1 :L:'HI2 o 9044.
l~:!70o t Ul)::\!'$,
124:lJ. 9 fl'll•.
,.,';!90, Y'l-47,
IIIJJO, 11H2e
1 VIHIOt 1(13471
7:S:SO, VHJ,
J/1920. 11H69.
14197. 9649.
u:.1o. 107:SO,
l~R\'0, u~:u.
U.l?.O. 10'190.
Y~71a V793o
u:nw. J(IJ17.
11 :l!'iO I 9740 •.
UR70 I 1MJ07 •.
• HAle\. 91"1·
5CI9:t. 7!'i.J It
91:U I 9JSO.
U894. '1-tao.
115:!:1. 95:!41
9tli'4. 8049.
11970• fl7.61t
~~~2451 9287.
6flRl., R~26,
11914. 9'039.
l\6(17 •• 798:5.
1 ()77() •• 89!'58.
t2J71·
SUHSHINf STAo
ocr NOV.
15~4'1. !09?6.
14 4:13. 10!'#'7.
1391\9, 94f!O,
17l94. 11199.
15~53. 100l>R,
~~~';,. lO!'i!'i!io
l31:i4t 10155,
17;!09. 1~!1:!8o
ta~to. 134!5:5.
J 41 !'i5. I!O:i7.
u~to. fJ 569.
t 7192. 11140.
I! l6\R7o 11765.
J 41.41. 20906.
I a u.n. 11485,
JcS959t J 2474. w l 9~3:!o 111:!2. f
1-J 130~:!. A994o
ll:::. 1~932o lQD56o
ll70J. 10162.
11706. 9726.
13JJJ. 1074Ro
14S!'i3r J 0435 .•
!5109, 10984.
1309~. J02:'i6,
14J9'7. 97:19.
14150. B7BJ,
J.3140o 10490,
16109. lOJAlio
12190. 9625.
149~~. 107·4.1·
·.·
POST F'RO ,Jf.C T Fl OIJS <CASF. bJ [I£ r.. !Z;ft us J .
J:IEC
1f 2~!5.
J0-407,
9191.
t 15.11.
11597.
115&1.
~09:10,
1191lJ.
1260:7.
!1;!93.
ll'?IS,
12:!cSRo
una~.
U729t u J 16·.
j 2241.
1154:1.
l0479a
11654.
I 0737i
115~1•
l020:So
J 1)041 ~
10777.
J 052:t.
9564.
99ROo
11025.
10:!7:s.
990Jt
11022.
.IAN FEF HAR Af'R HAY .IIIN "'Jlil ., AIJG
9A07, 8:!77. B2Ho 7262'. 18924. 'JJ:Ho. 49!')46. !537f)B.
aseo, 6975. 6625. 71uH• J5ROI1o 44RJff, 5964fl. 57596.
9075. R29R, 8278. 7U6, 1:Z1R7, -4i'J96t 5fR:?5, :i1·'11~.
• 90.!4. 83.12' RJ"it. 9497. -403117. "691Uo 46797, 4Y1-t:'i.
10-470. A740. R :'i-4 !"i • 7R9R, U066, 39734• 4:'198:?. :if:\69&
j 0117. 8717. U4:JQ, 7335. ?.0190. -19224. s~t-t:u. 7nAHtt
9694. 0196. G2A6, 7174. 25381. :sun. 71411. 6903-tt
10497. R 9tM, 9f1J~.· 756:1. ;!YltHh ~ll~'Mio :Sl 94'l• U~94Aa
IOJAdo 95241 FIJJ:Sa 7 61l!'i. 22A90e "'~99a 499:17. :S661d.
ji):,?U?o 117,... 8:1:"1~. 76!'1:1' :!44\14, ~W:Jl~. :i:'illfl.t • ' c\301~~.
J0504o 9671. a-t:w. 7445. :.u~nt'fo, J(l~40o -482J5, :S!009t
1071-\o 8750, RO lfJ, fi69~. 2:lrlfi4o 4:l.U9o :sa .... :.. cSo6H.
10~64a RM6e R:iOA,; 7707. 1UJO:$a ~ff7 J4 •. . 677~)6, U tAl~
1059~. 90J:Ja a:.' to. 60d.'ilo 2~o6lo 403()6, A9i01t :S~'i':l9.
98t4. RJ03• BiRO. n9a. lO::'~J1 n&7R• 57:179. 46374.
J 0371h AR:?6o fJ7:Sl. 7020, iEJ7BOo ~J6&1t 50:'i96o :S60fl0t
J O~H 4 • Afolll)a H6:!/.o 7970. l45lfh 4IIO;J(Io 4fi4:)1. :f~52~.
105lfio 8943• a~n~~. 7444. 2:$540. .451M6t ·6467 J. 0:.>7-17'
JO~J~. 90S~, 90!i:1. BJ70, 2.9257. !S~..f22· AJ:; 41 • <467:11.
953J. fU73, AJ9R, 7872• 1739Ar J0809o -itJ66. 2465A.
1()410. 902~. 9130t riJH • :?1R-45, J7951t 51379• :S40J3t
11041 .. 9271 i 9J91l RJR2t 1Jn6. :iJAJA• SJ!l95, 6196lt
95cHo flR~.l, 9:!/i:i. IH>J5 • ;!5764t 4-1175· :i:!~i~!!i. !'iO.ll!O,
9157, 749!5& . 719Jo 6254. 15279• JH9101 4:'oAR9, ..9367.
0997, 7 ,,09. 6937. 6J02. 221.42. .:13.16'/i 4!i:lU • 4:1·.~2~.
B9Ht' 9964. 90141 0039. 2.:129l ~ 50906. 61254. 5167Ao
799J. 8409i A501, uooo. 19222· .. (IA9'51 4900J. e.ocU 7 •
9::'85. 75A2a 7073. 411\1! :?4n•o• 60972. :S2~0Jr :\4!'146t
fJ&:!2. i'B-47. fl417. 7MJa, t.S567' 35106. -49601. 4t!UR •
965Bl 9801. BA'i• nooa. 26661. .-J.JJ2t. 39BORo <4RR97o
98:!4. Mut. AJltllo 7MU. :·:!2·bl. ~5110:1. MJi!1. iHJ-15o
TABLE 3.9 Susitna River at Sunshine
Post-Project Monthly Flows; (Case D)
•
SF.P YR AVO
27734. 2J22R,
-42Jt.o. 2!H21,
JOl!'i9e 21542.
,lJ7J7' ~4.19~.
:nnu1. 2:'036.
:I~JR:5. ?.:lf>:!1.
H49:So 2)'4~4.
~IH21t ?.i.HR,
:;0099 • 2:Z.670o
:fll'n!'i. <!:H RR.
:run:r, :!~ 4 S' fl.
:16071,' :-•9:?2.
:tMH • :!66:17.
29 J R2:• '4 ()fl.~.
:.!:J4'67o 2JRt9,
:iJ70:t. 24R56o
!lO Hi& • :!:11 A 4,
37379. 270'11.
:?Oflfl!i • 240l6.
J42Afl. 16?.40.
27191• 2Hlc\4,
29£l:S6t 2377~.
J:ti!79. 229115.
2~;-:Hf • 21H29,
~!110l4. J97!'i().
31:SO::?o :;•J9<1l.
JB:SO:;t, ;!():1!'i4 •.
J1S9Jt 240A5.
?.U-42, !9/):!Jo
267S'Oo :?2524.
:st::S041
SUIHWA
Ur.T
~fl:lR7.
201JJ.
ll;-109.
4·19~:'.
2~1S'~.
2'\:\07·
2::!0.-\Ao
4~Hl:\9,
s:m-t7.
JJt~o.
26R:l:l.
33970.
:S06:S7t
:!94()1,
39904.
w 30~~\.1.
I 37577' J--1
U1 :!7097.
3?9:St.
UO:itl •
:!50!'i3o
JJAA4,
J:SOO.Io
:!BJ(l:lt
:!J:Z07,
:!.tt.d.
J01l5t
J:!h60.
369.40,
37777.
31316.
.
nEG, ZJtl9Al 8!1•TIOH PI!H f'RO.IF'CT Fl.OioiR (CARt f))
NOV ll~C .IAH FF.D HAR AF'R HAY .nm Jill. .. AUG liEF' .
161154. lJIH t. t:u:n a 1J ~57. ll:'i:'iR• . '0.4()8. ~~~~flOO, aC!:u:h u:;~:s7 •. 10!iJ71., :J9JJJ.
i24lO, 1;!5R4~ 12724. llSJ5, i (lR~J. : • ; }2. !$7.fJfl:i. 492:11. U:l:lJA, J0017i'. 6 .. 71\:.!o
20H'l. 1 ~.\90. 1.307'/t t:!a:!:s. 11049. h.l'f'4. ~~.~~~=~· 1l120S, 124?.\0, ll42~9;. IJ(}17B.
:'01109. J 7197. 1:1075· 1.~764. 1238~· ·u19.o, 7R92:\, j !3-t34. ua:st:s. 96R01a <\416ft,
171105. 1:!1H2. 1<400~. lOA H. 1 u (12. ,lt()O\\t !'51997. 9JAHl. i09:l2R, 122275. 6:1796.
1JJRJ, 13431. J:tNi'i, i HJJ, 11 H9~ J!OA9o 51\59~. 14lJ5R:f • t:f44J4. J19Q44. :;:~:;o.-.
l6310t 150H o • · IJ261. U741. 1?.401. 1~.u2. 747Hh JJU5Blo l:19Mi1. l J l ~:'0 • 'Hl4:t 1 H.
21!641. ~11.2~~. J 70'i'1' 13791· il tH, t<~JIJJ, • 58 lfl-4. 1 !1:i3:U l 1~~9959. J 'H:Jllt. • a7n;!~.
24JJOe l7(ll(ij. 1Jfl72 •• lJ91:St 1~371. 1 :•JH!'S; MH:S~. 9~1H, 112:l67 •• 9Y:\23, ~J05lt
15:!5<\t i~46<\o H6t7. t2279. 11740, Jl:2.;t~. !516J:i. 9~&?2. !34571. l2947Bt 67904.
f!lJIB, Hciv7 •. 13161. I J 71Hlt .JlJU, 10347. 4ZHOo 7:]UJ, U9H.ot, 109666. 772:S2t
t794:S. ::.!(1532. HJ704, Hi:\06, 14!)31. 1JJB4o 16903. lJJ;o~a. t33774. llh~97. 62:"104·
Hll:Sl, 1:'i9B9. tsn~. U5J7. 114AO, 1071.1, 4BJJ9, i:t42864 t<\JH 1. t~U2J, • 1JiR06 •
t5Ao'1. 15904. 15l'?J. AJ'lt.il. ltRf19, lOJfiR, 4;'719. 693'l~S. t:HB02, ! OcHOA, 7078?.·
1'72Rth 13:?09. i JJ6fJ. !161R, ! '017. lOS .. ft. J71H• 11473.1. 123349. 9!.!:?H<lt HUOt
!54/,0, 1:SAJ2, 13957. l20AO. l'J11QJ, ll !lOS, -43/thR. ?32:iio; 1~1J96l. lll!.1:U • B9H4 •
1Bll4a 16iJ7· J~RH. fJ t 40. 12912. 12:l;;'Oo 50J~(l. t<l:tc\5~ l UOEJ21. J16?H, 63987.
1761o:!. 1494S, '"""9· l;1:t7:1. 125//.t 1<10li6. :i07:15t 1 H:;a:;, 1~3l!!ii!o tJ1:111l. '»9:1~7·
21316. 22172. l1R:i9o 1A59Rl t :svn • 12774. ij{I4J9. u~:;u, t24J:?Ot OAR76t 4'2Jf15,
12720. 12:snA~ !~3--Ha t 1 ?..~n. J 1.~93. 10066. 40:!01., . 1J~3 t t '9R2~0, 1\;t,lloR, .3409:it
l25H, 1J~R9t tJna ... 12l:S7t t:1.4BO, 1099:1. 19194. 9496(. 12J!S9lt I UaJ!1• .llO:'ili:it
19RRfla tJ9oa. H:ZJO, s:sou. l:4'92l· tts:so. J:SORJ, 99f}ff~. in99t. 1207:5 .... 66-tl:it
lllfd.;!. .1.1910. 1Jio41t !:S4JJO, l ~~!i'/ ~. 117!!0. &;i.\46, t5.1JU • 1328 ~I), •1 U&/0:1, · 59:44:1•
19819. J<4R94,
15670· 1~0110;
15221. l!'i::!O~.
H476. 12246.
2:!fl7!;!, 1Afl40o
15896. 12499;
19977. 14901.
17572. .t5037o
l3451t ll'i'BBe tOA60t HUt. 6(59Bo !Ol674o U7540t lO~~·U•
lJ-407. J1!'137. HQU, 10.149' :s;-:! 1-i. 57-t•H, •. 96&44. 8025.2.
1J99!'it 1J778e IJ:?52 I H746o -4 l4 51 • 106870·, i!.l!U:?• 913AO•
J~Ot~. lUMJ. 1.1598. 11759. 66807, ?15~9.' lOB69'7, 9R1Ue
151:S4t l~R!\~lt 1«167&. 'i'46J." S~9~!tl. 1390V'i'• 1:JJ91)9. 124tJU9t
UJBJ, UJ91. 12005. 1117~. 42530. 7799'}, 109171. 10:!100t
14R07o 13541. ' lUAO, . 12987. ,14045. .toua:•· UO!'i34 • 128:!01), .
1423~ •. 1~5i;.,\, 120!'57. 11441. 55~i7. 105105. .,:l073t lOfj:lfMa
TABLE 3.10 Susitna River at Susitna Station
Post-Project Monthly Flows (Case D)
45,~7.
3~RHt
7367,.
48910.
91.994.
5~500.
74J4G,
6:iUJa
YR A\10
4:1140.
409!$A,
49109.
4A942.
4:\:!Jfl,
50A9\o
:'i'l39,. z::~
5116:-i?t u:so:;.
49:?49·
4Jilf11,
:f4792.
S19'i'5o
H9l2·
441J2t
471>27. .. ,~ .. :;.
:1'2-tfllh
5009!h
:U19R•
46Jl1t
U~RO •
5'-7.H •
4:-il~R.
Jb116.
449~J.
43179,
!S 4l.i 9 ..•
H551H
!i;!S-4A•
October
November
December
January
February
March
April
May
June
JuJy
August
September
Annual
TABLE 3.11
RELATIVE CONTRIBUTION OF FLOWS
AT SUSITNA-CHULITNA-TALKEETNA CONFLUENCE
(PRE-PROJECT)
Flow Contribution by Percent Flow b
Chulitna 1 Talkeetna 1 Susitna 1
Total
Flow D/S
Talkeetna Chulitna Talkeetna
4859 2537 5639 13035 37% 20% .
.
1994 1187 2467 . 5648 35% 21%
1457 838 1773 4068 36% 21%
1276 671 1454 3401 37% 20%
1095 565 1236 2896 38% 19%
976 492 1114 2582· 38% 19%
1158 557 1368 3083 38% 18%
8511 4176 13317 26004 33% 16%
22540 11910 27928 62378 36% 19%
26330 10390 23853 60573 44% 17%
22190 9749 21479 53418 42% 18%
11740 5853 13171 30764 38% 19%
8748 4086 9567 22401 39% 18%
1 Discharge data from U.S.G.S. records.
I-
I
I
I
I
43%1
44%1
43%
43%1
43%
43%1
43%1
I
I
I
-1
I
I
I
I
I
I
I
••
I
I
I
I
-1
~··
I
I
'I
I
TABLE 3.12
RELATIVE CONTRIBUTiON Of FLOWS
AT SUS1TNA-CHULITNA-TALKEETNA CONFLUENCE
(POST-PROJECT, CASE A)
Flow Contribution by Percent Flow by
Chulitna 1 Talkeetna 1 Susitna2
Total
Flow D/S
Talkeetna Chulitna Talkeetna
October 4859 2537 T788 15184 ~2~ ..., 0 17%
November 1994 1187 9452 12.633 16% 9%
December 1457 838 11930 .14225 10% 6%
January 1276 671 10574 12521 10% 5%
February 1095 565 8943 10603 10% 5~ 0
March 976 492 8137 9605 10% 5%
April 1158 557 7990 9705 12% 6%
May 8511 4176 10418 23105 .37% 18%
June 22540 11910 12061 46511 48% 26%
July 26330 10390 10220 46940. 56% 22%
August 22190 9749 9553 41492 53% 24%
September 11740 5853 7711 25304 46% 239: Qc
Annual 8748 4086 9573 22407 39%
1 Discharge data from U.S.G.S. records.
2 Based on 30 years of simulated power operation~.
r31/c 3 -17
Susitna
51%
75%
84%
85%
85%
85%
82%
45%
26%
22%
23%
31%
43%
f. • • • ~ • • • ~ • .. .: ·: • • ' I "'-. . : .
TABLE 3.13
RELATIVE CONTRIBUTION OF FLOWS
AT SUSITNA-CHULITNA-TALKEETNA CONFLUENCE
(POST-PROJECT, CASE D)
Flow Contribution by Percent Flow b
Chulitna 1 Talkeetna 1 Susitna2
Total
Flow D/S
Talkeetna Chulitna Talkeetna
October 4859 2537 6901 14297 34% 18%
November 1994 1187 7380 10561 199: • 0 11%
December 1457 838 8595 10890 13% 8%
January 1276 671 7779 9726 13% 7%
February 1095 565 6765 8425 13% 7%
March 976 492 6851 8319 12% 6%
April 1158 557 5830 7545 15% 8'?. ;0
May 8511 4176 8071 20758 41% 20%
June 22540 11910 9335 43785 52% 27%
July 26330 10390 14996 51716 51% 20%
August 22190 9749 19924 51863 43% 19%
September 11740 5853 12371 29964 39% 20%
0
Annual 8748 4086 9567 22401 39% 18%
1 Discharge data from U.S.G.S. records.
2 Based on 30 years of simulated power operations.
r31/c 3 -18
···1~ -· --·-. \ '"~.,-•· -: ·.~. "Q •••
,,
I
I --
1
I
48% I
70% I
79%
so% 1
80%
82% I
77% I
39%
21% 1
29%
38% •.
41% I
43% 1
I -.
I .
I
I
,. --' '.· . .
1'·1
II
II
"·
I
I
I
I
••
I
I
I
I
I
I·
I
I
I
I
'·: .r~: ·;;, ·. _, ... --·
.-· . ~ .. -.
Recurrence
Interval
2
5
10
25
Recurrence
Interval
2
5
10
25
Recurrence
Interval
2
5
10
25
Recu-rrence
Interval
:-~-
2
5
10
25
Recurrence
Interval
2
5
10
25
TAllLE 3.14
ESTIMATES OF PRE A:W POST PROJECT
DISCHA'f;(GE AND STAGE llREQUENCY ANALYSIS
Devils Canyon Dam~ite
Preproj ect Postproj ect
Q
(cfs)
47,000
61,000
71,000
84,000
Revised
Q
(cfs)
11,000
12,000
13,000
28,000
Susitna River at Gold Creek
Preproject Postproject
Q Stage Q Stage
(cfs) (ft) (cfs) (ft)
49,500 13.4 13,500 8.7
66,000 14.9 17,000 9 .. 6
78,000 15.8 20,000 10.1
94,000 16.7 38,000 12.3
Susitna River at Sunshine Station
PreE_roject Postproject
Q Stagt; Q Stage
(cfs) (ft) (cfs) (ft) .,..."':•(<,..._.._
95,000 12.5 59,000 9.3
124,00() 1!~.8 75~000 10.8
144,000 16.3 85,000 11.7
174,000 18.4 118,000 14.3
Susitna River at Sunshine Station
:Pre;Eroject PostEroject
Q Stage Q Stage
-~cf:s} _ (ft) (cfs) (ft)
105y000 94.6 69,000 92.7
138,000 ·95.6 89,000 94.0
159,000 96.3 101,000 95.0
193,000 97.3 137,000 96.0
Susitna River at Sunshine Stat;Lon
Pre;Eroject Post;Eroject
Q Stage Q Stage
_jcfs) (ft) (cfs) (ft)
157,000 16.7 121,000 14.8
206,000. 19.3 157,000 16.7
239,000 20.9 181,000 18.0
289,000 23.0 233,000 20.5
3-19
. --
Change
In Stage
(feet)
-4.7
-S .. Ei
-5.7
-4.4
Change
In Sta.ae
(feet)
-3.2
-4.0
-4.6
-4.1
Change
In Stage
(feet)
-1.9
-1.6
-1.3
-1.3 .I
Change
In Stage
(feet)
-1.9
-2.6
-2.9
-2.5
r30/F1
TABLE 3.15
LOWER SUSITNA RIVER BASIN CHARACTERISTICS
FOR MEAN ANNUAL FLOOD CALCULATIONS
Drainage Area Glacial Area Forested Area Lake Area Mean Annual Mean Annual Mean Minimum Stream
Precipitation Snowfall January Temp. Length
D.~. G F LP M.A.P. M.A.S. J L
(mi. ) (%) (%) (%) (in.) (in.) (Of •} (mi.)
Susitna River at 19,400 12 23 2 43 167 -4 301
Susitna Station
Local Area: Susitna Station 640 1 60 5 30 70 0
to Delta Islands x-section
Skwentna River nr. 2,250 16 34 5 43 140 -5 98
Skwentna
Yentna River nr. 3,930 20 12 4 50 150 -5
Susitna Station
Delta Islands x-section 12,580 9 23 41 182 -3 281
Local Area: Delta Islands 1,080 60
x-section to Sunshine
5 ?O 70 0
Susitna River at 11,500 10 19 42 193 -4 224
Sunshine
(.,.> Local Area: Sunshine 764 0 90 2 30 50 0
I to Talkeetna N
0
Chulitna River 2,570 27 22 1 55 250 -5 87
Talkeetna
Talkeetna River nr. 2,006 7 25 0 . 70 150 -2 90
Talkeetna '
Susitna River at Gold 6,160 5 7 29 200 -4 189
Creek
Local Area: Gold Creek 350 0 0 20 0
to Devils Canyon
Devils Canyon 5,810 5 7 29 200 -4.
.~ I 1 • t ~ ~ 1, ?l 'r: c~
] <C<~ J I J
i~ l ~ ~ ~ I
1i
] , ) J 1 i
r30/g1
Susitna River
at Gold Creek
Chulitna River
near Talkeetna
w
I
N Talkeetna River I-'
near Talkeetna
Susitna River at
Susitna Station
Susitna River
at Gold Greek
Chulitna River
near Talkeetna
Talkeetna River
near Talkeetna
Susltna River at
Susitna Station
j ~
! j j
i .J 1 j
lJ
TABLE 3.16
MONTHLY AVERAGE RATIOS
) -J
(1-DAY HIGH AND 1~DAY LOW FLOW)/(MONTHL Y FLOW)
1 ~Day High Flow Ratios
Month!~ Average ~Standard Deviation)
May June July Aug.
2.45 (1.33) 1.49 (0.27) 1.36 (0.18) 1.57 (0.33)
2.05 (0.38) 1.52 (0.29) 1.36 (0.22) 1.56 (0.28)
2.51 (0.76) 1.69 (0.27) 1.64 (0.49) 1.89 (0.62)
1.89 (0.44) 1.25 (0.05) 1.21 (0.07) 1.27 (0.06)
1-Day Low Flow Ratios
Monthl~ Average (Standard Deviation)
Ma~ June Jul)!: Aug.
0.26 (0.14) 0.68 (0.13) 0.78 (0.08) 0.65 (0 .13)
0.31 (0.15) 0.63 (0.14) 0.78 (0.07) 0.66 (0 .10)
0.24 (0.08) 0.61 (0.11) 0.72 (0.07) 0.59 (0.08)
0.25 (0.10) 0.74 (0.09) 0.82 (0.05) 0.64 (0.05)
) 1 j J
Sept. Oct.
1.61 (0.32) 1.66 (0.39)
1.72 (0.39) 1.81 (0.38)
1. 91 (0. 51) 1.64 (0.26)
1. 58 (0. 18) 1.69 (0.27)
Sept. Oct.
0.66 (0.11) 0.59 (0.13)
0.62 (0.13) 0.58 (0.10)
0.63 (0.12) 0.62 (0.11)
0. 70 (0. 12) 0.60 (0.11)
• • ' , • _" .. "' • : ~ ~ • ' ' • , • ' ' ' • • ••
4
• 1 ", • ' • ~ • ' 9 ,_ • • • ' • • : : • • : ,
0
• ,.._ •, ' ....._ • ' • • '
0
• .• , -,
r30/g2
TABLE 3.17
MONTHLY AVERAGE RATIOS
(3-DAY HIGH AND 3-DAY LOW FLOW)/(MONTHLY FLOW)
w
I
N
N
')
May
Susitna ·River 2.24 (0.96)
at Gold Creek
Chulitna River 1.91 (0.31)
near Talkeetna
Talkeetna River 2.33 (0.60)
near Talkeetna
Susitna River at 1.89 (0.39)
Susitna Station
May
Susitna River 0 .. 28 {0 .. 14)
at Gold Greek
Chulitna River 0.33 (0.13)
near Talkeetna
Talkeetna River ',·· 0.24 (0.09)
near Talkeetna
Susitna River at 0.30 (0. 16)
Susitna Station
---
3-Day High Flow Ratios
Monthly Average (Standard Deviation)
June July Aug.
1.42 (0.23) 1.29 (0.16) 1.49 (0.30)
1.40 (0.19) 1.28 (0.15) 1.47 (0.26)
1.51 (0.22) 1.44 (0.30) 1.69 (0.45)
1.20 (0.05) 1.16 (0.05) 1.23 (0.07)
3-Day Low Flow Ratios
Monthly Average (Standard Deviation.2
July
0.71 (0.13) 0.80 (0.08) 0.67 (0.12)
0.66 (0.13) 0.80 (0.06) 0.68 (0 .. 09)
0.65 (0 .. 11) 0.75 (0.07) 0 .. 61 (0.09)
0.78 (0.08) 0.85 (0.05) 0 .. 68 (0.05)
Sept. Oct.
1.52 (0.27) 1 ... ss (0.31)
1.60 (0.29) 1: .. ss co.2s)
1.69 (0.37) 1 ... 53 (0.19)
1.45 (0.15) 1 .. 5'2. (0.23)
Sept. Oct.
0.68 (0.11) 0.61 (0.12)
0 .. 64 (0.13) 0.59 (O.lO)
0.64 (0 .. 12) 0~54 (0. '11)
0. 71 (0.12) 0 .. 63 (0 .. 11)
------· ~--~~~-----------------------·--------------------------------------------------------~--~.--~~
.-·
'
!
t J!j h
1 J J ) ' i
r30/g3
Susitna River
at Gold Creek
Chulitna River
near Talkeetna
Talkeetna River
w near Talkeetna
I
N w Susitna River at
Susitna Station
Susitna River
at Gold Greek
Chulitna River
near Talkeetna
Talkeetna River
near Talkeetna
Susitna River at
Susitna Station
~ i j
: ·~ j j
i
J
TABLE 3.18
MONTHLY AVERAGE RATIOS
) J ~ J
(7-DAY HIGH AND 7-DAY LOW FLOW)/(MONTHLY FLOW)
7-Day High Flow Ratios
Monthly Average (Standard Deviation)
May June July Aug.
1.87 (0.46) 1.28 (0.15) 1.17 (0.10) 1.33 (0.20)
1.75 (0.23) 1. 29 (0. 14) 1.19 (0. 08) 1.34 (0.17)
2.00 (0.39) 1. 32 (0. 15) 1.25(0.15) 1.43 (0. 27)
1.62 (0.33) 1.14 (0.07) 1. 09 (0. 04) 1.17 (0. 06)
7-Day Low Flow Ratios
Monthly Average (Standard Deviation)
May June July Aug.
0. 34 (0.15) 0.77 (0. 11) 0.86 (0.07) 0.74 (0.11)
0.38 (0.12) 0.73 (0.12) 0.82 (0.05) 0.73 (0.09)
0.30 (0.12) 0. 72 (0. 10) 0.81 (0.07) 0.68 (0.09)
0.42 (0.26) 0.84 (0.07) 0.90 (0.05) 0.76 (0.04)
J l i l l J j
Sept. Oct.
1.37 (0.18) 1.43 (0.23)
1.41 (0.17) 1.54 (0.20)
1.45 (0.22) 1. 38 (0. 14)
1.31 (0.12) 1. 34 (0. 16)
Sept. Oct.
0. 72 (0.10) 0.65 (0.11)
0.69 (0.12) 0.61 (0.10)
0.69 (o. 11) 0. 68 (0. 11)
0. 76 (0.11) 0.68 (0.13)
r30/g4
Susitna River
at Gold Creek
Chulitna River
near Talkeetna
Talkeetna River
w near Talkeetna I
N .p.
Susitna River at
Susitna Station
Susitna River
at Gold Greek
Chulitna River
near Talkeetna
Talkeetna River
near Talkeetna
Susitna River at
Susitna Station
.... J i I J I
TABLE 3.19
MONTHLY AVERAGE RATIOS
(15-DAY HIGH AND 14-DAY LOW FLOW)/(MONTHLY FLOW)
15-Day High Flow Ratios
Monthly Average (Standard Deviation)
May June July Aug.
1.51 (0.20) 1.13 (0.07) 1. 08 (0 .04) 1.16 (0.10)
1.48 (0.14) 1 .15 ( 0. 09) 1.11 (0.04) 1.17 (0.09)
1.53 (0.16) 1.15 (0.07) 1 . 11 (0.06) 1.19 (0.12)
1.38 (0.22) 1.06 (0.04) 1.05 (0. 03) 1.12 (0. 04)
14-Day Low Flow Ratios
Monthly Average (Standard Deviation)
May June July Aug.
0.48 (0.21) 0. 77 (0. 11) 0.92 (0.05) 0.83 (0.09)
0.50 (0.16) 0.84 (0.10) 0.89 (0.05) 0.83 (0.08)
0.45 (0.15) 0.85 (0.06) 0.90 (0.06) 0.81 (0.10)
0.61 (0.24) 0.92 (0.04) 0.95 (0.04) 0.87 (0.04)
' ' 1 ' -~ ' ~ ·~ ~ '!\
I
Sept. Oct.
1.19 ( 0. 08) 1. 26 (0. 10)
1. 22 (0 .10) 1. 32 (0.11)
1. 22 (0. 10) 1.23 (0.08)
1.17 (0.07) 1. 23 ( 0.11)
Sept. Oct.
0.82 (0. 10) 0. 73 ( 0.11)
0. 78 (0.10) 0.68 (0. 10)
0.79 (0.11) 0.76 (0.09)
0.86 (0. 10) 0. 78 (0.14)
1\ ] ' ~-
,-..-.,.,
TABLE 3.20
r-
""" AVERAGE RATIOS OF ANNUAL
DAILY LOW FLOWS TO ANNUAL MONTHLY LOW FLOWS
~ '""
(~ 1-Day 3-Day 7-Day 14-D~ 30-Day 60-Day 90-Day """
Susitna River
near Cantwell 0.98 0.98 0.98 0.98 0.99 1.02 1.06
Susitna River
at Gold Creek 0.97 0.97 0.97 0.98 0.99 1. 02 1. 08
,_,
Chulitna River
near Talkeetna 0.96 0.96 0.96 0. ~}6 0.99 1. 03 1.10
...
"""
Talkeetna River
near Talkeetna 0.96 0.96 0.96 0.96 0.98 1. 02 1.07
-~ ,,_
Susitna River
at Susitna Station 0.92 0.92 0.92 0.92 0.99 1.10 1.06 ·-
!~
r31/c 3 -25
Oct Nov Dec
!1&0 o.o o.o
o.o o.o o.o
(),O o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o J6·1 .2
o.o o.o o.·o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
w o.o .o. () o.o
I o.o o.o o.o
N o.o o.o o.o
()I o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o ·o.o
o.o o.o o.o
o.o 0;0 o.o
o.o o.o o.o
o.o o.-o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
J J J
Jan Feb Mar Apr May Jun
o.o o.o o.o o.o o.o o.o
1),0 o.o o.o o.o o.o o.o
o.o o.o o.o o.o o.o o.o
o.o o.o o.o o.o o.o o.o
o.o o.o o.o o.o 0 ,C) o.o
o.o o.o o.o o,o o.o (). ()
o.o .o.o o.o o.o 010 o.o
o.o o.o o.o o.o o.o o.o
o.o o.o O;O o.o o.o o.o
o.o -o.o o.o .o.-o o.o o.o
o.o o.o o.o (t,O OoO o.o
o.o o.o o.o o.o-o.-o o.o
o.o o.o o.o o.o o.o o.o
o.o o.o o.o o.o o.o o.o
o.o o.o o.o o.o o.o o.o
o.o o.o o.o o.o o.o o.o
o.o o.o o.o (I ,O o.o o.o
o.o o.o o.o o.o o.o o.o
o.o o.o o.o o.o 010 o.o
o.o 0•0 o.o o.o ().0 o.o
o.o o.o o.o o.o o.o o.o
(), 0 o.o. o.o o.o (),()
' o.o
o.o o.o o.o o.o o.o _, o.o
o.o o.o 1),0 o.o o.o o.o
0·0 o.o o.o o.o o.o Ch 0
o.o o.o o.o o.o o.o o.o
o.o o.o o.o o.o ·o. o o.o
o.o o.o o.o o.o o.o ·o.o
o.o o.o o.o o.o o.o o.o
o.o o.o o.o o.o o.o o.o
o.o o.o o •. b o.o o.o o.o
o.o b.o thO o.o o.o o.o
TABLE 3.21 Average Monthly Spill Below
Devil Canyon Dam
J I I ~ ' -~
-,o;, ~ '11 ~-
Jul Aug Se~ o.o o.~ (),.
o.o o.o o.o
o.o o.o (),()
(),IJ o.o C) • ()
o.o o.o o.o
(.1,() o.o o.o
0·0 J~t.6 o.o
o.o o.o o.o
o.o o.o (),0
o.o. o.o 0 ,.()
o.o o.o 0 .!)
o.o o.o o.o
o.o D90 ,5 o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o tl49. 0 o.o
o.o o.o (). ()
o.o o.o 0. ()
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o . 0. 0 o.o
o·.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o o.o o.o
o.o 3138.9 o.o
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DISCHARGE ·-STAGE FREQUENCY CURVES
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SUStTNA RIVER AT DELTA ISLANDS
PRE ·AND POST PROJECT
DISCHARGE-STAGE FREQUENCY CURVE
3-36
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4 -SEDIMENT REGIME
4.1 -Suseended Sedime~f
The concentration of suspended sed in~ 'nt in glacial meltwater
streams in Alaska is 10-20 times the concentration in nearby
non-glacial streams (Guymon, 1974). Most of the suspended
sediment is transferred during the summer months. The Susltna
River transfers over 98 percent of its annual sediment road during
the months of May through October (Corps of Engineers, 1975).
in general, there is no simple relationship between sediment
transport and water discharge in glacial meltwater streams (~strem,
197S). Suspended sediment concentration varies with time as well
as with discharge over periods of one year (seasonal) 1 one to
twenty days (flood sequence) 1 anq one day (diurnal). A
hystteresis effect has been observed by various authors (0strem,
1975; Everts, 1976) when the ratio of suspended concentration to
water· discharge was plotted by month or through a flood. Visual
inspection of sediment discharge records for the Susitna River at
Gold Creek indicate _a simHar phenomena, with large variations in
sediment concentrations with only minor increases in streamflow.
Despite the problems in reliably establishing a sediment
discharge streamflow relationship, some estimate of annual
suspended sediment discharge is necessary for engineering and
environmental studies. Consequently,-power curve equations were
fit to available data for seven stations within the Susitna River
basin~ The equations for each station are given in Table 4.1r
togetht~r with the coefficient of determination. The curves for
each station are plotted on Figures 4.1 through 4.5. On the
mainste·m Susitna, the ·sediwent concentration drops. for a given
flow when moving downstream, due to th-e· larger particles settling
ct!t and the larger volume of water downstream.
The annual suspended sediment duration curves for all seven
stations are plotted on Figure 4 .. 6. These were estimated . using
the annual flow duration curves and the suspended sediment r·atlng
curve for each station. Despite the fact that sediment
concentrations decrease while moving downstream, the total
sediment discharge is increasing due to the increas·ed flow volume.
4.2 -Bedload
Bedload data from the Susitna River was nonexistent until summer
of 1981. Three bedload samples have been coll~cted by the U.S ..
Geological Survey and R&M Consultants at Susitna River at Gold
Creek, Chulitna River near Talkeetna River, Talkeetna River near
Talkeetna, and Susitna River at Sunshine. Bedload transport
rates for the three dates are shown in Table 4.2. Estirrate5 of
bed material size distribution were made at numerous cross-sections
r29/a 4 - 1
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between 'Talkeetna and Devil Canyon, using· the grid sampling
technique {Kellerhals and Bray, 1971). The bed material size
distribution at these sites is tabulated in Table 4.3.
The U. 5. Geological Survey estimated total sediment load for ten
samples taken at the Denali gage using the modified Einstein
procedure. A bedload rating curve based on the USGS estimates
was established in the Corps of Engineers 1975 report and is
shown is Figure 4. 7. Using flow-duration curves, the Corps
report estimated the annual bedload at Denali to be 1,588,000 tons
per year. However, Neill (1981) has commented that bedload
computations for gravel rivers are not very reliable, with different
procedures producing estimates varying by orders of magnitude.
From the limited bedload data collected in 1981, it can be inferred
that the Susitna River has relatively little bedload below Devil
Canyon until the confluence with the Chulitna River is reached.
Most of the bedload is contributed by the glaciers in the Alaska
Range, althouLgh some is contributed by downstream tributaries and
bank erosion. All bedload entering the reservoirs will be trapped.
In addition, post-project flows will be less than that measured on
August 26, 1981, when only 380 tons/day of bedload transport
were measured. Most of the river between DeviJ Canyon and the
Chulitna confluence is well-armored. Under post-project
conditions, bedload contribution from the Susitna River above the
Chulitna confluence may be considered negligible cx~ept for
extrems flood events.
The Chulitna River is the major contributor of bedload at the
confluence near Talkeetna, as shown on Table 4.2, and will thus
have the major influence on sedimentation and river morphology at
and downstream of the confluence.
4 .. 3 -Reservoir Trap Efficiency
The volumes of Watana and Devil Canyon reservoirs are so large
that is has been assumed in past studies that 100-percent
entrapme 1t would occur. This is believed to be a valid assumption
for the larger sediment sizes, but it is possible that the very fine
suspended sediment may remain in suspension and pass through
the reservoirs. A literature search of sedimentation processes ~n "'
glacial lakes indicated trap efficiencies on the order of 65 to 75%.
(Zieler: J973; @strem, 1975). Kamloops Lake, a 3-million ac-ft
giacial lake in 5ritish Columqia, trapped an estimated 67% of the
incoming sediment, with median sediment size about 2 microns near
the lake· outle"t (Pharo and Carmack, 1979). The suspended
sediment size distribution analysis at Vee Canyon indicates that 85%
of the incoming sediment is larger than 2 microns. Kamloops Lake
has an annual bulk residence time of about .60 days. Watana
Reservoir has an annual bulk residence time of about 660 days.
r29/a 4-2
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The long bulk residence time in Watana Reservoir indicates that an
ice cover will probably form on the reservoir before the sediment-
laden river water can pass through the reservoir. Once on ice
covE•r forms, essentially quiescent conditions should occur in the
reservoir. A settling column study of a water sample from the
Susitna River indicated that suspended sediment concentrations
would ·decrease by about 9.5% in 3 days under quiescent conditions.
This would tend to int;;icate that clarity of water in the upper
portion of the reservoir should improve fairly rapidly once an ice
cover forms.
It is likely that trap efficiencies greater than 70% will occur, based
on suspended size distribution, annual bulk residence time, and
the suspended sediment settling characteristics under quiescent
conditions. For planning purposes, trap efficiencies of 70% and
100% were assumed as the :imits for trap efficiency. All bedload
will be~ trapped by the reservoirs.. The trapping of the bedload
wi II have the most significant Impact on the downstream river
morphology.
Reservoir sedimentation is discussed more completely in
Appendix 8.8: Reservoir Sedimentation (R&M, 1981).
4.4 -Bed Material Movement
The stability of a particle resting on the bed or channel bank is a
function of stream velocity 1 depth of flow 1 the angle of inclined
surface on which it rests and its geometric and sedimentation
characteristics (Stevens and Simons, 1971). However, the
interaction of the above factors is quite complex 1 and obtaining
data for all parameters is often impractical under natural
conditions. In order to determine at what flow rates the various
reaches of the Susitna River above Talkeetna would be stable, an
engineel"ing approach for the design of stable alluvial channels was
used.
Two major variables affecting channel design are velocity and
~hear stress. Determining the shear stress is quite difficult.
Consequently, velocity is often used as the most important factor
in designing stable alluvial channels. Various techniques have
been developed which estimate the maximum channel velocity so
that no scouring occurs for values of velocity equal to Oi'< less than
the maximum velocity. However, the maximum permissible
velocities varies with the sediment carrying characteristics of the
channel. Fortier and Scobey (1.926) recognized this problem 1 and
introduced an increase in their listed values of maximum
permissible velocities when water was transporting co!Joidaf silt.
Various engineering formulas for maximum permissible velocity were
presented by Simons and Senturk (1976). The formula selected
for analysis was· that derived by Neill (1967). N·eill 1s formula uses
r29/a 4 ~ 3
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data readily available for the Susitna River, and gives results in
the same range as Fortier and Scobey•s. The formula as presented
by Neill is:
where:
u =
~ =
es -
g --
0 =
d =
u2
(
_do\-0.20
2.5 ]
maximum permissible velocity, ft/sec
density of water, Jb/ft3
density of sediment, lb/ft3 (assumed to be 165 lb/ft3 )
gravitational constant1 32 ft/sec2
bed material diameter 1 ft
average depth 1 ft
The above stability criterion was developed for use on uniform bed
material or on the median (o50 ) size in mixedo bed material with
moderate size dispersion. Nein (1968) later indicated that the bed
mat~rial mlxtu:e re:mained fairly stsble until the o 50 size became
mob ale, at whtch ttme general movement of the bea would occur ..
The stability criteria was designed to use vertically-averaged local
velocities (mean column velocities), thus identifying bed stability
on only a short segment of the river cross-sectional width ..
However, only average velocity across each cross-section is
available.. The results from the equation would thus indicate when
bed movement across the entire cross-section is imminent. Bedload
normally does not move uniformly across. the width of a :river 1 but
is concentrated in a relatively narrow band. Therefore, the
results of this analysis are not strictly accurate, but do provide
an adequate indicator of bed movement occur~nce.
In order to estimate the o 50 size of bed material which would be at
the point of movement at" a particular cross-section for a given
flow rate, the above formula was re-arranged so that bed mater•ial
diameter was the unknown value. The average velocity and
average depth were obtained from runs of the H EC -2 model for
different flow rates. The formula in its re-arranged version is:
~29/a
u2.5
D=
464.43 d 0 •25
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Using the above formuJa and hydraulic:; parameters obtained from
runs of HEC-2, estimates were made of the median material size at
the point of movement at flow rates of 9 1 700i 17,000i 34,500; and
52,000 cfs. The median bed material size at the pofnt ·of movement
is described on Figures 4*8 through 4.13 1 working downstream
from Devil Canyon to Talkeetna. Included on the plots are the
bed material size distribution in the reach descrjbed on the
figures.. To assist in classifying the size range of sediment which
is being moved, a sediment grade scale is included on the bed
movement figures, The bed material movement curves are for
given cross-sections in each river reach. Table 4. 5 correlates the
cross-sections with river miles. Table 4. 4 gives average velocities
at selected cross-sections at the same flow rates.
By . comparing the bed material movement curves to the bed material
size distribution 1 predictions can be made of the effect of reducing
the streamflow, Le. reducing the mean annual flood from 52,000
cfs to 11,000 cfs. Once the median bed material size is moved,
general movement of the bed would oc~ur. In general, bed
material size ranges from coarse gravel to ~obble throughout most
of the river. Some movement of the mediar~ !•,.ad material size (from
the grid samples) could occur above 35,000 cfs throughout much of
the river 1 although these samples were primarily taken along the
upper shore. It is believed that an armor layer consisting of
cobbles and boulders exists throughout most of the river~
At 13,000 cfs, it appears that little bed material. movement wHJ
occur ln the main channel except in the region of river miles
124.5, 131.5 and 133 and near the confluence with the Chulitna
River, where bed material size is in the coarse gravel range,
somewhat smaller than in most of the rest of the river.
4.5 -Contribution of Sediment Downstream
Contributions of sediment downstream of DevH Canyon are
primarily from talus slopes, mass wasting, erosion of river banks,
and sediment contributed by tributary streams. The locations and
types of sediment sources between Devil Canyon and Talkeetna are
summarized in Table 4. 6. ·
r29/a 4 .. 5
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TABLE 4.1
SUSPENDED SEDIMENT DISCHARGE EQUATIONS
SUSITNA RIVER BASIN
... Station
Susitna River near Denali
MacLaren River near Paxson
Susitna River near Cantwell
Susitna River at Gold Creek
Chulitna River near Talkeetna
Talkeetna River near Talkeetna
Equation
q = 1 43 (10-4) q2.122 s .
q = 8.04 (10-6) q2.523
s
q = 6.33 (10-8) q2.784
s
qs = 2.39 (10-6) q2~354
q = 2.63 (10-5) q2~151 s ·.
Susitna River at Susitna Station q = 3 09 (10-6 ) q 2 ·146
s .
q = Streamflow, cfs
q = Suspended sediment discharge, tons/day s
r29/a 4-6
Number of
Samples
51
32
37
286
20
63
22
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Coefficient of '
Determination ( r 2 )
0.891
0.931
0.881
0 .. 735
0.948
0.832
0.885
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TABLE 4o2
1981 BEDLOAD TRANSPORT DATA
SUSITNA RIVER BASIN
Water Total Bedload
Discharge Transport Rate
Station Date (cfs) (tons/day)
Susitna R o at Gold Creek 7/22/81 37,200 2,180
Chulitna R 0
1 7/22/81 31,900 3,450
Talkeetna R o 7/21/81 16,800 1,940
Susitna Ro at Sunshine 7/22/81 89,000 3,520
Susitna R. at Gold Creek 8/26/81 25,900 380
Chulitna R. 8/25/81 22,500 5,000
Talkeetna R. 8/25/81 9,900 800
Susitna Ro at Sunshine 8/26/81 61,900 4,520
Susitna R .. at Gold Creek 9/28/81 8,540 1
Chulitna FL 9/29/81 6,000 3,820
Talkeetna R. 9/29/81 2,910 30
Susitna R .. at Sunshine 9/30/81 19,100 400
1 Bedload data gathered approximately 4 miles below Chulitna River
gaging site on 7/22/Slo Data gathered at Chulitna gaging site on
other dates.
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TABLE 4.3 -·
SUSITNA: LOVvER RIVER CROSS SECTIONS I BED: MATERIAL DISTRlBUTION ANALYSIS
LRX Number o16 (mm.) o 50 (mm.) o84 (mm.) I
4 13 25 46 .I
5 12 21 39
6 20 47 112 I 8 19 45 112
9 14 32 -u·\ n::.
10 58 94 152 J. 11 18 43 100
14 20 36 66
16 8 26 92
18 12 36 110 I 19 47 80 132
20 16 38 92
21 26 49 95 ••• 22 8 21 58
23 22' 48 108
26 25 54 113 ··-27 19 43 100'
28 13 31 68
29 32 59 110
30 33 64 122 ,,
31 '28 49 84
32 19 43 100
40 20 46 110 ·I "42 15 38 94
43 19 44 94
44 14 35 88
46 29 53 100 I 48 21 56 155
49 26 53 112
50 18 53 160 I 51 44 88 170
53 86 125 188
54 18 43 105 I 55 178 220 265
56 29 73 183
57 20 47 110
58 62 112 200 I 59 26 66 170
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TABLE 4.4
AVERAGE VELOCITIES AT SELECTED CROSS-SECTIONS
Cross
Average Velocities (ft/sec)
Given Flow Rates at Gold Creek
Section RM 9,700 17,000 ~4,500 52,000
LRX-4 99.6 5.27 4.32 4.78 4.47
LRX-7 101.5 3.15 3.86 5.31 6.09
LRX-11 106.7 2.53 3.60 5.64 6.89
LRX-20 117.2 3.15 4.13 5.13 4.86
LRX-24 120.7 3.80 5.34 8.25 10.34
LRX-25 121.6 4.71 6.94 7.99* 10.12
LRX-29 126.1 3. 71 5.04 7.66* 9.50
LRX-~35 130.9 3.52 5.04 8.12 10.44
LRX-40 134.3 4.12 5.43 7.67 9.29
LRX-41 134.7 ---· -. --~ .., .... 7.63 5.95* 5.71 :> • I I
LRX-44 136.4 5.54 6.'36 7 .13* 7.99
LRX-45 136.7 4.28 5.86 9.13 11.53
LRX-50 138.5 3.17 4.37 6.87 8.63
LRX-53 140 .. 2 3.83 5.01 7.62* 9 .. 56
LRX-54 140.8 4.53 5.72~ 6~93* 7.63
LRX-55 141 .. 5 3.55 . 4~66 6 .. 63* 7.77
LRX-61 148.7 4.25 5.67 8.64 10.45
LRX-68 150.2 3.24 4.54 7 .. 21 8.89 ..
* Sloughs and/or side channels are blocked off below 20,000 cfs
by gravel berms at upstream end.
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TABLE 4.5
SUSITNA RIVER PROFILE DATA SUMMARY
CROSS RIVER THALWEG
SECTION MILE ELEVATION
LRX-3 98.59 332.6
4 99.58 344.4
5 10\1.36 352.6
6 100.96 357.1
7 101.52 359.4
8 102.38 364.1
9 103.22 366.6
10 104.75 386.2
11 106.68 401.0
12 108.41 414.4
13 110.36 426.5
14 110.89 437.2
15 111.83 446.1
16 112'"34 449.7
17 112.69 453.4
18 113.02 452.9 .
19 116.44 481.7
20 117.19 483.3
21 119.15 500.9
22 119.32 503.4
23 120.26 515.5
24 120.66 507.6
25 121.63 526.2
26 122.57 532.1
27 123.31 533.8
28 124~41 549.8
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CROSS
SECTION
LRX-29
30
31
32
.33
34
35
36
37
38
39
40
41
42
0
43
44
45
46
47
48
49
50
51
52
53
54
55
TABLE 4.5 (cont.)
RIVER THALWEG
MILE ELEVAT,ON
126 ... 11 563.3 .
127.50 578.4
128.66 586.8
129.67 597.2
130.12 607.0
130.47 608.9
130.87 605.5
131.19 614~0
131.80 618.8
132.90 634.7
133.33 641.5
134.28 650.0
134.72 655.3
135.36 663.9
135.72 657.6
136 .. 40 674.6
136.68 673.5
136.96 681.4
137.15 681.9
137.41 685.3
138.23 694.2
138.48 693.5
138.89 701.9
139.44 707.2
140.15 717.2
140.83. 726.3'
141 .. 49 735 . .(~
4-11
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CROSS
SECTION
LRX-56
57
58
.. 59
60
61
62
63
64
65
66
67
68
TABLE 4.5 (cont.)
RIVER THALWEG
MILE ELEVATION
142.13 7tq.4
142.34 745.5
143.18 756.9
144.83 775.8
147.56 808.5
148.73 819.5
148.94 822.3
149.15 827.2
. 149.35 825.4
149.46 836.1
149.51 837.2
149.81 840.6
. 150~ 19 829.6
4 -12
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TABLE 4.6
SEDIMENT SOURCES DOWNSTREAM OF DEVIL CANYON
Location
Vicinity of RM 149.5
l·sland at RM 149.3
Downstream of Island
Mouth of Portage Creek
Vicinity of RM 148
Island at RM 147
Oo\vnstream of Island at RM 147
r29/a
Sediment Source and Type
Talus slopes delivering material at each
steep narrow . r·avine. Valley walls
controlled by bedrock outcrops.
Cobble and gr·avel material on
micjchannel .bar at river expansion.
Island surface . paved with cobb!es and
bo·ulders, intermixed with sand and
gravel. Bedrock controls both river
banks~
Bedrock controls both banks, but some
talus slopes delivering material.
Creek is delivering coarse gravels 1
cobbles, and a few boulders, davetoping
an alluvial fan into the river. Fan is
truncated where Susitna River flow
becomes significant. Significant bedload
delivered at high flows. . .
Local change in river gradient has
caused formation of a mid-channel bar
in the river exp2nsion ..
I stand is well vegetated above normal
high water, with its banks paved with
cobbtes. Some sand deposition exists in
the backwater zone on the downstream
end of the island.
AIJuvial deposition exists on the right
bank where the main channel is abutted
against left bank.
4 -13
Location
RM 145.3
Tributary on left bank
at RM 144.8
RM 143
Near RM 142
Upstream of RM 141.5
RM 141 to RM 139
RM 138.9
r29/a
Sedi.ment Sourc;~ and Tyee
Some erosion along the main channel
exists 1 along with mass sJurnping. A
mid ... channel gravef bar exists where the
river has eroded laterally; widened 1
reduced its veJocity and depo:..ited
bedload at high flows. The bar may
continue to grow, forcing the channel
into the right bank. ·
30-foot wide stream is very stable with
vegetation leading down to a
predominantly boulder/cobble bed. It
does not deliver significant sediment to
the river.
Moderate erosion and scalloping of the
right bank.. Several mid-channel bars
exist, but appear to be unstable, with
young brush growing on them.
River is trying to erode into the island
on left bank downstream of LRX-56.
Gravel is being deposited in the center
channel and trying to create a spHt
channel configuration ..
Acitve erosion of the island on the left
bank of the main channel. The river is
undercutting the bank, causing
slumping ·into the river 1 with the
sediment being only temporarily held by
coarser material and vegetative roots.
A mid-channel gravel bar is building.
The river is meandering across the
vaHey, eroding valley wall material and
depositing it on mid-channel bars ..
Glacial/fluvial deposit of gravel and
cobbles on the right bank appears
erodible at high flows. Topsoil over
the gravel alluvial deposits would er.ode,
at high flows 1 although lt is stabili~ed
with vegetation ..
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Location Sediment Source ·and Type
Mouth of !ndian ~River Indian River is a steep stream capable
of contributing considerable · bedload
during high flows, although there is no
glacial input.. Material near its mouth
is coarse gravel and cobbles, as smaller
material is carried away by the Susitna
River. The cobble material helps
stablii?.e the right bank of the Susitna.
Ari alluvial fan has been built out into
the Susitna River, forcing it into the
south val!ey wall.
RM 138.3 Moderate to active erosion along the
left valley wall for approximately 1, 000
feet, leaving a cobble pav~d bank ..
RM 137.2 Moderate to active erosion on the right
bank on an outside bend, extending for
about 1,000 feet.. Erosion occurs at
high flows; at normal flow 1 cobble
material armors the bank, resisting
erosion.
Mouth of Gold Creek Gold Creek bed is paved with boulders.
Downstream of Gold Creek bridge Moderate to active erosion of topsoil and
gravelly material along the right bank.
, Primarily, though, the river is
reasonably stable, with shallow sloughs
and gently sloping gravel bar·s along
the left bank. At high flows, there
will be some scour and deposition in the
high water channeJs.
Between RM 135~4 and RM 134 The valley wall is being eroded by the
left bank high water channel,
contributing a moderate amount of
sediment during high flows.
r29/a 4 ... 15
Location
RM 134.3
RM 132.5
Mouth of Fourth of July Creek
Sherman
RM 130
RM 128
RM 124
RM 123.5
Curry.
r32/b
Sediment Source and Type
Active erosion and undercutting of the
past alluvial deposit on the right bank
to just downstream of LRX-40. There
is also moderate erosion of the steep
high bank on the left bank, with
vegetative mat overhanging the bank.
Erosion extends for about 1, 000 feet
along the left bank.
Erosion of sand and gravel on a
mid-channel bar is causing short-term
local transport of bed materials.
Little sediment build-up at the creek
mouth indicates that the creek does not
carry much sediment. The creek slope
is relatively gentle as it enters into the
Susitna River.
The channel is constricted by alluvial
deposits on both banks, with the bank
lines well armored with cobbles and
boulders, resisting erosion.
A few areas of instability are located
along the intermediate gravel bar.
The river broadens into a braided
pattern, with the main channel
meandering from the west to the east
edge, causing unstable intermediate
gravel bars.
Moderate erosion and slumping of fine
material for about 800 feet along the
left bank.
Active erosion a tong the right bank.
Although the left bank is an alluvial
deposit, it appears quite stable.
4 -16
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Location
Curry to RM 116.4
RM 116.4 to RM 103.2
RM 103.2 to RM 102.4
RM 102.4 to RM 101.5
Mouth of Whiskers Creek
r29/a
Sediment Source and Type
A typical split-channel condition exists
in this reach, with no unusual erosion
or breaks in the river grad.ie:nt.. The
river is very stable due to coarse bed
material armoring the bed and due to
well established vegetation above the
normal high water mark.
The river remains stable, flowing in a
well-paved bed with well-established
vegetation on the banks. Several large
remnant boulders are in the channel,
probably deposited from glacial
processes.
Erosion in this reach can occur only at
high water levels, as a cobble paved
bankline lies beneath two to three feet
of soil. The left bank at LRX-8 is
eroding at the outside of the meander 1
but only at high flows. Deposition is
occurring upstream and downstream of
LRX .. 8 along the ri{1ht bank.
The western floodplain elevation lowers
at RM 102, becoming more erodible.
The channel splits and start to meander
in the braided/split channel pattern.
The shifting channels .appear to be
caused by a sudden decrease in
gradient, deposition of bed material,
and erodible banks. The banks at
LRX -7 are moderately .erodible at high
flow ..
Bed material is cobble with a thin layer
of fine sediments. The creek joins tr;;
west sub-channel on the outside of a
meander, helping to keep Susitna
sediments away from the mouth., The
right bank mate.rials in the ·west
sub-channel have five to six feet of
fine material overlaying easily erodible
gravel.
4 -17
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Location
Downstream of Whiskers Creek
RM 101.0
RM 100.5
RM 100
RM 99.6
r29/a
Sediment Source and Type
Fine material overlaying gravels would
erode at high water Jevels. A
mid-channel bar covered with young
vegetation appears to be well
established, helping · to keep the major
sub-channel to the east.
The main channel JOtns the west
sub-channel. A scallop in the right
bank indicates turbulence during
extreme flows. Numerous gravel bars
appear with the river becoming wider
and shallower. Several examples of
cross-channel flow reflect the instability
of the bed through the Jower reach.
The floodplain elevation Jowers, with
bank material appearing easily erodible
at moderate to high flows. Bank
erosion in this reach is ctccelerated by
undercutting of trees which fall into the
river, creating sweeper~;, turbulence
and niching of the bank.
The west side of the channel is in a
very unstable condition. Easily moved
bed material creates numerous gravel
bars which catch debris, forcing the
river to create new channels which are
constantly moving back and forth.
Along east bank, erosion will probably
occur only at high flows. An ice jam
occurred here in 1981, and is believed
to occur virtually E!Very year.
Vegetation along the banks is primarily
controlled by ice action.
4 .... 18
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Prepared by:
---.. ___ . ___ _
SUSPENDED SEDIMENT RATING CURVES
SlJSITNA ,RlVER NEAR DENALI AND :
MACLAREN RIVER. NEAR PAXSON FIGURE 4.1
-
.... -.. ----~. .... --
I
1,000
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4 5 6 7 8 9 10,000 2 3 4 5 6 . 7 8 9 100,000
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SUSPENDED SEDIMENT DISCHARGE (TONS I DAY)
SUSPENDED SEDIMENT RATING CURVE
SUSlTNA .RIVER NEAR CANTWELL (VEE. CANYON)
________ .. _ . ---------
I ..
!
~
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R&M CONSULTANTS • .lNC.
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SUSPENDED SEOIMEN.T DISCHAR~E (TO.NS /DAY)
SUSPENDED SEO·I~1ENT RATING CURVES
SUSITNA RIVER AT· GOLD CREEK
I I • I I I
2 3 4 5 6 7
Pr ared for:
·.
FIGURE 4.3
----------.. --.. .. .. ----
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R&M CONSULTANTS, INC. CHULITNA AND TALKEETNA RIVERS
10 FlGURE 4 .. 4.
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~~2 Mi SUSPENDED SEDIMENT RATING CURVE
SUSITNA. RIVER AT SUSITNA STATION . R&M CCNSU.\..TANTS. INC:•
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.... ----
./ FIGURE 4 .. 5 All~
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PERCENT OF TIME SEDIMENT DISCHARGE EXCEEDED
..
R&M CONSULTAI\ITS. INC •..
ANNUAL SUSPENDED SEDIMENT
OU RAT I ON CURVES
·c:::=======-------..:4:.:-2:..4 ~~,__ ____ FIGURE 4.6 ~~~(~
----.. -.. --.. .. " -----
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T
11-ITERIM REPORt
SOUTHCENTRAL RAlLBELT
AREA, ALASKA
ALASKA DISTRICT
-
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PREPARED ~y I SEDIMENT OISCHA~GE,,_ !tL.JOJ:~S/DAY --------~----~-PREPARED FOR~
··---~ .. _.,__ . .,.._, __ .,,., __ ..,_
EST I MATED BEDLOAD
SUSITNA RIVER AT
RATING
DENALI
CURVE
---
VERY FINE
GRAVEL:
- --------~~~ ____________ _, _______________ -===:==!llle!!!!!!!!!!l!!l!l!ll~
--~-----.. ----
.
BED MATER1AL MOVEMENT CURVES
LRX -54, -~7,·-62,-68 ..
---
LARGE COBBLES
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PREPARED BY t
BED MATERIAL MOVEMENT CURVES
LRX -36,-38,-39,-40
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PREPARED BY •
BED MATERIAL MOVEMENT CURVES
LRX-28 -29-31 -35
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PREPARED BY •
20 40 60 80 100 120
MAXIMUM BE:D MATERIAL DIAMETER MOVED, MM
BED MATERIAL MOVEMENT CURVES
LRX-l6 ,-18 ,-20,-24
140 160 teo
PREPARED FOR•
I
-•. --- - --- - - - - - - - - - -..
LARGE COBBLES
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5 -QUALITATIVE ANALYSIS
5.1 -Response Relationships
Hydropower development in the upper Susitna Basin wifl change
the sediment and flow regimes downstream of the project until the
effects ar.e either diluted by tributaries or until related dominant
geomorphic processes override the project induced changes. Flow
of water and sediment are the independent variables which
determine river channel morphology, and for which the project will
establish a new regime for. The remaining channel dimensions,
shapes, patterns and hydraulic parameters will be forced to
respond and perhaps eventually establish a new balance.
Morphologic parameters that are depe:1dent. on and would respond
to altered water dischat·ge and sediment load include:
d -mean depth, determined by dividing the area by top
width
w -surface width of channel
w d -channel shape, width-depth ratio
S -Slope1 river gradient
D -bed material sizer o50
ML .. meander wave length
¥ -Sinuosity
When considering a specific river reach there is a defined pattern
that the river has developed or is striving to achieve. A pattern
change could occur if the independent inflow variables of sedim€nt
load and water discharge were changed. However, certain
constraints are imposed ontc the system which could predominate
and locally override both the independent and dependent variables.
The potential constraints consist primarily of remnants from past
ge9Jogic processes such as valley walls, bedrock outcrops, and
g1acial/fluvial processes.
Based on research results of Lacey (1929-30), Blench (1937), Lane
(1955), Leopold and Maddock (1953), Santos-Cayudo and Simons
(1972) and Schumm (1971), the following general statements
concerning a river's response to altered water discharge and
sediment load can be made.
(1) Depth is directly proportional to the cube root of
discharge and inversely related to the bed-material
discharge .
r30/a 5 -1
(2) Channel width is directly proportional to the square root
of discharge.
(3) Channel width is directly related to sediment load~.
(4) Channel shape (width-depth ratio) is directly related to
.sediment load. ·
(5) Meander wavelength is directly related to discharge and
to sediment load.
., (6) Gradient is inversely related to discharge and directly
related to sediment load and grain size.
(7) Sinuosity is related to slope and inversely related to
sediment load.
These qualitative relationships are used as guidelines in
determining potential changes to river morphology as a result of
flow and sediment regulation. The base premise of these
relationships is that the river has a full opportunity to form
channel(s) within its own sediments. Limitations on the Susitna
Rivers freedom of movement are discussed in the following
sections.
5. 2 -River Pattern and Channel Characteri·.stics
Control
Some 15,000 to 20,000 years ago, the Susitna River valley
betweeen Devil Canyon ·and TC=ll keetna was the route of glacial ice
flows. Recession of the glaciers formed some of the surficial
features present within the valley. Several of these remnant forms
and depositions impos3 controls on the river behavior and act as
an independent variable along with flow and sediment.
Presence of several terraces in the valley bottom indicate that as
. the ice receded 1 a larger quantity of water and sediment was
available and the older river bed was at a higher elevation. The
process of degradation through the periglacial deposits has been
by a preferential sorting mechanism, in that the river has moved
the small and medium sized particles down the system and either
formed temporary alluvial deposits within the floodplain or flushed
the n1aterial to and beyond Talkeetna. This process of
downcutting and reworking of the glacial sediments has developed
an armor layer of cobble sized material around the main channel
perimeter. ·
r30/a 5 - 2
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The presence of the armor layer around and along the river
channel is not verified by subsurface excavations. However,
numerous observations were made during the hydrographic surveys
conducted in the fall of 1980, when the watel"' level was low and
water dear. Exceptions assuredly do exist, but the armor layer is
a definite control feature of the system that limits or retards
channel movement.
Bedrock controls the river through Devil Canyon and intermittently
downstream to Curry.-Although no direct evidence exists that the
channel bed is on bedrock, it is believed to influence the river
gradient in some locations upstream of Gold CreeK. The more
obvious influence of bedrock on river behavior is along the valley
walls where the channel flows impinge on it. At several locations,
the bedrock limits movement on one side, thereby magnifying the
influence of processes that may occur along the opposite valley
wall. This situation exists at the confluence of several
tributaries. These steep gradient streams have delivered a
significant quantity of sediments to the Susitna mainstem and have
formed conical shaped alluvial deposits. Due to the steep gradient
of these str·eams, a portion of the material delivered by the
tributaries is larger than that which the Susitna normally carries.
Therefore, the progressive encroachment has. narrowed and
deepened the channel against the bedrock valley wall. These
constrictions establish hydraulic control points that influence the
flow of water, lee and sediment.
Several small tributaries have pronounced alluvial fans which h~v£t
formed on the valley bottoms. These depositional features ar~e
considered periglacial because of the established vegetation and the
incised channel. During deglaciation, abunda~ce of glacial de;:bris
and meltwaters-provided large quantities of sed1Ment to the valley.
Subsequent stabilization of the basin resulted in a $'"erltJction of
sediment, aUowing the streams to develop a channel through tl:-)e
alluvial fan. Presently these fans ar~ relativeiy stable and are not
expected to grow significantly. Dur-ing torrential· events,
· reworking of the deposits and episodic delivery of sediments can
be expected~
Patterns
Four t'!ver pattErns ara evident on the Susitna River: single
chann':·:.~, split channel, braided, and multi -channel.
Characteristics of aach ar·e shown in Figures 5.1 through 5.4.
These t~haructeristic patterns are used in Section 5.3 when
describing the various river reaches. In general, the Susitna
River ha.s either a single channel or spiit channel configuration
r!4b~··,ve the confluence with the Chulitna. Near the Chulitna
t:onfiuenc~, the SHsitna assumes a braided pattern for the
remaind-~:"' cf its length. In the reach from RM 61 to 42, a
combined /~~ttern is evident, with a braided pattern on the western
·r30/a 5 - 3
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tl L~---~-·:'~~·· \ ~~""'-'--"·j--'. G:::_·'c ~~~-·
,'
""'"""'>-.. ,., •• •'. ""
floodplain and a multi-channel pattern on the eastern floodplain ..
The pattern of braided rivers contrasts sharply with the pattern
of other common river types. An explanation for thls phenomenon
has been offered by several investigators (Fahnestock, 1963;
Leopold, et al., 1964; Leopold and Wolman, 1957; Mackin, 1948;
Henderson, 1966; Church, 1972) ~ Although each expfain~d
reasonably the cause of braiding with respect to the lndivid12al
study 1 the resulting conclus~ons nften conflicted with others. The
cause of braiding has been variously attr~buted by different
authors to ~bundant sediment . load, iarge and sudci.en discharge
variations, e~·odible banks, and high gradiepts. lt appears that
braiding resuSts from all of these char-acteristics ~rather than being
dependent on only one. l\1ollard (1973) developed a , scheme to
define the influencing factors on alluvial river patterns. This
· scheme expresses braiding as a result of high rates of bedload
transport, low channel stability, high sediment supply,-high
gradients and low upstream flow regulation.
5.3 Regime Analysis of Susitna River Reaches
Project released flows will vary considerably from the natural flow
regime. Generally the Susitna River at Gold Creek exceeds its
mean annual flow of 9,650 cfs during the months of May through·
September and drops to 1,000 to 3,000 cfs during the winter
months. At Gold Creek the mean annual flood {recurrence interval
of about 2 years) is 49,500 cfsf and for river reaches considered
to be in regime corresponds to bankfL~II flow. Bankfull flow is
regarded as the dominant discharge that shapes the river channel
to accomodate it. For the purposes of qualitatively assessing the
response of the river to regulated flow and sediment conditions.,
bankfull flow is often used as the baseline. Post project flows and
sediment loads wi!! be reduced significiantly below this baseline
and therefore wi II effect the dependent variables.
For example, a stable single-channel reach of the Susitna upstream
of the Chulitna confluence has a bankfull width of about 600 feet.
Assuming a dominant discharge equal to the mean annual flood,
49 1 500 cfs 1 and appiying a generalized form of Lacey's regime
width equation:
1
W = CQ'2
yields a value for C of 2. 70, very close to Lacey1s original value
of 2.67. Reversing the procedure for' a post-project dominant
discharge of 13,000 cfs yields a regimf~ width of 310 feet. This
relationship indicates that the project wiH result eventually in a
substantial narrowing of the chpnnel 1 nt.Jt only by abandonment of
side channels in multi-channel reaches 1 but also in w!dth reduction
in the main channel. Due to reduction in suspended and bed
sediment loads, this process will be vet .. y slow, covering many
decades or longer. .
r30/a 5 - 4
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Downstream of the Susitna and Chulitna River confluence a braided
river pattern prevails. Dominant discharge in a briaded system is
that which produces a stage that overtops the intermediate active
gravel bars. When this occurs the bed materiai is set in-motion,
and changes in channel network configuration and shape normally
result. Regul.:iting Susitna flow wUI reduce the frequency of the
threshold from a mean annual flood to a flood that would be
expected to occur with a recurrence interval of 5 to 10 years or
greater (Table 3 .. 14). Under post-project conditions, , the
f:requency of occurrence of dramatic changes in river morphology
wiH decrease, resulting in a more stabilized floodplain, decreased
number of subchannels and increased vegetative cover.
A summary of river patterns by reach is presented on Table 5 .. 1.
Each reach was defined by distinguishable breaks in bed slope and
observable changes in river pattern. A general decrease in slope
is associated with the downstream progression of the river with the
exception of the reach from RM 149 to RM 144. The gentle slope
through this reach indicates that bedrock may control the bed
gradient. The river profiles ·for the Susitna River and its major
tributaries are shown in Figure 5.5 and 5.6.
r30/a
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RM 149 to RM 144
Pattern
Through this reach, the Sl:J-sitna flow~ in a predominately singJe
channel confined by valley walls (Figures 5. 7 and 5. 8). At
locations where the valley bottom widens, deposition of
gravel/cobbjes · has formed mid-channel or sjde-chann~l bars.
Occasionally a vegetated island or fragmentary floodplain has
formed to a top elevation above normal flood levels, and vegetation
has become established.
Control Features
Frequent occurrence of bedrock outcrops along the valley wall
indicates that the river slope may be controlled by bedrock. This
hypothesis is further supported because the average slope from
the downstream end of De vi I Canyon to RM 144 is less than the
next downstream reach, and there appears to be no correiation
between the bankfull stage and mean annual flood. Presence of
cobbles and boulders in the bed material (Figure 5. 7) aids in
stabilization of the channel geometry.
Processes ___., .
Portage Creek JOins the Susitna at RM 148.9 and has formed a
gravel and cobble fan at the confluence& This steep-gradient 1
non-glacial stream delivers significant coarse grained sediment to
the Susitna. The Portage Creek fan geometry is depend ~nt on
Susitna stages and transport capabilities.
§.ummary of Potential Post-Project Morphological Changes
0
0
r30/a
The channel is stable, and little change in form is
expected.
Portage Creek fan will progress out into the Susitna
until equilibrium with the regulated Susitna stage is
estabHshed. Perching of the stream mouth is not
expected.
5 - 6
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RM 144 to RM 139
Pattern
A broadening of ~he valley bottom has allowed the river through
this reach to develop . a split channel form with intermittent
weH-veg(:tated islands (Figures 5.9 and. 5.10) A correlation exists
between bankfull discharge and mean-ar1nual flood.
Control Features
Where the main channel impinges on valley walls or terraces, a
cobble armour layer (Figure 5. 9) has developed with a top
elevation at roughly bankfull flood stage. At RM 1441 a periglacial
alluvial fan of coarse sediments confines the river to a single
channel.
Processes
Reworking of alluvial deposits is frequently evident through this
reach.. Erosion of islands is evident where a channel impinges
against the alluvial deposits. Frequent mid-channel bars,.
composed of gravel, are mobile during moderate floods. These
active bed sediments reform along with subchannel pattern
changes.
Summary of Potential Post-Project Morphological Changes
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Erosion of valley walls and terraces wHl decrease
dramatically due to the armour layer .
Reworking of alluvial deposits in the main channel will
continue but at a reduced rate.
Main channel form will progress slowly to a more uniform
sinuous pattern.
Subchannels may become inactive.
Tributary at RM 144 could become perched. It may not
be able to regrade its coarse bed sediments to meet the
regulated Susitna water level.
5 - 7
RM 139 to RM 129.5
Pattern
This river reach is characteristized by a well defined spiit channel
configuration. Vegetated islands separate the main channel from
the side chann-els. Side channels occur frequently in the alluvial
floodplain (Figure 5.12) and are deHvered Susitna water only at
fi~JWS above 15,000 to 20,000 cfs. Often, valley bottom springs
flow into sloughs. There is a good correlation· between bankfull
stage and the mean annual flood.
Controls
Where the main channel impinges valley walls or terraces r a cobble
armour layer (Figure 5.11) has developed with a top elevation at
roughly bankfull flood stage.. The main channel bed has been
frequently observed to be well armoured.
Primary tributaries include Indian River 1 Gold Creek and Fourth ·Jr
July Creek. Each have built an alluvial fan into the valley
bottom, constricting the Susitna to a single channel. Each
constriction has establishes a hydraulic control point that regulates
water surf?.ce profiles at varying discharges and . associated
hydraulic parameters.
The railroad bridge location takes advantage of the Goid Creek fan
constr·iction and further stablizes this constriction. One mile
downstream of the bridge, the main channel impinges the bedrock
valley wall and orients the river southward. Ice j~ms h~ve been
reported to commonly occur at this location, and backwater behind
the jams causes water to spill into the east floodplain 1 contributing
to the formation of the subchannels ..
Processes
.
Indian River joins the Susitna at RM 138.5 and has formed a
gravel fan at the confluence. This steep-gradient1 non-glacial
stream delivers significant coarse grained sediment to the Susitna ..
The fan extends several hundred feet upstream and downstream of
the present mouth. The stream gradient is dependent on the
Susitna stage and does not have difficulty in adjusting to a
variable Susitna stage.
The Gold Creek bed is composed of cobbles and boulders. The
mouth is presently very steep. Because the confiL•ence is at the
outside of a Susitna meander 1 Gold Creek bedload sediments are
readily transported l;?y the Susitna. This creek has difficulty
adjusting to a variable Susitna stage.
r30/a
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Fourth of July Creek has a relative gentle gradient as it fiows into
a Susitna subchannel. It is a non-glacial stream with a cobble
bed.
Comparison of 1951 and 1980 air photos indicates a few changes in
bank lines and island planform, but generally the channel
delineation is stable. Although visible evidence indicates that a
majority of the main channel ls welt armoured with cobbles, ther·e
are s:everal active gravel bars through this reach. A partial
sou ret. of this sediment is from erosion of alluvial deposits.
Currently 1 active erosion is occurring on the west bank between
RM 134 and RM 135. At RM 132.5, several active gravet bars
exhibit a braided river pattern. It has been observed that during
moderate flows, these mid-channel gravel bars erode and reform .
These processes indicate a long duration 1 small volume, but
relative continuous movement of gravel bed material. A common
feature associated with the beds of side channels and sloughs at
the bifuration point Is a cobble berm. These berms act as control
weirs 1 limiting delivery of main channel surface water to flows
greater than 15,000 to 20 1 000 cfs.
Summary of Potential Post-Project Morphological Changes
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indian River will continue to extend its alluvial deposits
into the Susitna. Indian River should easily grade its
bed to meet the regulated Susitna Stage.
Gold Creek gradient is presently very steep as it enters
the Susitna. The cobble and boulder bed will resist
regrading the bed to meet the regulated Susitna stage ..
Fourth of July Creek gradient is currently relatively flat
and should easily adjust to the regulated Susitna stage.
Erosion of valley walls, terrace deposits and alluvial
banks will reduce dramatically due to the armour layer.
· Reworking of active gravel bed materials will continue. at
a reduced rate. Main channel form wiH slowly progress
to a more uniform sinuous pattern.
Several of the sloughs and subchannels could be blocked
off from the Susitna main channel at the regulated stage.
Where these channels rejoin the Susitna, gradual siltation
and vegetation encroachment wHl occur.
5 - 9
RM 129.5 to RM 119
Pattern
River patterns through th;s reach are similar to those discussed in
the previous reach. Th~ most prominent characteristic between
Sherman and Curry is that the main channel prefers to flow
~gainst the west valley wall and the east floodplain has several
sidechannels and sloughs (Figure 5.14). The alluvial fan at Curry
(Figure 5.13) constricts the Susitna to a single channel and
ter·minates the above described pattern. A fair correlation exists
between bankfull stage and mean annual flcod through this reach.
Comparison of 1950 and 1980 airphotos reveals occasional local
changes in ban klines and island planf'orm.
Controls
The west valley wail is generally nonerodible and occasionally has
exposed bedrock outcrops. The resistant boundary on one side of
the main channel has generally for·ced a uniform channe!
configuration With a well armoured perimeter. The west valley wall
is relatively straight and uniform except at RM 128 and 125. 5. At
these locations bedrock outcrops protrude out and deflect the main
channel to the east side of the floodplain.
Processes
At RM 128 and RM 125.5, where the main channel crosses over to
the east floodplain, a tendency to braid is exhibited. The river
has an opportunity to increase its br•eadth, to d~crease its depth
and to deposit a portion of its bedload. The broadened channel
flows against the resistive east bank, regains its shape and
resumes its preferred western route. ·Jn comparing 1980 aerial
photos with 1950 photos, it can be seen that .similar processes have
been ongoing through this era. Some erosion of the east channel
alluvial deposits has occurred but no dramatic changes are
evident. There is moderate erosion of fine mater"ial along the left
bank near RM 124 (Figure 5.13).
Cobble berms at the bifurcation of subchannels and sloughs are
prev~lent through this reach. A possible explanation for this
phenomena may be as follows. Even when a river pattern appears
straight, such as when the main channel flows against the west
valley wall 1 streamlines will meander within the channel. This
process develops secondary currents that flow in a helicoidal
direction.. The total sediment load is dh·ected away from the hard
surface toward the opposite bank. Depending upon flow, local
hydraulics, and other controls, the sediment may either be
re-entrained -oro deposited along the bank. As the flow increases
and spills into the side channels, the coarser sediments are
delivered to the sidechannels. When the coarse sediment
r30/a 5 -10
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encounters a shallow channel with lower velocities, it witi drop out
and deposit. As flow recedes t the flow over the berm may
channeJize, developing a minor incised channel on the downstream
side of tr.e berm, and eroding a niche into it. This niche
provides a temporary waterway at moderate-flows.
The minor tributaries along this river reach afl appear to have
fairly stable, but. steep, basins. Contribution_ of sediment to the
river will be episodic during extreme precipitation events.. Of
prime importance is that the tributaries and springs will deliver
fresh water to the east subchannels and sloughs.
;Summary of Potential Post-Project Morphological Changes
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Erosion of valley· walls 1 terraces and alluvial deposits will
reduce dramatically.
At RM 128 and RM 125.5, reworking of gravel
material will continue, but at a reduced rate.
channel form will become more uniform.
bed
Main
Cobble berms at the side channels and sloughs will
con'tro'l and perhaps block main channel flow from
entev-i ng them .
The river should continue its preferred and stable route
along the west valley wall.
5 -11
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RM 119 to "RM 104
Pattern 0
Through this reach the river is a very stable, predominantJ)I
incised single channel pattern (Figure 5.16) with a few islands.
Control
The channel banks are well armored with cobbles and boulders
(Figure 5.15), and visual inspection indicate~ that the bed is also.
Several large boulders occur intermittently along the main-channel,
and are believed to have been transported down the valley during
glacial ice movement. They provide local obstruction to flow and
navigation, but do not have a significant -impact on channel
morphology.
Processes
The bankfull flow and the mean annual flood !:riteria do not appear
to apply to this-reach. Flow at 53,000 cfs is lower than i:h~
vegetated island and bani< elevations. 'It appears that ·this reach
is capable of transporting all sediment delivered to it. In
addition, this broad low-relief valley delivers little or no sediment
to the system. In effect, it appear$ that this reach acts as a
.conduit carrying the total·-sediment load through it.
Erosional and depositional processes are almost indetectable.
Comparison of 1951 and 1980 aerial -. photographs reveals no
significant changes in channel morphology. Gravel bars above the
18 1 000 cfs flow level appear to have the same form, with only one
exception at RM 114. There have been some changes in the
alluvial gravel deposits, minor erosion of the islands 1 and some
stabilization of the floodplain adjacent to the east bank. These
proc.c:~.sses are represent~tive of the system.
Summary of Post Project Morphological Changes
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( }
No consequential changes in the channei morphology are
expected.
5 -12
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RM 104 to RM 9S
Pattern
At the confluence of Susitna, Chulitna and Talkeetna Rivers, there
is a dramatic change in the Susitna pattern from a .split channeJ to
a braided pattern (Figures 5.17 and 5.18). Emergence from
mountainous confined upstream basins into the lowland unconfined
basin has introduced the ability of the river systems to develop
laterally. Ample bedload transport and a gradient decrease also
assist in establishing conditions to support the braidad pattern.
.
The Chulitna River has a similar mean annual flow as the Susitna I
yet its drainage basin is about 40 percent smaller. Its glacial
tributaries are much closer to the confluence than the Susitna, and
a majorlty of the Chulitna River1 s length is confined by rock valley
warls. As it emerges from the incised canyon 20 miles upstream of
the confluence, the river transforms into a braided pattern with
moderate vegetative growth \on the intermediate gravel bars. At
about a midpoint between the canyon and confluence, the Chulitna
exhibits a highly braided pattern .with no vegetation on
intermediate gravel bars and . evident recent lateral instability.
This pattern continues beyond the confluence and the impression is
given that the Susitna is tributary to the dominant ChuUtna River.
The split channel Talkeetna River is tributary to the dominant
braided pattern.
Control
Terraces generaJiy bound the broad floodplain but provide little
control over channel morphology. General floodplain instability
results from the three.~ river _system striving,. to balance out the
combined flow and sediment regime.
Processes
Referencing Figure 5.19 it can be seen that considerable movement
of channel boundaries has occured in the three rivers between
1951 and 1980. The background is 1980 aerial photography and
the dark lines delineate 1951 channel boundaries as defined by
vegetation limits.
In the Susitna River, there has been some lateral movement of the
vegetation lines, with both erosion and stabilization of alluvial
deposits with vegeta'tion. The river has maintained the basic
braided river pattern.
Since 1951 1 there has bee.~3 a progressive movement of the Chulitna
River main channel from the south edge of the ftoodptain towards
the north. As a result, a remark~t-;t~ amount of vegetated
floodplAin on the north bank has eroded. Continued movement to
5 ... 13
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the north is limited because the iateral migration is progressing up
the valley slope. During a mid-summer flood in 1981 1 the Chulitna
main channel relqcated from the north side of the floodplain to
near· the central floodplain. Cause of this change is unknown bt:Jt
could be related to the limited northward movement, debris
accumulation or some anomalie that occurred during the flood
event. The broad fan-shaped active floodplain gives the
impression that the Chulitna is currently aggrading. This concept
is further ~videnced by inundation of the established vegetation
aJong the north floodplain that is killing the spruce trees,.
Although not supported by field data, it appears that a rise in the
gravel floodplain bed has occurred recently. Glacier instability far
upstream could be the source of flow and sediment regime changes
that are influencing apparent instability near its mouth.
Continued measurements of bedload transport rate, elevations and
stage/discharge relationships will be required to determine with
confidence the stability of the Chulitna.
The TaJ keetna_ River has had several channel changes upstream of
the railroad, but the bridge and bank revetment have stabilized
the river as it enters the Susitna River.. ·rn 1979, the bankfine
around the village 01f Talkeetna was stabilized with rock riprap9
Preliminary bedload measurements indicate that the Chulitna is the
main source of bed-material transport and provides roughly
4000 tons pet day. Through the 90-day sun1mer flow period this
would produce 360,000 tons per year or a volume of 240 1 000 c.y ..
per year. Assu.ming that 50% of this were no longer transportable
by the reduced fl'ood regime downstream of the Susitna and was,
deposited over a h:!ngth of 10 miles on an active floodplain width of
3000 feet, an_ ag~rradation rate of about ~ inch per year would
resultt Thist.J woutld raise the average bed Jevel 1-foot every
25 years. The above simpiistic analysis. indicates that continued
monitoring of the sediment balance at the confluence is advisable.
Summary of Potential Post Project Morphological Changes
(a) Chulitna River will continue to expand and extend its alluvial
deposits. Decreasing the summer flow magnitude in the
Susitna River will allow the Chulitna to extend aHuviat
deposits to the east and south. This could induce erosion of
the east bankline towards the railroad.
(b) Increased deposition at the confluence will cause backwater
up the Susitna River. Lateral instability will continue after
the project.
(c) The Talkeetna River wiH maintain the ability to create its
chan net -into the Susitna system.. No consequential
interacti<'>ns can be foreseen at this time ..
r30/a 5 -14
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RM 95 to 61
Pattern
Downstream of the three-river confluenr;e 1 the Susitna continues
its braided patternr with multfple channels interlaced through a
sparsely vegetated floodplain.
The channel network consists of the main channel, usually one or
two subchannels ar1d a number of minor channels (Figure 5.20).
The. main channei is" easy to identify when viewing the river at low
flows, as its surface water width is greater than that of other
channels. Observations of cross-sections of the river fi.Qodplain
indicates that the main channel thalweg is 5 to 10 feet deeper than
in other channels. The main channel meanders irregularly through
the wide gravel floodplain and intermittently flows against the
vegetated floodplain. it has the ability to easily migrate laterally
within the active gravel floodplain, as the main channel is simply
reworking the gt'aveJ that the system previously deposited
(Figure 5.20). When the main ·channel flows against vegetated
bank Jines, erosion is retarded due to the vegetation and/or bank
mater~ a Is that are more resistant to erosion. Flow in the main
channel should persist throughout the entire year.
Subchannels are usually positioned near or· against the vegetated
floodplain and are generally on the opposite side of the floodplain
from the ma'ln channel. These channels normally bifurcate (split)
from the main channel when it crosses over to the opposite side of
the floodplain and then terminate when the main channel meanders
back across the floodplain and intercepts them. These channels
have smaller geometric dimensions than the main channel, and their
thalweg is generally about 5 feet higher. Their flow regime is
dependent on the main channel · stage. and on local behavior at the
point of b!furcation. Flow· may or may not pers!st throughout the
year.
Minor channels are considered to be those relatively shallow, wide
channels that flow over the gravel floodplains· and complete the
interlaced braided pattern. These channels are very unstable and
generally short.:.: lived.
Control
The main channel is intermittently controlled laterally where it
flows against terraces. Since the active floodplain is very wide,
the presence of terraces has little significance except for
determining the general orientation of the river system. An
exception is where the terraces constrict the river to a single
channel at the Parks Highway bridge. Subchannels are directly
dependent on main channel flow and sediment regime, and
generally react to the same •. Minor channeis react to both of the
larger channels behavior ..
r30/a 5 -15
Processes
For braided rivers that have the ability to form channel networks
within the river sediments, bankfull floods ar_e· considered to be
the dominant discharge. Floods of greater magnitude do not
significantly increase the river•s stage because-·of a. sudden
increase in flow width. Flows above bankfull stage move gravel
from bars into the channels and change the channels' shape and
network.
Dramatic. changes in channel position and form occur whenever the
river attains bankfull stage. At this stage, the active gravel
floodplain is subject to movement, with considerable local scouring
and fiiHng.-The main channel can change Its lateral location
·dramatically, intercepting the other channels at different locations
and ther.efore forcing them to readjust. Generally, it can be said
that the geometric dimensions of the main channel will remain
uniform., The minor channels react to other predominant processes
such as main channel and major subchannel movements 1 debris
accumulations and local sediment movement. When the flow
recedes 1 the channels . merely reflect the most recent governing
processes.
Through this reach of river, debris accumulations participate
heavily in forming the gravel ~loodplain and channel network.
Debris accumulations along the periphery of active gravel
floodplain bars are common~ Evidence indicates that the debris
controls several flf the minor channels and influences the
meandering patterr, of major subchannels . and the main channel~
Debris accumulatio',1S can grow, move, dissipate or emerge during
floods greater than bankfull stage, and it is impossible to predict
debris locations ar.d local river response to this process .
.
Summary of Potential Post-?_rcject Morphol.?_£;ical Chan,a~
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Under post-project conditions 1 the bankfull flood (mean
annual flood under pr·e-project conditions) could be
expected to have a recur•rence interval of once every
five to ten y~~ars. This will tend to decrease the
frequency of occurrence of both bed material movement
and of changes in braided channel shape 1 form and
network.
Over a long period, a trend towards relative stabiliz.ati.on
of the floodplain features should occur. The main
channel and major subchannels could progress to a more
uniform meandering pattern. The active gravel
floodplain may develop a vegetative cover and the minor
subchannels become relatively inactive. It must be
recognized that an extreme flood generated by either the
Chulitna River 1 Talkeetna River, or both, could mask
this process and delay observable changes for several
years.
5 ?" 16
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RM 61 to RM 42
Pattel'"n
DowL.stream of the Kashwitna River confluence, the Susitna River
branches out into multiple channels separated by islands with
established vegetation (Figures. 5.21 and 5.22). This reach of the
river has been named Delta Islands because it resembles the
distributary channel network common with large. river deltas. The
multiple channels are for·ced together by terraces just upstream of
the Desh ka River.
Through this reach 1 the very broad floodplain and channel
network can be divided into three categor'ies:
1 . Western braided channels
2. Eastern split channels
3. Intermediate meandering channels
The western braided channel network is considered to be the main
portion of this very complex river system. Although not
substantiated by river surveys, it appears to constitute the·
largest flow area and lowest thalweg elevation. The primary
morphologic parameter that has maintained the western side as the
prime conveyor of water (and probably sediment) is the fact that
the western braided channels is the shortest distance between the
point of bifurcation to the confluence of the Delta Island channels.
Therefore it has the steepest gradient and highest potential energy
for conveyance of water and sediment.
Controls
Terraces bound the very broad floodplain and only provide general
orientation of the channel network. The floodplain appears to be
filled with river deposited alluvial sediments which the river can
readily massage. Vegetation retards channel changes, but should
not be considered to control channel positions.
Processes
The basic processes described for the Sunshine Statjon reach
-would be applicable for the western braided channels. The active
gravel floodpl.aln is subject to major changes during bankfull
floods. A main channel prevails that has an irregular meandering
pattern 1 the largest channeJ geometric dimensions, and conveys
water throughout the year. ·
-----
The distributary channels branching off the western chsnnels
collect ~!eng the east valley wall and form the ea~tern split
channels.. A split channel system differs from a braided system in
r30/a 5 -17
that there is more relative stability and the channels are generally
deeper with respect to width. A better defined and more uniform
meandering pattern reduces the channel gradient, which aids in
maintaining channel stability. Distrlbution of water and sediment
from the west to east is dependent on the flow and sediment
regime of the Susitna River as well as Jocal behavior at each of the
channel bifurcation points. Quantity of sediment and ·flow
delivered eastward is expected to be highly varlab!e from year to
year.
Several intermediate channels meander through the vegetated
islands. These channels are expected to be deep with respect to
width, and have a relative gentle nradient because of the
pronounced meandering patterns... Th(., channels react to the
regime behavior of the western and eastern channels.
Upon comparing the 1951 aerial photos with 1980 aerial photos,
dramatic changes were revealed in the Delta Islands between the
Little Willow Creek and Willow Creek confluence (RM 48 to RM 52).
The western braided channels eroded away a considerable amount
of the islands and opened up a major flow connection between the
west and east.. This major change could instigate long·term
changes in the lower Delta island channel network form for several.
years. In viewing this area during late summer, 1981, it appeared
to be very unstabJej again the governing control appears to be the
steeper gradient in the western braided channels!
Summary of Potential Post-Project Morphological Changes
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The Delta Island reach is a very complex and unstable
channel network. There exists a very broad floodplain filled
w1th varying channel typ~s. Project-inducec4 ~hanges in flow
and sediment regime realized at this. reach ' be diluted by
contribution from tributarie"¢) and by the Sus .• a satisfying its
sediment tad by reworking the wide floodplain alluvial
deposits. ·' .~ic changes in the overall channel network are
...._ . .., ... ·expe· · · ·· I ;~.r.,. ·-. ...-. "'~¥ •
Local changes could occur in the main channel lateral position
but bas~c channel geometry should remain relatively similar ..
To quantify post project morphology changes with respect to
the natural system would be extremely difficult, if not
impossible.
r30/a 5 -18
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RM 42 to RM 0
Pattern
Downstream of the Delta Islands, the Susitna River gradient
decreases as it approaches the ocean. The river's basic pattern
tends toward a split channel configuration as it adjusts to the
lower energy slope. There ~e short reaches where a tendency to
braid emerges in the river pattern. Downstream of RM 20, the
river branches out into delta drstributary channels ..
Control
Terraces constrict the floodplain near the Deshka R~ver confluence
and at Susitna Station. Further downstream the terraces have
little or no influence on the river.
The Ventna River joins the Susitna at RM 28 and is a major
contributor of flow anti sediment.
Tides in the Cook 1 nlet rise above 30 feet and there1-=ore will
control the water surface profile and to some degree the sedimer~t
regime of the lower river. River elevation of 30 feet exists at
about RM 20 and corresponds to where the Susitna begins to
branch out into its delta channels.
Processes
The vegetated floodplain con·sists of alluvial deposits with surface
features revealing .old meander scrolls and filled-in channels. The
well established vegetation helps to retard erosional processes and
channel migrations, but these processes are definately on-going ..
Jn comparing 1951 and 1980 aerial photographs for the river reach
at Deshka River conf,uence ( RM 40 to RM 42) 1 there can be seen
significant channel movements, bank erosion and d~position 1 with
ban kline movement of sevei"ai hundr~d feet (Figure 5.2.3).
Several highwater c;hannels and/or sloughs branch off the mr.1n
channel into the wide floodplain. These channsls appear to be
very stable exeept for the occasion where the main channel
migrates latercHiy and intercepts one of the stems. Delivery cf
water· a1nd sediment to these subsystems is directly dependent on
the main channel flow regime and associated stage.
The Yentna River contributes about 40 percent of the mean annual
·flow to the Su$itna River as measured at Susitna station.. At the
confluence, considerable changes in bank lines have occurred since
1951 as a result of each of these systems adjusting to each other
(Figure 5.24).. Because of the variable flow and sediment
delivered by each of these systems during events, on an annual
_basis or even long-term, instability of channel morphology at the
confluence is expected to continue ..
r30/a 5 -19
At RM 19, Alexander Slough branches off the main channel
network. lt also marks the beginning of the Susitna River
distribution through the delta into Cook Inlet.. Alexander Slough
outlet has drawn attontion recently because it is the prime
navigation corridor downstr·eam to Alex-ander Creek. Comparing
ael''ial photos, there are no noticeable significant changes in the
slough outlet configuration, gravel bars or banklines" The slough
flow is directly related to the Susitna main channel flow and stage.
Because Alexander Slough is a major di~tributary that feeds
straight and direct to tidal waters, it is believed that an outlet
will naturally be maintained during normal summer flow regimes.
Summary of Potential Post-Project Morphologic~l Changes
0 Effects of the project on river morphology through this reaci1
of river would be extremely difficult or impossible to
quantify. The abov~ qualitative discussion has simply
brought out some of the natural processes and obser'lable
changes that have occurred over the last 30 years. The
dilution effect of major-and minor tributari?S as well as the
balancing of changes by the Susitna River system should
mask any me.asurabk ch~ng:s that could occur as a result of
the project for several decades.
t 30/a 5 -20
_,...,
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1-
I
••
I
••
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River Mile
RM 149 to 144
RM 144 to ·t39
RM 139 to 129.5
RM 129.5 to 119
RM 119 to 104
RM 104 to 95
RM 95 to 61
RM 61 to 42
RM 42 to 0
r30/a
T~BLE 5.1
SU.SITNA RIVER REACH DEFINJTJONS
Average
Slope
0.00195
0.00260
0.00210
0.00173.
0.00153
0.00147
0.00105
0.00073
0.00030
Predominant Channel Pattern
Single channel confined by valley walls.
Frequent bedrock control points.
Split channel confined by valley wa!i and
terraces.
Split channel confined occasionally by
terraces and vafley walls. Main channels,
side channels sloughs occupy valley bottom.
Split channel with occasional tendency to
braid. Main channel frequently flows against
west valley wall. Subchannals and sloughs
occupy ea!:!t floodplain.
Single channel frequently incised and
occasional islands.
Transition from split channel to braided.
Occasional Jy bounded by terraces. Braided
through the confluence with Chulitna and
Talkeetna Rivers.
Braided . with occasional confin~ment by
terraces.
Combined patterns: western floodplain
braided, eastern floodplain split channel.
Split channel witt: occasional tendency to
uraid. Deltaic distributary channels begin
forming at about RM 20.
5 -21
RJVER MILE 103.2
Single Channel
0
0
0
Stable
Non-erodible bartks; controlled by valley walls, bedrock or
armor layer consisting of gravel/cobbles.
Channel may be either straight or meandering i in straight
channels, thalweg often meanders across channel.
• 0 Occasional fragmentary alluvial deposits in floodplain.
, I
PREPARED BY t PREPARED FOR1
S.INGLE-cHANNEL RIVER PATTERN
FIG~ S.t
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••
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RIVER MILE 124.4
Split Channel
0
0
0
Main channel behaves similar to singJe channel at low flow.
Side channels provide flood relief at high flows (greater than
20,000 cfs),
I stands well established with vegetation.
Gravel/cobble bed material.
0 Mean annual flood ~orrelates with bankfull flow.
Channels are moderately stable.
PREPARED BY • PREPARED FOR1
SPLIT..,CHANNEL RIVER PATTERN
R&M CONSULTANTS, INC.
FIG. 5.2
i ' !
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•••
I,
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CHULITNA RIVER NEAR CONFLUENCE WITH SUSITNA RIVER
Braided · Channei
0
0
0
PREPAR.ED SY I
Floodplain is very wide and shallow even at flood flow.
Multiple and interiacing channels in unvegetated gravel
floodplain.
Move large quantities of bed material during flows greater
than bankfull.
Results from combination of high rates of bedload transportv
!ow channel stability, high sediment supply r high gradient:s
and low upstream flow t'eguJation.
PREPARED FOR 1
BRAIDED~CHANNEL RIVER PATTERN
R&M CONSULTANTS, INC.
FIG. 5.3
I
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1
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DELTA ISLANDS
Multi-Channel (Delta J stands)
0 Very broad floodplain with little lateral control.
Multiple channels consist of a mix of braided, split channel
and single channels within floodplain.
0 Relatively unstable, subject to major local changes during
single flood events ..
0 Large amount of fine suspended sediment helps stabilize
banks; dense vegetation effective in trapping sediment.
0 Bed material consists of gravel/sand with pockets of silt.
l
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PREPARED BY • PREPARED _FOR!'
MULTI-CHANNEL RIVER PATTERN
. ' . . ..
• ~ •• t , ~ • ' ...... ••
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-....1 w
> w
....1
<(
w
ClJ
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<!:
1'300
11
100
w 80
~
w > .o
CD
<(
r-70 w w u. -z
0
t-60
<t > w
..J w
5
400
300
NOTES:
t TALKEETNA a CHULITNA R \VER PROFILES-
BASED ON U.S.G.S. CONTOUR MAPS.
2. SUSITNA RIVER PROF'lL.E-BA~lEO ON tHALWEG
ELEVATtON. I
I
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80 90 100
TALt<EETNA l~lVER I
/
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CHULIT~A RIVER I
I
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l..OW£R END DEVIl. CANYON
PORTAGE CREEK
I
/ GOLD CREEK
I
/
CURRY
U.S. G.S. C H UL lT NA
GAGE SITE
SHERMAN
HO 120 1'30 140 150 ISO
PREPARED BY : RIVER M1LES PREPARED
RIVER PROFILE, SUSlTNA
RIVER AND TR 1 BUT ARIES
ABOVE SUNSHINE -26
--·-,, ..... -·----------
r.::':::;=::;;-r::-r·----"-·-----------------------------.;_--------------------, .,
m ::0::0
fY1 --r <<
0 fl'liTl :e· ::o:O
(/) ]>"'0
c: z:O z 0 c.,.
(J) -:c -lr--z ::om
1'11 _._.
tom c:c
-icn
01 )>-I ::0 -4. N -....a -Z
fT'Il> en
, -(i') c:
:tJ
1'1'1
(J1 . m
.. _,.·,.;-
:n m
~· :n m
0
CD
~ ..
500
400
300
200
100
0
.,o
:D m .,
)I
:n m
t:J .,
0 ~ ~=
-.J w > w
_J
<t
1.1.1 en
z
<t w
~
LLJ > 0
Ill
<{
.... w w
tJ... -z
0 ...
<t >
LLJ
-' w
SUSITNA-YENTNA R.
CONFLUENCE
lO 20 30 40 50 60 70
RIVER MILES
PARKS tHGHWAY
BRI OGE (SUNSHINE)
SKWENTNA. R. CONF~UENCE
80 90 100 1\0 120
'"""' --.. ;._ ~ ". ~-~
-
Looking Upstream at Portage Creek, River Mile 148.8
-
Talus Slide
PBEPARED BY: PREPARED FOF
SUSITNA RIVER
REACH RM 149 TO RM 144
R&M CONSULTANTS, INC.
FIG. 5.7
~ ---------·----------
z
0 -1-01 <( I
N > \.0 w .... w
PREPARED BY •
R&M CONSULTANTS~ INC.
----..
: ~()
SUSITNA HYDROELECTRIC PROJECT
CROSS-SECTION Number 61
~ro
~
J------<-t--------\\.o..J----~-----~-......._.----i·-----1-----.J
.. .. -~ I I : --()
.,_'Of".
~
too
1-
1-
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1
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1-
1-
P..-0
~fb~ ""'1
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~-------~---------~-· ------~--------~ : ,, 1-...
1-
1-
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1-
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~-~
p.. .. --
\ .~~
-\ /
'\ ~/ ' ~,
-\ .... --...-.. ~
~------~---t-~-~~-+------~------~·~----------------+-------·-----
CROSS-SECTION
RM 148.7
. STATION;
cP tt: ~••1111111
A
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PR.EPARED FOR:
BIR ..
. . . . ~ ' .., . . . ~ . . . . . . . . : . . . . . . . ~' . ·. . . . . . . . . . . . .• . -. . . . -. ; . . .. : -r-" -·· . : . . .
-~
tl
-
PFIEPARED BY •
R&M CONSULTANTS, INC.
Split Channel, River Mile 141.5
Gravel/Cobble Bed Material·, River Mile 140.1
PREPARED FOR
SUSITNA RIVER ~
REACH RM 144 TO RM 139 FIGo S.
9
•
--------~-----------~--------------------------------------------------------------------~------------------------------------
01
I w
1-A
z
0 --1-
<C > w
..! w
PREPARED BY •
1-
f-
1'-
1-
1-
~ 10 ~
---..... -...... "-~ .:~\ ... ,
CROSS-SECTION Number 55
1---r.~PNSmoi'J'.· Sol~ -roS.QN&:;. t .
·~--t'7~flN.S"/770# t .:s ~Na Tl:) coSBL ~s/.8ouc b£.es
I -
SRNbj ig~RV£L .
~
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~~ (j.i? ;1 rEL ---*
---· -~~-------;·-----++----r~---~~---------~----~-----, . I +-·c~ B.t..E.S ~· t;Rn.'El. G.UTH SAAib r .4TCHE.s
'
~0
'};
' • l •-• -•--•-_ _l __._
ST/J~TION
CROSS-SECTION
RM 141-.5
-... ~co88LES
oo ~o ~~~ ••••t ,..~-lliL_l___.l_l_
O: LoCIJ"riC/1 OF GRI..b-PilaTO
b 1 ,_ : t7Srn-'
!:>,;0 a-2ZO """""
b. B'l : Z &>S --. PREPARED FOR:
FIGURE 5.10 IIR ..
_::_
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Gold ~reek Railroad Bridge, River Mile 136 .. 7
_......, ________ ~ __ ,,_ _____ ····-
Gravei/Cpbble Bed MatE~rial and Sr:u·l.d Bar 1 River Mile 137.4
P~lEPARED BY t
R,&M CONSULTANTS, INC.
SUSITNA RIVER
REACH RM 1;39 TO RM 129a5
I
PREPARED FOR1
FIG~ 5.11
---------------
(J"1
) w w
P:.!EPARED BY •
z
0 ..._.
1-
~ w ... w ... '*
R&M CONSULTANTS, tNC.
"
SUSIT~,J;\ HYDROEL.ECTRIC PROJECT
CROSS-SECTION Number 41
~STATION
CROSS-SECTION
RM 134.7
~ FIGURE 5.12
-
PREPARED ~OR:
-
Curry, River Mile 120.7
-
-
-
Sloughing Banks, River Mile 124
;. __
PFIEPARED BY ' PREPARED FOR
SUSITNA RIVER [ii
REACH RM 129.5 TO RM 119 . . . MID
~-----·----~==::.: .. :_:.::::::::::~:==::::::,:.::.:.:.:.:,~==~34l·:=:=:=::::::::::::~:Gi::•:5::.1::3::::::::
R:&M CONSULTANTS, INC.
~~------------------
(.J1
I w
(.J1
z
0 -~ > w
..1 w
.. --i-
f-0
SUSITNA HYDROELECTRIC PROJECT
CROSS-SECTION Number 2 5
I
f
oo
<lf:--10£ OF [U.UFif
dot..l.bGRS NNb
co884£S
~ t'-' oo V.J 0
,. l'\1 I t I t I
oo
0 ~};_~ ._-t __ I_ I • t I I
nf;J .
..... I I I I I I I •
0 cfj ~~ I I I t I I it
PREPARED BY I
R&M CONSULTANTS. INC~ ·
STATION
CROSS-SECTION
RM 12156
• r . i
PREPARED FOR:
. ,_
. i
-_,.....
-
-
--
t'".
River Mile 104
-. -
Gravel/Cobble/Boulder Bed Material, River Mile 112.7
PREPARED BY I PREPARED FOI
R&M CONSULTANTS, INC.
SUSITNA RIVER [i
REACH RM 119 TO RM 104 . MIR
FIG. 5.15
------~------------
PilEPARED BY I
z
0 -1-
<(
> w .. w
SUSIT.NA · HYDROELECTRiC PROJECT
CROSS-SECTION Number 1 2
~§l
() ~· I & t '"' t ~ t I
STATION
CROSS-SECTION
RM,108.4
FIGURE 5.16
PREPARED FOR; .
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** -a;us .. J.S . ---GZ..JL,...
Susitna-Chulitna Confluence, Looking Downstream
\
Grave.I/Small Cobble Bed Material, River Mile 101.5
PREPARED .BY t PREPARED FOR:
· SU.SITNA RIVER
R&M CON$ULTANTSJ INC. ·ReAcH RM 1o4 To.J~M -9s . lang ..
FIG~ 5~1i~ liD
- - --; -"-- - - - -·-•:~• - - --" --
SUSITNA HYDROELECTRIC PROJECT
· CROSS-SECTION Number 7.
r..tltllsrrto,.t: t:e4(4~nY. ~
C~i!J. t.hrH SO 111 t;lfAI/iC.t. f
AF£W SHAl.4. 8-:JUI.b£~-
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7/tAJIISrrlcd: -sn#b' "'"o •
c.osetes f. ~~AV£L-
• .,_.-UPST.t'l£111-t r.,'/0 ~*' V.1tq£TR ~eN OA/ 'S(I.'INb • Mllreb W#;.~o f ~HHRTI/RE
Co"7'roNWOa.6
i • ou.. 8 ,9.1V ;e: i
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PREPARED BY •
z
0 -1-
~ w ... w
RAM CONSULTANTS, INC ..
~.
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r-··--··-1\ I ~' I • r-•
---.-.-. ---· --·----
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1
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;. .. v
STATION
CROSS-SECTION
RM, ·101.5
:FIGURE 5.18 -
PREPARED FOR;
----o----.--------;-----. --------------·
.
i
PREPARED
R&M CONSULTANTS, 1NC~
LEGEND __
---·:. Indicate a locQUon of •treambanks
and lalanda In 106.1. . .
Baatt'. pho .. o· waa tak.on In 1eao.
FOR•
1951•1980 AERIA'-· PHOTO COMPARISON.
Figure -5. 19 ~~~. · SUSITNA-CHULITNA-T ALKEETNA-CONFLUENCE~ . -
I ''
River Mile 79.5
-'
Brush Pile-up on Gravel Bar
PREPARED BY I PREPARED FOR:
R&M CONSULTANTS, INC.
SUSITNA RIVER liil
REACH RM 95 TO RM 61 ~~~~[@
FIG. 5.20 ftU [d
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PREPARED BY t
R&M CONSULTANTS,, INC ..
Delta Islands
Erosion of Sand and Gravel Bar . .
SUSITNA RIVER
REACH RM 61 TO RM 42
PREPARED FOR:
FIG~ 5.2 ·1 ' KID'
• -• : -• •• • ... • • • • •• : • • ' • ' • /. • • • , ~ .-• • f • ~ • " ·..... • '. • • ' • • • • ., ·~ ~ •• il ' • ~~ • • •• ' .,9 • .. • ' ---,,. ...
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4D+OO StJroo
• ELEVATioN.$ BAS/:0 aN AS$/.JHED Dlt'f1!M
.. St!WKFULL Et.Et/Artt:nJ IS qS.OFT.
• cRo~ SECT!CN ~~1:' QN ReCOAI/JAIS!J.A~
~IE~....~:;> .SUFn/&y' ANO R~C:../ME! 1?=/...ATION,dHIPS,
ALL ELE.~JON~ ANO STAT"IONS APPFf01fiMArtr'
•Jl.INDICATES TCP U:'E LEVEL. ONMA1?.t91 1981
~R'asS :5£C.TION LCGAT'EO 8000' CIQW/'.JSf"'l:/t:EA/VI
OF' W.tLLOW eRiiriZK&C>NFit:le:J./GE.
-
7/?tOO
-----· - -
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J . -. ... ! .... . .. ,.
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1'2.0f"OD 13(:JTOO t40t00.
· SUSITNA RIVER
..
SYNTHESIZED· CROSS
BECT!DN CEL.TA ISLANDS
~·.
Rt;;.M CONSUI.TANTS iN UATU:;}-1 1081 ......................... ~~--~ ~1.;·-·-
-~--~~-------------
LEGEND
--= L~~etlon of vegetated rlv•:tranka
and Jatanda m 1951
----= Location of sandbars In 1Q61
1951~1980· AERIAL· PHOTO COMPARISON'
SUSITNA-DE,SHKA· CONFLUENCE
Bi!a& Dhoto taken fn 18SO
Figure, 5.23' IBD
l)· . . • . • . ' . • . • " ..
1. - - - -·-- - -.. -.... - - - - - - -
PREPARED BY I
.R&M CONSULTANTS, INC ..
LEGEND
--= Location of v egetatad rlverbanka
and Iaiande tn 1951
----= Location of sandbars In 1861
Sa sa photo taken On 1 aao
1951-1980' AERIAL· P.HOTO· COMPARISON
SUSITNA-YENTNA· ·CONFLUENC.E:
... ,
Figure· 5~24'
..
PREPAReD FOR•
6 -SIDE CHANNELS AND SLOUGHS
6.1 -Present· and Proje~ted Flow Regime
Many of the side channels and sloughs between Devil Canyon and
Talkeetna are overflow channels 1 with water fiowing into the
channels only above certain flows (Figure 6.1). Several of th~
sidechannels are important as either main stem spawning grounds
or as access to spawning grounds. · Often, the sloughs have
gravel berms on the upstream end, effectively restricting open
channel flow from the Susitna River through the side channel's
until the berm is overtopped. The critical flow rate for
overtopping of the berm occurs between 15 1 000 and 20,000 cfs.
The location of the upstream end of the side channels and. sloughs
which are either blocked or partially blocked are tabulated in
Table 6. 1. For modelling in the HEC-2 water surface profile
model; it was assumed that flow into the side channels and sloughs
was restricted below 20 1 000 cfs.
Despite the fact that flow into the upstream end of the channels
was often blocked, water was still found in the side channels and
sloughs due to seepage through the riverbed gravels, backwater
effects at the lower end of the. the channel, and/or the occurrence
of springs· and small streams entering the channel. The water in
the blocked side channels is usually relatively clear, especially
when compared to the silt-laden water flowing in the main chsnnel ..
Water surface elevations were modelled from Devil Canyon to
Talkeetna, using the Corps of Engineers• HEC-2 modeL-Water~
surface elevations determined from the model studies are shown for
seiected cross .. sections in Appendix C. A complete compilation at
all cross-sections is included in the closeout report for 3.06, -
Hydraulic Studies.
The model assumes an uniform water surface elevation across any
cross-section. However, thi.s uniform water surface elevation does
not occur naturally, as demonstrated in Tables 6.2 and 6.3 by the
differing water surface elevations of different channels on a
cross-section. The disparity in water surface elevations is due to
the differing hydraulic characteristics of the channel-s, to
backwater effects, and to the inflow of springs. Consequently,
the results of the H EC-2 model should be viewed as being
somewhat uncertain In the side channels, especially at flows less
than 20,000 cfs. The most valuable data on water surface
elevations in the side channels would be actual observations at
varying stages. Even then 1 it is probable that the relationship of
the side channel stage to flow at Gold Creek w~H vary depending
on whether data are gathered on a rising or falling limb of the
hydrograph.
r31/g 6 - 1
6. 2 -Expected Changes
· Two oost-project flow options were discussed in Section 3.
Case A, the optimal power operation~ has average monthly flows at
Gold Creek varying between 5,000 -· 16,000 cfs (Table 3.5).
These flows wHl not overtop the gravel berms at the upstream end
t'f many side channels. Consequently 1 these berms should stabilize
and b€-come essentially permanent features of the system.
Howev~r, it_ is not expected thaf.; most of the sloughs will dewater 1
as water will continue to seep through the river gravels, and
there win continue to be cnflow from springs and small streams.
In channei.s where water seeps through the gravels, the water
should be clear instead of silty, especially since much of the
suspended sediment will be trapped in the reservoirs.
The flows for Case D were constrained so as to have minimal
impact .on the side channels. Consequently, average monthly flows
in the summer are such that the upstream gravel berms will
normally be overtopped, allowing water .to flow into the side
channels and having minimal impact on existing fisheries habitat.
r31/g 6 - 2
I
1
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I
)
l
I
TABLE 6.1
LOCATION OF
BLOCKED AND PARTIALLY BLOCKED SIDE CHANNELS
Blocked Side Channels
RM 100.8
RM 101.5
RM 109.0
RM 109.3
RM 114.0
RM 118.2
RM 120.0
RM 121.5.
· RM 122.5
RM 125.1
RM 127.0
RM 127.1
RM 129.3
RM 130.8
RM 132.1
RM 133.8
RM 133.9
RM 134.7
RM 134.9
RM 135.1
RM 135.3
RM 136.4
.RM 138.2
r31/g
RM 139.3
RM 140.5
RM 141.4
RM 141.5
RM 141.7
RM 141.8
RM 142.2
RM 142.3
RM 143.6
RM 144.7
RM 145.9
.Partially Blocked Side Chann~!!
6 - 3
RM 99.8
RM 100.6
RM 115.8
RM 121.6
RM 121.8
RM 123.0
RM 125.9
RM 126.1
RM 126.9
RM 129.7
RM 129.8
RM 131.6
RM 131.8
RM 132.6
RM 136.5
RM 141.0
Station
Number
LRX-4
LRX-7
LRX-16
LRX-29
LRX-31
LRX-36
LRX-39
LRX-42
LRX-43
LRX-44
LRX-47
LRX-48
LRX-52
LRX-53
LRX-54
LRX-55
TABLE 6.2
,.
~I
,I
HEC-2 SUMMARY .. SUPPLEMENTAL INFORMATION
Variation in Water Surface Elevation Between Channels I
I
I
Date of Flow
Survey (cfs)
10/4/80 9800
10/6/80 9380
10/10/80 9695
11/6/80 4950
11/18/80 2400
10/30/80 5525
10/28/80 5400
10/20/80 7230
10/17/80 7350
10/17/80 7350
10/20/80 7230
10/15/80 7440
10/14/80 7290
10/24/80 6420
10/24/80 6420
10/24/80 6420
10/23/80 6270
Water Surface Elevation (ft.)
Main Channel Side Channel{s) Comments
350.4
364.6
455.2
568.4
594.1
619~0
645.6
668.7
670.9
679.9
688.5
691.7
713.8
722o2
731.8
.• 742.6
348.2, 350.9
365.7
455.5
?
592.6, 593.7
618.5
644.7, 642.9
666.8 (slough)
667.8
673.7
680.8
689.7 (ponded)
716.3
724.0
733.5
739.9
Frazil ice accum.; · I
101 wide shore ice ..
Shore ice[ ice floes .•
Variation of 0.41 in
water surface across
main channel
Frazil ice
Ponded water in
side channel
Sm. side channel
w /flowing water
••
I
I.
I
·I
I
HEC-2 assumes a uniform water surface elevation across the entire X-sectlon.
However, this is not the case in the field, due to the complexity of the river
system. The variation in the water surface elevation is illustrated in the above
table, which shows eievation differences of up to 2. 8 feet (LRX-43) in the natural
system. Therefore, some care should be taken in assuming an absolute water ·I
surface elevation in the sloughs for a given flow.
0
r31/g 6 - 4
I
I
I
I
Station
Number
LRX-3
LRX-4
LRX-7
LRX-9
LRX-16
LRX-19
· LRX-24
LRX.-28
LRX-29
LRX-31
LRX-35
LRX-36
LRX-39
LRX-40'·
LRX-42
LRX-43
LRX-44
LRX-45
LRX-47
LRX-48
LRX-51
LRX-53
LRX-55
LRX-59
LRX-62
LRX-68
TABLE 6.3
HEC-2 SUMMARY ... SUPPLEMENTAL INFORMATION
Variation in Water Surface Elevation Between Channels
Date of Flow Water Surface Elevation (ft.)
Survey (cfs) Main Channel Side Channel(s)
8/31/81 22300 343.7(L)
8/31/81 22300 351.4(M) 351.5(L), 352.6(R)
8/31/81 22300 367. 6(L) 368.0(R)
8/31/81 22300 381.0(M)
8/31/81 22300 457.4(L) 457. 6( R) 1 455. 9(ctr. SL)
457 .3{RSL)
8/31/81 22300 489.7(M)
8/31/81 22300 523. 8(M)
8/31/81 22300 557. 7(M) 556.4(L), 557.2(R)
8/31/81 22300 572.4(R) 574.0(LSL)
8/31/81 22300 598.2(R) 594. 8(ctr. SL) 1
593.0(LSL)
8/31/81 22300 619~6(M)
9/1/81 21100 622.4(L) 621.6(R)
9/1/81 21100 648.5(R) 647 .O(L),
646.1(LSL)
9/1/81 21100 657 .4(M)
9/1/81 21100 672.2(R) 669.5(LSL)
9/1/81 21100 673.5(R) 673 .S(ctr SL) 1
.674 .. 8(LSL)
9/1/81 21100 683.8(R) 681.8(ctr SL)
682.8(L.SL)
9/1/81 21100 686.4(M)
9/1/81 21100 693. 7(M) 691.1(LSL
9/1/81 21100 695.3(R) 692. 7(LSL)
9/1/81 21100 709. 6(M)
9/1/81 21100 725.4(R) 725.1 (LSL)
9/1/81 21100 743.6@LB 743.1 (LSL) v
744.9@RB
9/1/81 21100 788.3(M)
9/1/81 21100 838.3(M)
9/1/81 21100 853.8(M)
r31/g 6 - 5
·.~
Comments
L -left channel
M ... middle channel
R -right channel
SL -slough
ponded water in
left slough
Flowing water in
left slough
PREPARED B"(i
R&M CONSUl.TANTS, INC •. -
Overflow Channel, River MHe 142.2
Bed Material, River Mile '141.5
SUSITNA RIVER
OVERFLOW CHANNELS
FIG~ 6. t
PREPARED FOR'
7 -ICE PROCESSES
7 4< 1 -Pre-Project lee Condition~
The river ice conditions observed thr.ough the wlnter of 1980-81 on
the Susitna R~ver are summarized in the report titled usubtask
3.03 -FTeld Data Collection ... Ice Observationsn prepared for Acres
American Inc. The following section is a synopsis of that report.
For more detailed information on conditions during freezeup and
breakup, readers are referred to the Ice Observation report. The
description and data in that report will provide input needed for
modeling of the ice cover development for pre-and post-project
conditions.
Very limited records are available for the Susitna River basin
relating to river ice regime, especially during the freezeup
process. Personnel from the Alaska Railroad indicated that over
the past twenty years there has been no serious flooding or ice
jamming relate.d to ice cover development on the Susitna. As a
result, they have kept no records of dates ior first occurrence of
frazil ice in the river or dates for ice cover formatton at key
locations.
However, the U.S. Geological Survey has freezeup dates for
selected sites on the Susitna River. At Gold Creek, October 15·28
is the range of dates noted for first occurrence of frazil ice. It
should be noted that this r-anga of dates indicates only first
occurrence of frazil ice at the g&ging station and may not truly
reflect the ice regime within a particular \""iver reach.
During. the winter of 1980-81, frazil ice was first observed on
October 11 in the Susitna River below Devil Canyon. From then
until early December, when the ice cover began forming 1 the
concentration and strength of ice floes varied depending on
variations in climatic conditions in the basin ..
At several locations along the river between Talkeetna and Portage
Creek,. frazil slush tended to accumulate. These location~ were
related primarily to bedrock outcrops along the banks or to con-
strictions in the channel, (both natural and those due to growth
of shore ice). Table 7.1 lists the key river sections where heavy·
frazil ice accumulations were observed during freezeup in 1980 ..
Many of these same locations were the site of ice jams during
breakup the following spring.
Though frazil slush accumulated to 100% coverage in places, the
slush blanket did not ~::onsolidate and form ice bridges. The ice
cover on the river from the Susitna-Chulitna confluence upstream
appeared to form entirely by a process ot jux.taposition4 Depending
on conditions at the leading edge of the ice cover, floes were
either carried underneath the ice cover or added to the upstream
r29/c 7 - 1
end. When velocity of flow was too high or the ratio of ice cover
thickness to water· depth too low, floes were dragged un.'Cier the ice
sheet, thus thickening the ice cover until equilibrium was reached
and upstream progression could occur. Formation of the ice cover
was initiated in the Susitna just above the confluence with the
Chulitna River. No severe changes in water levet were observed
during the formation· process. On the average 1 . water level rose 2
to 4 feet during ice cover formation. Howeve~, as the leading
edge of the ice cover progressed upstream through certain
reaches, levels rose enough to. cause water to begin spilfing into
side channels which were previously dry-or had formed an ice
cover prior to freezeup in the main channel. Listed below are
locations of the primary side channels carrying overflow due to
rising water Jevels as the ice cover developed from the confluence
to Gold Creek.
0
0
0
0
0
0
0 .
West channel between RM 112 & 113
East side channels between R&M ·!13.8 & 114.8
Far west channel below Curry between RM 119.2 & 120.4
Far east channel between RM 121.1 & 122.3
Slough on the east side of the floodplain between
RM 122.4 & 123.0
East channels near Skull Creek confluence between
RM 124.4 & 125.9
East channel between RM 132.5 & 133.4
Complete ice cover development from the Susitna-Chulitna con-
fluence to Devil Canyon took approximately two weeks during 1980.
By the end of February, the average river ice thickness at Gold
Creek was 2.9 feet, very close to the historical average for that
site.
Overall, there were no observable changes in river channel con-
figuration due to ice cover formation. Water levels were low
enough that less resistant alluvial· banks and vegatation on the
banks and mid-channel islands were not adversely affected by
movemen~ of ice floes in the channel or development of the ice
cover. For the most part1 flow was confined within the armored
portion of the river bed.
However, in the spring, ice jams and general breakup of the ice
cover had a more noticeable effect on river banks and vegetation.
Location of ice jams observed during the May of 1981 are listed in
r29/c 7 -2
Table 7. 2. Comparison of this table with Table 7.1 wil I verify that
ice jams occurred in many of the same locations where accumulation
of frazi1 ice was observed durin~ freezeup.
As described in Table 7. 2, the most significant changes in banks
and vegetation occurred from the Susitna·ChuJitna confluence
upstream to RM 101.5. Several new ice scars in the vicinity of
Whiskers Creek confluence and new bank erosion were observed
after the ice released.
7.2 -Post-Project lee Conditions
lea growth simulation studies conducted by Acres American, !nc.,
are summarized in the report titled 11 Subtask 3. 06 -Hydraulic and
Ice Studies 11 • The ice simulation studies, using reservoir water
temperatures f:-om other studies, river hydraulic conditions
determined from the HEC-2 Water Surface Profile studies and
varying clirrlatic conditions, have determined that once both dams
are built, water temperatures downstream of Devil Canyon will not
drop to 32°F . until approximately 15 kilometers above the
Susitna-Chulitna confluence. Even though the water temperature
drops to 32°F, ice cover formation will be insignificant above
Talkeetna unqer post-project conditions. Under pre""project
conditions, the Susitna River contributes 70-80% of the frazH ice,
appearing at the Chulitna-Susitna confluence, with most of the
frazil ice being formed in the Devil Canyon reach. This frazil Tee
generation will be essentially eliminated once Devil Canyon Dam is
constructed, greatly diminishing the ice delivered to the lower
Susitna River. This is likely to delay ice cover formation on the
lower river 1 although this effect can not be quantified at this
time. ·
Under post-project conditions, ice prrJcesses should not play any
significant role in the shaping of the river morphology above
Talkeetna. Little or no ice cover should form in the main stem
above the Chulitna-Susitna conf.luence. No ice jamming should
occur in this reach, since little ice cover will form in it. The ice
run from the up;:>er river will be trapped in the reservoirs.
Little data are available for ice conditions below Talkeetna ..
Post-project winter water levels will be 1 to 2 feet higher than
pre-project levels, due to winter power releases 6,000 to 8,000 cfs ..
greater than pre-project levels. However 1 the lower river has
such a broad floodplain that, should staging or ice jams occur,
there ~are several flow relief channels. Consequently r ice
processes have some influence on channel processes in that they
may redirect the main flow, but do not affect the overall pattern
of the river.
r29/c 7 - 3
TABLE 7.1
LOCATION OF ICE ACCUMULATIONS
DURING FREEZEUP -1980
Location
RM 1 OS . 3 - 1 05. 6
between LRX 10 & 11
RM 110.3-110.4 near LRX-13
RM 111.5 -near LRX-14
RM 121 -just above Curry
RM 122.6
RM 123.3-123.7 near LRX-27
rock.
RM 126.0-126.5 -near LRX-29
RM 128.5 -near LRX-31
RM 131 -just above Sherman
RM 135.7 -near LRX-43
r29/c
Description
Return to single channel from spHt
channel with turbulent flow.
Local change in gradient.
Multiple channels join to form single
channel at Curry. Rock wall on right
bank. Shore ice growth from the left
bank constricting the channel.
Channel constricting, right bank bed-
rock.
Channel constricting., right bank bed-
Channel constriction to single channel,
prominent bedrock outcrop on the right
bank at RM 126.5.
.
Prominent bedrock point on right bank,
wide shore ic'e on left bank constricting
the channel. ·
Split. channels join to form single
channel at Sherman. · Channel
constricted by shore ice _growth.
Prominent rock point on the right bank.
7 - 4
TABLE 7.2
ICE JAM LOCATIONS DURING BREAKUP
MAY I 1981
Location Description
Susitna-Chulitna to LRX-7 (RM 101.5)
RM 112.6 to 113.4
RM 115.1 to 115.5
0
RM 119 .. 1 to 119.9
RM 120.8 to 121.0
RM 126.0 to 127.0
r29/c
Largest ice jam observed during
breakup. Water and ice observed well
up into vegetation on both sides of the
floodplain. New ice scars on trees on
mid-channel islands net LRX-7 after
release of ice jam. Increased bank scour
above LRX-3 and in the vicinity of
LRX-8 along the left bank.
Key of the jam near LRX-17 extending
upstream through single channel to Lane
Creek confluence, Heavy overflow into
below LRX-17. No new ice scars or
signs of bank scour apparent af'ter
relaase of the jam.
Ice jam initiated by rock point on the
right bank. Heavy overflow through
channel between the islands at RM 115.3 ..
Ice jams of var·ying magnitude occur
nearly every year through this reach.
Overflow in all side channels to the west
of the main channel. No signs of bank
scour or e·ffects on vegatation after
release of the jam.
Small ice jam formed above Curry \Vhere
mulitple channels join. Channel c-onfined
by bedrock wall on the right bank and
Deadhorse Creek floodplain deposits on
the left bank.
Ice jam through the constricted reach at
LRX-29. Bedrock outcrops along right
bank hindered ice movement. Overflow
in far east channel beginning at
RM 126.7.
7 -5
Location
RM 129.6 to 130~5
RM 135.7 to 136.1
RM 139.0 to 139.8
RM 142.1 to 143.1
r29/c
Descript!,...;.o.;...n ____ ~ __
Ice Jam caused by local breaks fn
gradients near LRX-32. Bedrock walls
and outcrops in the channel bed may
have influenced formation of the jam.
Little. change in water level upstream 1
due to overflow relief in east channel
below Sherman.
Jam initiated by rock outcrop on the
right bank at LRX-43.. Overflow in side
channel at LRX-44.
Jam in the main channel above prominent
rock point on the left bank. Overflow
through the east channel.
Ice jam initiated at channel constriction.
7 - 6
BlBLJOGRAPHY
1. Alaska, Uni_versity, Arctic Environmental 1nformation and Data
Center. 1974. Alaska regional profiles; southcentral region.
Alaska Office of the Governor Juneau, AK. 253 pp.
2.. Baxter, R.M. and Glaude, P. 1980. Environmental Effects of
Dams of Impoundments in Canada, Experience and Prospects.
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3. Blench 1 T. 1969. Mobile-Bed Fluviology. University of
Alberta Press, Edmonton, Alberta.
4. Bray, D.l. 1972. Generalized Regime-Type Analysis of
. .-~!berta Rivers. Ph. D., Thesis, presented to the University
of Alberta, Edmonton, Canada, 232 p.
5. Brune, G.M. 1953. Trap Efficiency of Reservoirs.. Trans~
Am. Geophys. Union, June. U.S. Dept. Agr. Misc. Publ.
970, p. 884 ..
6. Church, M.A. 1972. Baffin Island sandurs. A study of
arctic fluvial processes. Geological Survey Canada Bulletin
216, Information Canada, Ottawa, 208 p.
7. Dolan, R.1 Howard, A. and Gallenson 1 A. 1974. Man's
Impact on the Colorado River in the Grand Canyon, American
Scientist 1 62( 4), pp. 392-401 .
8. Everts, C.H. 1976. Sediment discharge by glacier-fed rivers'i
in Alaska. Pages 907-923 in Rivers '76. VoL 2, Symposium
of Inland Waterways for Navigation, Flood Control and Water
t:~versions. 3rd Ahnual Symposium, Colorado State
University, Fort Collins, Colorado. Waterways, Harbors and
Coastal Engineering Div., American Society of Civi.l
Engineers 1 New York, NY.
9. Fahnestock, R.K. 1963. Morphology and hydrology of a
glacial stream, U.S. Geol. Surv. Prof. Paper 422-A.
10. Fortier, S. and Scobey, F.C. 1926~ Permissible canal
velocities, Trans. ASCE. Vol. 89, pp. 940-956.
11. Freethey, G. W. and Scully, D, R. 1980.
the Cool< Inlet Basin, Alaska, U.S.
HA-620, 4 sheets.
Water Resources of
Geol. Surv. , Atlas
12. Gottschalk, L.C. 1964. Reservoir Sedimentation, in Chow,
V.T. (Ed.) Handbook of Applied Hydrology. McGraw-HHI,
New York.
r29/d - 1 -
13. Guymon, G. L. 1974. Regional sediment yield analysis of
Alaskan streams 1 ASCE Proc., VoL 100, n .. HY1, p. 41-51.
14. Henderson, F.M. 1966. Open channel flow, MacMillan, New
York, 522 p.
15. Kellerhals, R. and Bray, D. I.
for coarse fluvial sediments,
August.
1971. Sampling procedures
J. Hydraulics Div., ASCE,
16. Kellerhals 1 R., Church, M., and Davies, L.B. 1977.
Morphological Effects of lnterbasin River Diversions, in Third
National" Hydroelectrical Conference, Quebec 1 30 ... 31, May 1977,
Canadian Society for Civil Engineering, pp. 833-851.
17. KeHerhals, R. and Gill, D. 1973o Observed and Potential
Downstream Effects of Large Storage Projects in Norhtern
Canada. Proceedings 1 11th International Congress on Large
Dams Mad rid 1 pp. 731-754. ·
18. King, N.J. 1961. An ExampJe of Channel Aggradation
Induced by Flood Control,. U.S. Geological . Survey Prof.
Papers 4248 1 15, pp. 29-32.
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Proceedings, Institute of Civil Engineers, England.
20. Lane, E. W. 1955. The importance of fluvial morphology in
hydraulic engineering: Am. Soc. Civil Eng. Proc., v. 81,
No. 745, 17 pp ..
21. Leopold, L.B. and Maddock, Thomas Jr. 1953. The
hydraulic geometry of stream channels and some physiographic
implications: U .5. Geol. Surv. Prof. Paper 242, 57 pp.
22.. Leopold, L.B. and Wolman, M.G. 1957. River channel
patterns: braided, meandering and straight, U.S. Geol.
Surv. Prof. Paper 282-B.
23. Leopold, L.B., Wolman M~G. and Miller, J .. P. 1964. Fluvial
processes in geomorphology. W. H. Freeman and Company,
San Francisco, 522 pp.
24. Mackin, J.H. 1948. Concept of the graded river. Geological
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25. Mallard, J.D. 1973. Airphoto interpretation of fluvial
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Thorn Press Limited 1 Ottawa, Canada, 38 p.
r29/d - 2 ..
26.
·27.
Moore, C . M. 1969.
Flow, In Moore1 C.M.
Watershed Changes on
Austin, PP~ 101-117.
Effects of Small Structures on Peak
and Morgan, C ~ W. ( Eds ~ ) , Effects of
Streamflow 1 University Texas Press,
Neill, C. R.. 1968. A re-Examination of Beginning of
Hydro. Res. Movement for Coarse Granular Bed Materials-
Stn., Wallingtord1 England, Internal Repor~ ...
28. Neill, C.R. 1981. Letter Review of Susitna River
Morphology Studies 1 December 16.
29. Neill, C. R. 1967. Mean velocity criterion for scour of coarse
uniform bed material, IAHR_, 12th Congress, Fort CoJlins,
Colorado.
30. 0strem, G. 1975. Sediment transport in glacial meftwater
streams. Pages 101-122 in A. V. Jopling and B.C. McDonald,
eds... Glaciofluvial and glaciolacustrine sedimentation. Society
of Economic Paleontologist~ and Mineralogists, Tulsa 1
Oklahoma, Special Publication· ::..!_j.
31. Petts, G. E. 1977. Channel Response to Flow ReguJation: the
Case of tb.e Rivet\ Derwent, Derbyshire, in Gregory, K.J,
(Ed.), River Channel Changes 1 John Wiley & Sons, New
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32 .. Pharo, C.H~ and Carmack, E.D. 1979. Sedimentation
Processes in a Short Residence-Time Intermontane Lake!'
Kamloops Lake, British Columbia. Sedimentology ..
26:523-541.
33. R&M Consultants, Inc. 1981a. Susitna Hydroelectric Project,
Subtask 3. 03 -Field Data Collection -Jce Observations,
prepared for Acres American ln~orporated and Alaska Power
Authority, August.
34. R&M Consultants, Inc. 1981b. Susitna Hydroelectric Project,
Appendix B. 4, Regional Flood Studies, prepared for Acres
American Incorporated and Alaska Power Authority,
December.
35. R&M Consultants, Inc. 1982. Susitna Hydroelectric Project1
AppendiX 8.8, Reservoir Sedimentation prepared for Acres
American Incorporated and Alaska Power Authority, January.
36. Santos Cayudo, J., and Simons, D. B. 1972. River
response, Chap. 1 in H.W. Shen, ed., Environmental impacts
on rivers, Water Resources Publ., Fort Collins, Colorado.
r29/d - 3 -
37.. Schumm, p .. A. 1971. Fluvial. geomor\pitoiogy -the historic-a!
perspective, fn Chap. 4, VoL lf rLW .. Shen, ed., River
mechanics, Water .Resources Pub I. 1 For·t Collins 1 Colorado ..
38. Shulits, s. 1934. Experience with Bed Degradation below
Dams on European Rivers, Engineering News Rec .. 1 June,
pp. 838-839.
39. Simons, O.B. and Senturk, F. 1977. Sediment transport
technology 1 Water Resources Publications, Fort Collins 1
Colorado, p. 465 ..
40. Stabler, H. 1925. Does Desilting Affect Cutting Power of
Stream? Engineering News Record, December 95, 24 1 p. 960.
41. Stanley, J. W. 1951. Retrogression of the Lower Colorado
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Stanley, Transactions, American · Scclety of Civil Engineers,
Vol. 116, Paper No. 2453. ...
42. Stevens, M.A. and Simons, D .. B. 1971. Stability analysk:
for coarse granular material on slopes, Chap. A in H .W ..
Shen, ed., River Hydraulics, Vol. 1, Fort Collins, Colorado .
43. Taylor, K.V. 1978. Erosion Downstream of Dams., .. 1n
Environmental Effects of Large Dams, Report by the
Committee on Environmental Effects of the United States
Committee on Large Dams, American Society of Civil
Engineers, New York, New York, pp .. 165-186.
44. Trihey, E. W. 1981. Utilization of Time Series Streamflow
Data in the Determination of Project Effects on Physical
Habitat for Spawning and· Incubating Pink Salmon.. Presented
at the Western Division of the American Fisheries Society
Symposium, Acquisition and Utilization of Aquatic Habitat
1 nventory I nformatioi1, October 28-30 1 Portland, Oregon •.
45. Tutt, D.B. 1979. Kootenay River Diversion Project River
Regime and Morphology Studies, in Fourth N~tional
Hydroelectrical Conference, River Basin Management,
Vancouver, B.C., May 7-8, 1979 1 Canadian Soci~ty forCivil
Engineering, pp. 530-554.
46. U.S. Army Corps of Engineers, Alaska District . 1975.
Hydroelectric power development, upper· Susitna River basint
southcentral railbelt area, Alaska. Draft environmental impact
statement. Anchorage, A K. 998 pp.
47. Woodward-Clyde Consultants. 1980. Interim report on
seismic studies for Susitna hydroelectric project.
Subtasks 4.01 through 4.08. Acres American Jnc., Buffalo,
NY. Report for Alaska Power Authority. 1 Vol.
r29/d - 4 ...
48.. Ziegler 1 T. 1973o Material Transportundersokelser i norske
bre-elver 1971 ~ Rept. No. 41/73, Hydrologisk avdeling,
Norges, vassdrags -og elecktrisitetsvesen, 91 p. (English
summary).
r29/d - 5 -
r29/g1
APPENDIX A
SUSITNA RIVER STAGE-DISCHARGE
RATING CURVES AND TABLES
----------. ----.. - - ----- -.. -------. ..
J
0
' -
.L.
5_.;..
40
!'I -
30. n~';.
f•
• :i
±LU· .·
~Q JJ.Jtlll 1
,;.
<I
'·:--1
'J
~ if ~
g_.
A
,---·
7 ,;:r--..,: 6_ II 1.\. -~
1-
:I: m (!) 4 -liJ
:I:
' '-'-r w 3-(!)
<t I ~!) ;...._~ ~
2
• .
i<' ~
4 i CorJi~ :--; I I I X 103 3 X l04 ~ I ~--~~--J -~.-~t) l X ~:1"-2 :) ~ 5 6 7 8 9 j+ 5 i " 8 ~ .;; 4
~'
PREPARED -BY"r 0 I S·CHARGE JC.F.S.) -. •ARED FOR;
~· •l--2]~~; %~ ~·.-~ ~~-_-~ -·
~ -L ;:tb ;:.-: -RATING CURVE FOR SUSITNA RIVER AT GOLD CREEK" mm R~M CONSULTANTS. I.NC.
.
·-,' .· . ' FIGc~ ,. -: -· REDRAWN FROM U.S.G-~S. DiSCHARGE TABLE No.10 . -. :: ..
-
;~~h Diacharge :a,& l
;r ru
.10 -······--\
/ (··. .20 -~!,_.;_ __
/{ )' .·~ ----------
~~:-40 -----·
.60
.70 .lE!.::....w
Differ·
cnce
Cft
---
-·------
.... ___ _
-----··
r------
r-------
Gage Discharge
height
DitTer·
cnce
-··-----57~5'0 .~0 ----------· -~~
.60 ---~-Qf:??.. .. .E..QQ
• 70 ---:~: ···l----
.80 ••• I.Q.Q •• .r.. ···-·--·
.90 ---~9.9.9. . ..S.Q.Q
.. INTERIOR aJ -sll DE"'ME~~~f -. -----$tq. No. L.$ §:Z.g:Q_ Q Q GP.Ol.OGlCAL SURVEY (WAlEil RESOURC:~S DIVISlON)
G.age D' h height m: arge Differ·
Fttl • C/1 Cft
7.00 ,_ __ zgg_Q ~oo __ ..;;,c __ ;._
.10 !· •• zs. __ gg [
·-:--· ----
.20 ___ zaQQ -----.----
.30 :----8LQQ . ..3..QQ
8400 . ,40 r---·--------<!2:5'0 .W.· ••• .:.
,,0 ••• 87.S.Q f
.60 ,_ ... ::ZL9..9. --------
---------.
.70 ••• 25..~ ~L"'J"')
• ...::t.~Y--
;80 i----9.ft92 400
---------.90 ,_.10.6-.ef . ---.....
s .oo r.:Lakr29.
.2o .Lt..4.£t?.. , ---· ----
.~0 _ILEQQ. ..... --
• .co 1Z..g._<;?9_
r------~-
,,0 !..:?.:.t?..r:JP.i,_4r;_Q.
.60 ,_l:?..f!:?..Q .SaQ
.1o ,_L~.G..t2e ~.J .....
.so _lfltJf?.r2. t ", ~------flO
.90 r-.L4li..9..t?.. t;oo
--~----
Table No. L Q
Dischar~>e l D.· iifcr· G~:~ge o· h miTer· Gage Disch~.rge Differ· . G~ge Discbzr•e Oiffer-
o cnce height &sc arge ence height ~nee hcaght · .. cnce
'
Cft Cft Fttl Cft Cft h Fttt Cft Cft Fm Cfi C[i
L5.QQQ -~£!9. //.oo .G..ZClP.Q ,..aaa l,iJ.D!l ~£.~ .f.LQQ t5.oo ,.WEf:E2 ...1..2'29
~to .!..$.5QQ. -··t··· .to _gz?._gg_ .to ,...d.!fiLO ... Q .to G..9Ef?Q ~------r--.------~ ......
.2o .1/i?..Q.QQ .~o 2.,fj.f~~ .2o _1./e.?J22 .20 :Z/2.~
.~o ..L.~!?..f?e ---·--.3o :Z2.4..C:XZ ------.~o :-4. 7.-2?-£ -----.~ 7L.9..~Q ----.
Ao .. L7QQQ ~5;.~ Ao 9J?.?.QQ. ~~~ =~~ . .4o r.#._BgCQ -.~ ~-gQQ ~~0@
.so .t..ZS:.Qf?.. _6_QQ ,,o ~.l .. QO{?_ ··--·--.so 49.?..90 ·'~ :Z4.S.C?R .L:£@
.60 .I.!JL~Q .60 .3..l .. ~-.60 r-S:Q..~QQ. .6o 'r2.1PJ29.!.2.
r----·-·-··-----....... --· ----~~
.70 .t.E/.7Q..Q .70 .E,~_tf!f!?~ .70 r--:5''7-9.£ .70 ~-7..~~
.so ./.2.EJ;).2 ··-··-.so 3.3d..QQ-----.so _f?Z_~ ··1·--.so ::I.9..~ ---
~--·---.. .~....... ~------.-.,.. .....
• 90 .1.29..c;Q. ------· .90 a..4i?.~ .f?O.t2. .90 ~fi.~:Z.C?fi .liP.!?~ .90 8.Q!iff: -~-----
/().00 _ZQf?...qQ __ __ tz. .oo ..2.5QQ?.. _:J_r;g 14 .oo ,...£$..Qr:!2 .L~J?..r2 '"' .oo az.~ __ _
.to _gL/..9!?.. .to 3..5..9.Qf?. .to 5..??:3..C?f2. .to a~_!2QQ
--~ ·-· -------~--·· ----....--.
.20 .Z.LZQQ .2o 3..~_8_QQ .2o S..ZG..QQ ·.20 B.$.QCO ---· .. --~ -------------~
.3o .2.Z3f?Q .3o :2.ZZQQ .3o r..S.:l?..9..P.Q .3o ,_8.~§:e2
···--·------fill!•------.................
.40 2..~.9-QQ _~_.,,I'Y"')__ .~ .:fl..~_€f22. .4o G..a.?-c::Q
~~ ----··------·-,40 f2_8_Q.Qf ---
.)0 .?..55.!22. "7oo .,o . 3..9.5..C!Q .so ~-~L~ee
.60 .?.4.:?:.QQ --t..:::+---.60 l-i<l4.eP----. ·-.60 ~-~g~-~ ---:--.60 -----______ .. _
.10 2:.4.9.00.. •• _,_ .10 .4..LE.e.e. .... -~--.10 L~A.Loe -_-_--_-__ -_ .10 ~------~--.. ---
... ···-4 ·-------I ......... __ _
.80 g_€.€9.9-. .so ___ ggt?..f:_ .so rR..f?.4 0.2 .80 1------
•• 9o _gkS.9.f ;.c?2 .90 .4-§..t.t?.t?.. ~~ f!;;_ .90 r.<eJ:Z0.2t~ .90 r.----------~~~~=~
.50 89..S:~
This table is. applicable for open-channel conditions. It is based on /.4: discharge measurements made duri~g __ /._2~.2 .. ::L2.Z:g ____ _
--~---···········--·····-··-······--··· .. -·-····-~---------··--·---and is·------------··---weU defined betv.•een •• ~9..?.J2 .... cfs and .(!2.S,Q9Q ••. cfs. Camp. by A.f!f. D date ~:3.:..??
?.?:.:: ... c-?..~~~_s~ .. l'Y.f.~ .. C..c:?.,P..CP..f!.J!r;_.;:t:C__fr-e.a::t.-f-~.6~fi-.L~(;O.rc:t:. ••• <:fq.cf..'q;!. .•. p.~cL!2.e:..L2~.Z.::LEzg.__.._.
~--"l;:l.:..:. .... oc-9.t.:ac.t: .. l.:;: __ /.(!?_:::;!:.. _____________________ : ________ ··~----.. --···-······----···-··-·--·---------------··-----·--·---:··------
•
Ckd. by ........... _date."' •••• ., ...... .
U.S, GO\fUNM(IIJ PIINflii.G Otrl<t . lU1 Of-UI•UI
-
...
-
... . • ~.\ .. .J"q•\ •.•.• ', .. ~· .-•. .
9-210
(Rev,l-67} UNITED STATES DEPARTMEN'r OF THE ~NTERIOR
GEOLOGICAL SUJVEY (WATER RESOURC!!S DIVISJON}
l<ttti~t~ ttti1/e ~,. -----------------------------------------------------------~------~-~--~----------------------------------------------------------------------·
Table Ne • .Q 1..
Begin ------....~----Ylt. MO. Hill.
jrfJm ·------------------------to -------------------------------J frorrt -------------------------to-------------------------------, . frmn -----------------------·-to _____________________ ,....... ____________ _
Gage D' h height tsc arge
Fttl Cft
:9'1100 .20 "'S&./.k --~--
.3o t.?:.Z.!~a
~ "":'~{) ~Do .40 _-,! __ ,_~----
.~0 l3J.J-2t.:cP..
.60 iJ 33. .. :JP-Q
1/7 d ·--.10 ""'-\lr./.wa
.10 -----------··
.20 ------------
.40 ~---.. ------.. --
.so
.60 !------------
Differ·
ence
Cfs
I
!
____ ,. __ _
----~~·--
--------..
--------·
--------·
--------·
Gage
height
Fttt
.oo
.10
.20
.3()
.40
.50
.60
.70
.so
.90
.00
.10
.20
.~0
.4o
Discharge
Cft
-------~--.....
Differ·
ence
. Cft
Gage o· h hright asc arge
Fttl Cft
.oo 1------------
.10 !------------
.20 !------------
Differ-
enc~
Cfs
---------
---~-----
-~~----~~
.3o ~--~---------_____ ... __ JI
.40 f------------
---------
.60 f------------
---------
.70 1------------
.so !------------
---------
.90 f------------
,10 1-••••••••-•w
---------
.20 f------------
.30 f------------
--~------
.40 1--------------------·
.~0 1------------
.60 f--------------------·
Gage
height
Fttt
.00
.10
.2()
.30
.40
.50
.CiO
.70
.80
.90
.00
.10
.20
.~0
.40
.60
Discharge
Cfs
Differ-
ence
Cfs
_. ______ _
---··---
------------1
r--------
-·---··-----'t
Ga8e . heigh~ Dtscharg~
Fttt Cft
.00 -----..1..-----
.10 ------------
.20
.40
Q_ .... _____ .,. __ _
.60
________ ,... __ _
.10
.80
.90 ........ ---~~---
.00
.10
.20
.30
.~o ------------
.60
Differ-
ence
Cfs
------"""-
--------
--------
f--------
Gage
height
Fttt
Discharge
Cji
.oo ~----~------·-
.10 !------------
.20 1------------
.30 f-*·--------
.40 !------------
.~o !------------
.60 1-----------
.70 1------------
.80 !------------
.90 ~----------
.oo f------------
.10 1------------
.20 ·f------------
.30 ~-------------
,40 1------------
.so r------------
.60 !--~---------
Dttf"er-
ertce
Cfi
-------
--------
---------
---------
---------
---------
---"'-----
Gage 0 . _:......._
height ts.....u.a.;ge
Fttl <t.fr;
.20 r--~""-----:--
.30 ___ ., __
Ao r--... ------
~----.~--....
.90
.10 r---~-------
.~0
Ao
.50
.CiO r.. .... ..., .... _____ _
Ditfer·
ence
Cfs
--------;
I
--------~
.70 f--------------------· ,;o ----.-r·--•-"1!'• .70 1------------· .70 1-----~------l .10 .70
.70 f-·-----------------------.so .80 -------·-·--.so .so .so .so .so r-----·-----
.90 ------------.90 .90 f-·------------~-----
.90 .90 -·-----------.90 ---~----------·--·--~
This table is applicable for open-channel conditions. It is based on ----discharge measurements made during----------------------------------
--.. --."·-------·-------------------------------------------------------and is---------------------well defined betv.·een ···-----------cfs and ----------·-----· cfs. Camp. by----~·-date·--·--·---
-----~--"~-------------~-~------~----------~------~--------------------~--------------------------------------·--------------------------------------~--------·-----4·-· -------------·------------------Ckd. by ............. _.date---------·
-JIUtiU-~!OQf'-'7oP--
-..
---.. -------au ---- ---'
~
'
: .
s __ ~.
4--
30-
20
,.,..
v . '
-"""
IO I
Q
A -o-: 7_ 1.1..
~
1-s
::r i (.!) ~' I -!JJ i :z:
4
w
c;.t
<(
3 (!)
2
•
I
' f . 9 l X 103 3
I
B ~ I X I 0 4 : 5 . 5 7 :l X 105 . :t 5 f: 7 a 4 5 6 7 .: j ... -·--·=> ? -·
PREPARED BY• 0 I SC HARGE (CF.S.) PREPARED FOR•
l>l~J ~~~~.~ RIVER AT SUNSHINE B~fl ~ I-~7:,.' _· RATING CURVE FOR SUSITNA . R&M CONSUlTANTS, INC.
A .. 2 . ' . FIG~ I
nr-,...n/1\ •U I""MI"''~ I I f" I"> .,... -""Tf'.j'•t..fl\_~f">C". ·T_I\.01 r-.. ·,...r . Ll·
.. . ••
------·------· ----
9-ltO
(Rev. 2-67)
Gage Disch;uge height
Fnt C[s
• 00 .,.., _________ _
.20
• 30
.40 ~-----------
.~o -----------
.60 ..... ~--------
.70 ... __________ _
Differ·
ence
Cft
---------
... --·---~
.80 ~-----------
--------·
• 90 1-------------
.oo ··---------
• 10 1-------------
.20 1------------
.~0 -----------
.40 1-------.. ----·
.~o
____ ., _____ _
• 60 -----------·
.80 -----------
-~-----·
.9\} -----~~-----
Gage
h~ight Discharge
Fttt Cfs
3 .oo ••. 1k.4:~1
• .to (_9:_.f_Q_Q
/(' . .2o ---~~-~-a-
Differ·
c:nce
Cfi
.30 l/.~.1-"'--:J. I. ;
t.t •• :L.
.4o .L.7..t.::.?..
.60
.70 ·.;...·. ·-c,.c, -•-tt-------
_ .. I lc...~ <.~ .so ' ..... ~-------
----:--··i
----\.---
1
-·------
UNITED STATES DEPARTMENT OF THE INT~RIOR
GEOLOGICAL SURVEY (WATE~ RESOURCES DlVISION)
Gage
height Discharge
Fttt Cfi
Differ·
ence
Cfi
. , ,
-----~!: •
---------
30 .... (1 t 00 j • 1-.::z .. ..::.. ........
.,. __ J:z:::,OOT
---··----
--------~
# .I "" .1o ~-~~a..c~ . ...:. ... :i.;._
'2. 00 .80 .:... ·-v.i"------
---------
Gage
height
Fttt
Discharge
Cfs
..
.;o .;_.,:_,!.~:~? .
"(.., 'j ·""' .40 t ..... .;:, ___ _
Differ·
encc
Cft
.,. ______ _
Gage D' h height ISC atge
f·ut Cft
"9 ") . oo ~;&:z.Q?.: •
.. ,(""'/. 1),-, r'l .'to :v. • .... ~-'"--
.60 • / !{..(.. ~-..t-~------
.so
Differ·
ence
Cfi
... _____ ,.it
-----·-,..
___ ,. ___ ..,
;.....91 c:lO·.::>
.90 ~--·--!:·-----:Js zo" . .90 ---"--------.90 ~-1 .. 1~_y__ lit. i
\ ---------
~ l ...,,c.) • 70 Fo:--_:c; ___ ... _
.50 ::~) ·:to· ---..t--------
6() ""'! ()r.c .
. G'-J----~---.,.-,., 0 ·J .1o .! ........ e .... ·--.-----
' I r; . ~~; I o.oo t-... ~_.v;_,._ .. _
• 'l' J. .-.. .10 .P.. ... _ .... _..:=::.
20 1/,.,,-:.:., 7..'C•O . ~~~·-------
--------
Gage
height Discharge
Fttt Cft
1/.oo .ZZ.CU?P-•
., I:J ") ,.· v
.20 '-"'..:r.o..h..:" ---
at :.)o/· .90 ... V-.. :~ • .J.; __ v.,
? .::. ~ rtr." I c.. .oo 1-"-Cl..J..r~.~il
.10 'rf;1 .. .J..?..r:._
This table is applicable for open-channel conditions. It is based on r-discharge measurements made during __ /..f_rJL~-~-.---------.-----------
"··---.. ·-----------------. ----------------------7. ----~-----------------and is ---.t::t.JLC:..S.If-----weH defined between L9.;_C..t.1k ___ cfs and __ l:,:--!..~-J;'..:.... ••. <:f'f.. /' ··. /. (i .
............. Q..:=: .• Lzg .. ~ __ \.....!$...:..Ql ____________________________________________ ~---,----------------~--..,-----.... ·o--------"'-------------------------------------·
--··---.. ··---... _,. ..... _ ... ..,,.. .... ,.,.,.,. _____ ~ _____ ,. ____ ..., __ ... ___________ ..,.. _____ .,._lot_ .. ___ , ___ ""'~"'""~----·""'--··-... ----------..... -·--'!01! ___ ., __ ..
St 1.1 /C' ,., ... ,... a. 110. _ ~ .k.o. . ..;,.:. ,.,;;;:. ,:;:_ ~a.
Table No. :'/
Differ-
ence
C/s
... ~-------
··-·-----
---------
---------
--------·
--------·
--
Gage:
height
Fttt ff$
.... .j), ... ,--.5o IL .. :,-t ..... !..;!.::..
.so
~ Differ• J ence
Cft
----""----
. -.. ~ ... ·~ ------·--
---------...
~--------
-------------------
5 __
30_
IQ_
9_
a_ -7_ ...,:
u.. -6_
r-
:X: 5_
(!) -UJ :r: 4_
w
(!)
<t 3_ (!)
l X 103
PREPARED . BYi .
I
2
ll-i-H11mtt1 ttf
.
. .
.
t 1 lt!l 4 I I
5 6 7 8 9 t X 10 2. 3
0 l S C H A R G f5. .. ( C. F. S.)
I
3
~ATING CURVE FOR SUSITNA RIVER AT SUSlT.NA STATION . · .. B~ll FIG .. AM3 _ __,._..,,.,· -~ REDRAWN FROM U,S.G.S. DISCHARGE. -TABLE N9 •. 02.
I
1
I
9-JIO
(~ev.l-67)
. JUNii~~}STAic::t beP"'"';:lENI urJTH~ ~~~.\Rit.,,.-:J
GEOLOGICAL SURVEY (WATER RESOURCES DIVISION)
:l ~-} .• .. ). -)
Sta. No. L ~ g 2 £. ...l. .2' e T
Table N.o. !2 Z
Rating table for __ ${t'.s_~/aa...RLV.ec...rl'LS(,!.si/.aa.. .. S-k.b"..a-.. -----------------------------------------------------------Begin - - -____ _
YR. MO. D, HR.
from .. Qt;;..tc 4 .l9.Z8 ..• to -------------------------------~ .from ________________________ to---·-------------------------,. from-----------------------to---------------------------------·--
Gage Diachorgc Differ-
heighr encc
F~tt Cfi Cfi
.00 ·----------
.10 ......................
.20 ................ ____
.30 .........................
.40 ···----.. --
.50 ----------
.60 ------
.70 ................. ---..: --·.·---
. 80 ilk,.4CJ2 .a.QQ
.90 z:z_gQq
7-00
.10
.lO
.)0
.40 .! ... Z.QQ
.8..QQ _,o tz._,.Q.OO -~U:?.9.
"'-~;2QQ
··t-· .:t£L.· ----...... .4~_7QQ
G~ge Discharge heoghr ·
F~tt Cfi
Differ·
ence
Cfi
Gage Discharge heighl
Fttr Cfi
Differ·
ence
Cfi
Gage
heighr
Fm
Gage h heighr Disc arge Differ· Discharge ence
Cfi Cfi F~tl Cfi
Differ·
ence
Cfi
Gage
heighr
Fttt
a.oo .3.b._,. --·-.9.QQ_ /o.oo ~,..7.! -LLQQ 12 .oo at_,.ZOQ !..3..9!2 ;Q .oo /Lf?l.tl..O.. ~.0.12 l/,.oo
.10 7,.4.((). .10 .7,J.L .. !.L?!P. .to 2,.~9.2 !.3..Qr1 .1o l.t.!-rZtXl-.1o
.2o 3B7 _EiQQ
.30 3.9.:?..Q2
.40 1lf4J.QQ_ .20.Q
.50 !IJ,_Q_QQ. /{2_Q.Q
.60 4ZJ.X:O. 1
.70 4~_Q[._.>Q_
.80 4.4,0.QQ
.90 #.S,OJ2<.'?.
q.oo tf.Gl;OO.Q.
.10 4.4-lXlQ
···r··
.20 .l3,202 /./.QQ .20 .,.B.02 1.4t!r2 .20
.JO ~(J.CK& !2..t?J2 .30 B~Z.... .30
.40 .I;"ZQQ Ao ..to t!.£?.,..5!2£ · .4o
.50 ti-..~4.... .50 .50 .lf3.,..{QQ_
.60 .60
.70 .70
.8o gz,zm .
.10
.60 tL9..,.1e2
.70 .i?L,.3.QQ
.80
.20 4.8/).QQ /.f2QQ .20 .20 9 i3,Jl!2Q.
.3o 9.9,.S:O.Q
.10 28,.9. --
.. 2o -:::Z.9.,..6Q;;
~t_,..3.QQ .3o 4..t;raa LtaQ .3o
.40 54/.00
.60
.70
.80 7.8_,.bQ2
.90 ?:~_0-QQ !J.Q_Q .9o Z9}~QQ l.J.QO
.70 .:3.871QQ
.ao • .3.~_ea J.ZQQ
.9o .4/,.St!?. tB..c;Q
Discharge
Cfi
1.4....~3.Q
.!I.S,.i£2C.
This table is applicable for open-channel conditions. It is based on 10 discharge measurements made during .!.9..22::].8 ____________ _
····--------···-------·····-------··---------------·-------------·--and is ___ f'a..t:t:f-----well defined between .£8r002cfs and .2£.?0r~cfs.
----.......... --........ -----... -... -.... -........ -----.. -............................. ---...... --..... -----..... ------·-· ... --------.......... -~------............ ----....................... ---.. -....... ---.. ---· --..................... _ .......... ---................ 4
Differ-Gage Discharge Dilfer-
encc heighr cncc
Cfi Fttt Cfi Cfi
.!Be; /£3.00
.10
.20
.30
.40
.10 -----------
.20 -----------
.30 -----------
.40 -----------
.50 -----------
.60
• 70 -----------
.80 -----------
.90 -----------
Comp. by~.(-date ~.-:llr.:.79
Ckd. by _________ date--~----·-
·-------------------... ·-----------·----·~------.. --... ·---------·----... --------·--------------------··----.---· .. --.. -----------.... --........................ -........................ _ ......... . U.l. GOVIINIIIIIT PIINTUIG OniCII IIU OI-J41-Jtl
9-2!0
(Rev. 2-67)
UNITED STATES DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY (WATER RESOURCES DIVISION)
Rnting table for _f..f~i!.._!_~_l}_ __ !f_(_t::_!!_!j_ __ d!:.. .. £J!.f..([_~!_-~~ 1':4 !:!..~_"Y_ _______________ ......................................... .
Sta. No. j_ £2-CJ. il-3 !7 q
Table No. C> 2-
Begin
Yll. 1.10, D. HR.
from Qf~:_!./1 _ _( l2Jl_ to ________________ " ______________ , .from.------------------_ to __ ---------___________ -------, . from_------------------------to _____ --------------------------------
Gage Discharg~ height
l'fll Cft
Differ·
ence
Cft
J9 .00 7.f?.4t9..0.. l 1.(10
;z. OJ )a:; -·-·-
.lo ··-·-------)._211 "
zo5SC'O -------
.20 -----------!!!:~E.
207~ -~0 ·----·--·---~!~.
.40 1:.C:..?..f..'?f! ll~e.
,)0
.60
~ .70
lIZ. "ZcC ---------.?lP~~
"2.1 1/)'(10 -----------2.1 (10
Yf&:?.. . ?.l.~
.ao 'Z:_t!.tE!?. -~1£'! .
. 90 J.'/:!Jt£/2 .l1DO
) o .00 fJJ.7P.E ;1~~~
7., ~'"1'(/i
.10 kk-.b.-: • .:-~ }J.~~
2283oo
;20 ---------·· J.1"o
01\ 2 "f ~(.CO ··-·····
'"" ····-······ l} DO
.40 '?}_~_1._'(Q _f.}q_~
.,o u~-~~-?-
.60
.70
.80
.90 1------------
Gage Discharge height
flfl Cft
.00
.ao
.20
.30
.40
.)0
.60
.70
.80
.90
.00
.10
.20
.30
.40
.)0
.60
.70
.80
.90
Differ·
ence
Cft
1-------
-------
Gage Discharge height
F111 Cft
.00 f-·----------
.10
.20
.30 1------------
.40
.• )0
.60
.70
.80
.90
.00
.10
.20 ---------
.30 ---------
.40
.)0
.60
.70
.80 ---------
.90 1-··---------
Differ·
ence
Cfs
1-------
Gage
h~ight
fill
.00
.10
.20
.30
.40
.)0
.60
.10
.80
.90
.00
.10
Discharge
Cft
.20 ---------
.30
.40
.)0
.60
.70
.80
~
.90
Differ·
ence
Cft
-------
-------
-------
Gage .
height Ducharge
1'111 Cfs
.00
.10
.20
.10
.40
.60
.70
.80
.90
.00
.10 ----------~-
.20
.30
.40
Dilfc:r·
~nee
Cft
1-·-·----
-------
--------
.60 r--------------------
.70
.80
.90
Gage
height Discharge
Ptll Cft
,00
.10 1------------
.20
.30
.40
.)0
.60
.70
.80
.90 f..-----------
.00
.10
.20
.30
.40
.)0
.60 ----------
.70 ---------
.80
.90 1-----------
This table is applicable for open-channel conditions. It is based on ____ discharge measurements made during -------------------····-------
-----··-·-------····················-··---------------------··-·--·-and is •• ·-······---------well defined between __________ cfs and --~-~-----·····rfs.
Differ·
~nee
Cft
-----·-··
Gage
height
I'll I
.oo
.10
.20
.30
.40
.)0
Discharge
Cft
.60 ~----------
.70
.80
.90
.00
.10 1------------·
.20
.30
.40
.)0
.60
.70
.80
.90 1------------
Cft
Comp. b.;J.!Jc'L date .ff..'!f_JP.)
Ckd. by········-date---------·
... 1. liOVIIM1111M1' PIUITUI~ OffiCI1 1117 OP-141 .. 711
.. t _c__j l .
APPENDIX B
FLOW VARIABILITY RATIOS
,-
r29/g2
-i -· -----· -------· -· -i
susl8/b1
Comparison of Peak Flows to Average Monthly-Flow
Susitna River at Gold Creek
No. 15292000
May
Mean Monthly .. 1 Dax Peak Flow 3-Da~ Peak Flow 7 ... Da~ Pe_ak Ffow 15-D~ Peak Flow
Year
Flow -QM Q1 91/QM .. Q3 Q3/QM Q7 Q7/QM Q15 Q15/QM (cfs)
1950 11510 21900 1 .. 90 20200 1.75 16700 1.45 16200 . 1.41 1951 14090 24700 1.75 23900 1.70 22500 1.60 17800 1.26 1952 5419 28000 5~ 17 26700 4 .. 93 17000 3.14 9570 1 .. 77 1953 19270 31000 1.61 30100 1.56 26400 1.37 22400 1 .• 16 1954 17280 23000 1.33 23000 1.33 22800 1.32 21600 1.25 1955 9319 1.95DO 2.Jl9 18300 1.96 17900 10"92 14500 1.56 1956 17660 39400 2 .. 23 36200 2.05 32400 1.83 26200 1 .. 48 1957 13750 31000 2.25 30500 2.22 28800 2.09 21800 1.59 1958 12900 25000 1.94 23700 1.84 21700 1.68 18500 1 .. 43 1959 1-5990 39600 2.48 37200 2.33 30700 1.92 27300 1 .. 7l 1960 15780 40000 2.53 35800 2 .. 27 27900 1.77 23700 1 .. 50 1961 17360 29400 1.69 26100 1 .. 50 22300 1.28 21700 1.25: 1962 12590 36000 2.86 29600 2 .. 35 23000 1.83 20300 1 .. 61 1963 19030 45000 2.36 42900 2.25 37100 1.95 33900 1.78 19o4 4307 37100 8.61 26400 6.13 14200 3.30 7740 1-80 1965 12900 37900 2.94 37300 2.89 30400 2 •. 36 21200 1.6fl 1966 9645 23300 2.42 22600 2.34 20400 .2.12 15300 1.5fJ 1967 15480 31200 2.02 30200 1.95 29700 1.92 24600 1 .. 59 1968 16177 39700 2.45 37000 2.29 33800 2.09 29100 1.80 1969 11045 26500 2.40 24400 2.21 20500 1.86 16200 1.47 1970 11380 21600 1.90 19500 1.71 18100 1.59 16300 1 .. 43 1971 3745 9500 2.54 8830 2.36 7640 2.04 5680 1.52 1972 21890 55500 2.54 43600 1.99 37000 1.69 29800 1.36 1973 8235 17000 2~06 16400 1.99 15400 1.87 13500 1 .. 64 1974 16180 33600 2.08 33200 2 .. 05 32400 2.00' 26400 11163 1975 15350 31000 2.02 30400 1,.98 28300 1.84 24100 1 .. 5'7 1976 126ZO 17000 ., 1 .. 35 16000 1.5:.5 15100 1.20 14000 1.11 1977 12680 33100 2.61 30400 2.40 24500 1.93 21500 1 ~ 7(~ 1978 11950 20500 1 .. 72 19400 1 .. 62 17700 1.~ 14900 1.2S 1979 13870 34400 2.48 33900 2.44 29400 2.12 22700 1.6~ 1980 12060 21000 1.74 20800 1 .. 72 17900 1 "48 15100 1.25 # rif VaL 31
Average 13270 2.45 2.24 1.87 1.51 Standard 4240 1 .. 33 0.95 0 .. 46 0.20 Oev ..
'::
susi8/b2
Year
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1 {~-:;,7
\'{<"' .. ""-
1978
10]Q . . ;~o;-•.1
1980
# of Val.
Average
Standard
Oev ..
Mean Monthly
Flow -QM
(cfs)
19600
20790
32370
27320
.25250
29860
33340
30160
25700
23320
15530
29450
43270
26000
50580
25720
3.2953
29513
31550
15503
"18630
32930
34430
27800
17870
32310
24380
37970
19050
24690
29080
31
27970
7740
Comparison of Peal< Flows to Average Monthly Flow
Susitna River at Gold Creek
No. 15292000
~une
1 Day Peak Flow 7 .... Day Peak Flow .
34000
35800
43300
37700
30100
38000
51500
40600
28000
29300
1870C
54000
79900
26000
85900
39900
58400
38800
39500
21900
30800
66300
70700
s2aoo
~;;··soo ~u .
44000
33300
52600
24300
32500
43200
--
1 ~73
1.72
1.34
1.38
1 .. 19
1.27
1 .. 54
1 .. 35
1.09
1.26
1 .. .20
1.83
1 .. 85
1.00
1.70
1.55
1. 77
1.31
1~:25
1.41
1.65
2 .. 01
2.05
1.90
1.67
1.36
1.37
1.39
1.28
1.32
1.49
1.49
0.27
!t
--
32100
32100
42300
37200
29500
37300
49900~
39900
28000
27900
17100
52000
75200
26000
81900
37200
56600
37400
38900
20900
30100
59000
65600
45300
27000
42200
32100
52200
23800
31200
40300
--' '
1.64
1.54
1.31
1.36
" 1 .. 17
1.25
1.50
1.32
1.09
'j ~20
1.10
1.77
1. 74
1.00
1 .. 62
1.45
1. 72
1.27
1.23
1 .. 35
1.62
·1.79
1.91
1.63
1 ·s1· .. ''• . •. ~
1 .. 31
1.32
., • 37
1 .. 25
1.26
1.39
1 .. 42
0.23
Q7 Q7/QM
27000
29800
39500
35500
28500
36000
46800
3B400
.28000
26000
16900
42700
64700
26000
75000
33000
49200
34800
38100
18700
26100
48300
53500
40900
22700
37100
29800
48300
23100
29400
34700
--
1.38
1.43
1.22
1.30
1.13
1.20
1.40
1.27.
1.09
1.11
1.09
1.45
1 .. 50
1.00
1.48
1.28
1.49
1.18
1.21
1.21
1.40
"1.47
1.55
1.47
1.27
1.15
1.22
1.27
1.21
1.19
1.19
1.28
0.15 ..--
15-Day Peak Flow
Q15 Q15/QM
22400
25200
31000
31000
25800
34600
40300
35400
28000
24300
16000
36800
53200
26000
63500
£7200
39800
31500
36500
17500
20400
38200
39800
34600
19700
32600
28600
41500
20601)
26400
31300
-
1.14
1.21
1.14
1 .. 13
1~02
1.16
1.21
1.17
1 .. 09
1 .. 04
1.03
1.25
1.23
1.00
, .26
1 .. 0~
1.21
1.07.
1.17
1.13
1.10
1 .. 16
1.16
1.24
1.10
1.01
1.17
1.09
1.08
1.07
1.08
1"13
0.'07
-'-
·I
j
I
j
I
~~~~-----------------~--~------------~------~~· ----------~----------------------------------~ --susl8/b3 --.. --· --···. .. -----..
Year
1950
. 1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965,
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
# of Val.
Average
Standard
Oev.
Mean Monthly
Flow -QM
(cfs)
22600
22570
26390
20200
20360
27560
31090
23310
22880
25000
22980
24570
25850
34400
22950
27840
19864
26800
26922
16103
22660
23950
22770
18250
'18800
27720
18940
22870
21020
28880
32660
31
24150
4240
Compat~ison of Peak Flows to Average Monthly Flow
Susitna River at Gold Creek
No. 15292000
July
1 Day Peak Flow 3-Day Peak Flow . 7-Day Peak Flow
32500
25000
41700.
26200
28700
39000
32000
34500
32400
32000
37500
30300
32700
49000.
33200
37700
31800
50000
32000
20900
29100
38300
27200
22900
26300
33900
22800
30000
24100
39300
49700
1.44
1.11
1.58
1.30
1 .. 41
1.42
1 .. 03
1.48
1.42
1.28 '
1.63
·1.23
1.26 .
1.42
1.45
1.35
1.60
.1.87
1.21
1.30
1.28
1.60
1.19
1.25
1.40
1.22
1.11
1 .. 31
1.15
1.36
1.52
1.36
0.18
Q3 Q3/QM
29600
24800
40400
24300
26600
38300
32000
31300
32100
30700
36100
27100
28600
46300
29100
34900
29800
46300
31600
20200
27700
35800
26400
22400
25000
32500
21600
29700
23300
34800
45100.
1.31
1.10
1.53
1 .. 20
1.31
1.39
1.03
1.34
1. 40
1.23
1.57
1.10
1.11
1.35
1.27
1.25
1.50
1.73
1.20.,
1.25
1.22
1.49
1.16
1.23
1.33
1 .. 17
1.14
~ 1.30
··1.11
1 .. 20
1 .. 38
1.29
0 .. 16
26300
24600
33900
22800
24500
34200
32000
26300
25900
29500
32900
26100
27700
42900
27100
32000
25100
38900
29400
19100
25000
31800
25500
22200
21900
30700
19700
27900
22500
32600
36800
1.16
1.09
1.28
1.13
1.20
1.24
1.03
1.13
1.13
1.18
1.43
1.06.
1.07
1.25
1018
1.15
1.26
1.45
1.11
1.19
1.10
1.33
1.12
1.22
1 .. 16
1.11
1.04
1.22
1.07
1.13
1.13
1.17
0.10
---
15-Da:y Peak Flow_
Q15 Q15/QM
24500
23800
29100
21000
21800
30900
32000
24900
23800
26500
26100
25500
26600
39200
25800
30500
21800
32500
28400
17700
230QO
26500
25500
20300
20300
29200
19300
25100
21600
31700
33700
1.08
1.05
1.10
1.04
1.07
1.12
1.03
1.07
1.04
1.06
1.14
1.04
1 .. 03
1.14
1.12
1.10
1.10
1.21
1 .. 07
1 .. 10
1.02
1.11
1.12
1.11
1.08
1.05 ,,
1 .. 0.2
1.10
1.03
1.10
1.03
1.08
0.04
~ <Ill,): ' • tl • ' • .. • • • • •• ~. ' • • •" .... •• • & •·
susi8/b4
Comparison of Peak Flows to Average Monthly Ffow
Susitna River at Gold Creek
No. 15292000
August
Mean Monthly 1 Da~ Peak Flow 3··DaY: Peak Flow 7..:.oa~ Peak FJow 15-Da]t· Peak Flow
Year
Flow -QM Q1 o,loM Q3 Q3/QM Q7 Q7/QM Q15 o,510M (efs)
1949 24250 35000 1.44 34000 1.40 31900 1.32 30900 1.27 1950 19880 27600 1.39 26200 1 .. 32 24800 1.25 23600 1 .. 19 1951 19670 30600 1.56 26900 1.37 24200 1.23 21100 '1.07 1952 20920 41900 2-00 37400 1.79 30100 1.44 26800 1 .. 28 1953 20610 28100 1.36 26600 1.29 25400 1.23 22100 1,.07 1954 26100 41000 1.59 40300 1.54 33300 1.28 28300 1 .. 08 1955 25750 5690(\ 2.21 54000 2.10 43100 1.67 .. 29900 1.16 1956 24530 31000 1.26 31000 1.26 30900 1.26 28600 1 .. 17 1957 20540 2660() 1.30 24900 1.21 21400 1·.04 20900 1.02 1958 2~540 47800 2.12 • 45900 2.04 38300 1.70 30200 1.34 1959 31180 59700 1 .. 91 56700 1.82 49100 1.57 41700 1-34 1960 23590 33300 1.41 30500 1.29 27700 1.17 25600 1.09 1961 •22100 26000 ¢1.18 . 2600J 1.18 26000 1.18 26000 1.18 1962 23550 30600 1.,30 2871)0 1.22 25500 1.08 24100 1 .. 02 1963 23670 35000 1.48 31!700 1.38 30300 1.28 25400 1.07 1964 16440 21600 1.31 21500 1.31 20200 1.23 18100 1.10 1965 21120 33600 1.59 33000 1~56 30600 1.45 26000 1 .. 23 1966 21825 33500 1.53 31400 1.44 26900 1.23 .23200 1 .. 06 1967 32622 76000 2.33 69300 2.12 55400 1.70 42200 1.29 1968 17167 21800 1.27 21600 1.26 20500 1.19 19900 1.16 1969· 8879 16800 1.89 15800 1. 78 14300 1.61 1210f} 1.36 1970 19980 31600 1.58 29500 1.48 26100 1. 31 22900 1.15
I
1971 31910 77100 2.40 72700 2.28 57900 1 .. 81 41900 1.31 . 1972 19290 26400 1.37 24900 1.29 22200 1.15 21000 1.09 1973 20290 30500 1.50 29900 1.47 27800 1.37. 21300 1.05 1974 16220 22300 1.37 21300 1.31 18900 1.17 17600 1.09 1975 18090 24800 1 .. 37 23400 1.29 21600 1.19 19900 1.10 1976 1980\1 32000 1.62 30000 1.52 28600 1 .. 44 24900 1.26 1977 19241J 26200 1.36 24600 1.28 23400 1.22 21500 1,.12 1978 163~fJ 20900 1·.28 20800 1.27 20500 1.25 19500 1 .. 19 1979 20460 28400 1.39 27600. 1 .. 35 25800 1.26 24000 1.17 1980 20960 31100 1.48 27700 1.32 24500 1.17 24100 1 .. 15 #of Val. 32
Average 21550 1.57 1 .. 49 1 .. 33 1 .. 16 Standard 4725 0.33 0.30 0.20 0.10 .v .. _ ---------'------' ' .
{.~ ..
.. ----··-·----susi8/b7 -.. ---
Mean Monthly
Year
Flow-.QM
(cfs)
1958 10460
1959 7413
1960 13890
1961 10100
1962 7743
1963 11060
1964 2355
1965 7452
1966 3971
1957 12400
1968 10940
1969 6001
1970 9643
1971 4468
1972 9765
#of VaL 15
Average 8510
Standard 3270
D~v.
Comparison of .Peak Flows to Average Monthly Flow
Chulitna River near Talkeetna
No. 15292400
May
1 Da~ Peak Flow 3-Dai: Peak Flow
Q3/"~M
;~j
7-Da~ Peak Flow
Q1/QM Q, Q1/QM Og Q7
16000 1.53 16000 1.53 16000 1.53
13000 1.75 13000 1.75 12700 1 .. 11
35700 2.57 33300 2,40 29600 2 .. 13
16000 1.58 15000 1,.50 13100 1~30
16500 2.13 16000 2.07 14900 1.92
28500 2.58 26600 2.41 22600 2.04
4000 1.70 4000 1.70 4000 1.70
12000 1.61 12000 1 .. 61 '12000 f .61
911(} 2~29 . 6700 1.68 6020 1.52
22000 1 .. 77 21000 1 .. 6;;} 20700 1.67
25400 2.32 23900 2 .. 18. 22200 2.03
12300 2.05 11700 1.95 ~0100 1.68
19000 1.97 17700 1 .. 83 16100 1.67
11000 2.46 10300 2.31 8860 1.98
23800 2.44 20000 2.05 16700· 1. 71
2.ff'S 1.~1 1.75
0.:18 0.31 0.23
I ~-
15-Da~ Peak Flow
Q15 Q15/QM
14200 1.-36
11300 1.52
21500 1 .. 55
12700 1.26
12200 1.58
19600 1. 77
3330 1.41
1200.0 1.61
5740 1.45·
18100 1 .. 46
18400 1.63
8160 1.36
13900 1.44
6710 1.50
12800 1 .. 31
1.48
0.14
susi8/b8
Mean Monthly
Year
Flow -QM
(cfs)
1958 23170
1959 23660
1960 17~90
1961 20490
1962 20620
1963 17750
1964 40330
1965 20070
1966 21740
1967 25520
1968 29000
1969 18560
1970 19670
1971 22180
1972 17900
'1980 22490
#ofVal. 16
Average 22530
Standard 5650
Dev.
Comparison of Peak Flows to Average Monthly Flow
Chulitna River near Talkeetna
No. 15292400
June
1 Da~ Peak Flow 3-Da~ Peak Flow 7-Da~ Peak Flow
Q77QM Q1 Q1/QM Q3 Q3/QM Q7
29000 1.25 28300 1.22 27300 1.18
33400 1.41 33100 1.40 32300 1.37
22000 1.27 21700 1.25 21200 1.22
.29200 1.43 27600 1.35 25900 1.26
38000 1.84 34100 1.65 29700 1.35
27700 1.56 24300 1.37 23000 1.30
45000 1.12 45000 1.12 45000 1.12
30000 1.49 28000 1.40 24900 1.24
29000 1. 33 27700 1.27 26100 1.20
56000 2.19 40800 1.60 34300 1.34
38800 1. 34 37900 1.31 35900 1.24
28100 1. 51 26300 1.42 24800 1. 34
33000 1.68 29700 1. 51 25400 1.29
44500 2.01 41600 1.88 38300 1. 73
28000 1.56 25800 1.44 23300 1.30
30200 1.34 27400 ·1.22 25000 1.11
1.52 1.40 1.29
0.29 0.19 0.14
I .. J
15-Da~ Peak Flow
Q15 0 15/QM
23900 1.03
29500 1.25
19100 1.10
24900 1.22
25300 1.23
18900 1.06
43000 1.07
21900 1.09
24100 1.11
30200 1.18
33600 1.16
24500 1.32
21600 1.10
28400 1.28
20300 1.13
23700 1.05
1.15
0.09
.J
--) . ---=1
susi8/b9
Mean Monthly
~
Flow -QM
(cfs)
1958 25010
1959 25650
1960 23650
1961 27420
1962 27720
1963 28950
1964 24930
1965 23230
1966 23750
1967 35570
1968 30140
1969 20820
1970 26100
1971 27280
1972 25770
1980 34950
# of Val. 16
Average 26930
Standard 3980
Oev.
.. -... ; . -l
Comparison of Peak Flows to Average Monthly Flow
Chulitna River near Talkeetna
No. 15292400
July
1 Da~ Peak Flow 3-Day Peak Flow 7-0a~ Peak Flow
o 1 o 17oM Q3 Q3/QM Q7 Q7(QM
31700 1. 27 30700 1.22 27700 1.11
36400 1. 42 31500 1.22 30200 1.18
33400 1.41 31500 1. 33 29300 1.29
38900 1. 42 36500 1.33 32800 1.20
36800 1.35 32900 1. 21 31000 1.14
34000 1.17 34000 1.17 34000 1.17
27000 1.08 27000 1.08 27000 1.08
27400 1.18 27100 1.17 26400 1.14
30500 1.28 29900 1.26 28700 1. 21
71200 2.00 61400 1. 73 47300 1.33
35400 1.17 35000 1.16 33600 1.11
26000 1.25 24700 1.19 24000 1.15
34800 1.33 33200 1.27 30200 1.16
42600 1.56 40100 1.47 35900 1.32
34100 1.32 33600 1.30 33100 1.28
55800 1.60 47900 1.37 40800 1.17
1.36 1.28 1.19
0.22 0.15 0.08
15-Da~ Peak Flow
Q15 015/QM
26100 1. 04
29100 1.13
25700 1. 09
30200 1.10
29600 1.09
34000 1.17
26000 1.04
24800 1.07
27100 1.14
40900 1.15
31700 1.05
23800 1.14
28200 1.08
31800 1.17
29700 1.15
38500 1.10
1.11
0.04
susi8/b10
Mean Monthly
~
Flow -QM
(cfs)
1958 20760
1959 22100
1960 19320
1961 24580
1962 21980
1963 18390
1964 20250
1965 22550
1966 27720
1967 33670
1968 20710
1969 11300
1970 24660
1971 23810
1972 20970
1980 20780
# of Val. 16
Average 22100
Standard 4690
Dev.
Comparison of Peak Flows to Average Monthly Flow
Chulitna River near Talkeetna
No. 15292400
August
1 Day Peak Flow 3-0a~ Peak Flow
Q3/QM
7~Da~ Peak Flow
Q7 Q7/QM Q1 Q1/QM Q3
33800 1.63 31900 1.54 29100 1.40
34000 1.54 29100 1.32 28000 1.27
25000 1.29 25000 1.29 25000 1.29
40000 1.63 37700 1. 53 33600 1.37
36700 1.67 32700 1.49 26600 1.21
20000 1.09 20000 1.09 20000 1.09
28000 1.38 25800 1. 27 23100 1.14
34400 1.53 34000 1.51 31700 1.41
37600 1.36 36700 1.33 34800 1.26
73000 2.17 71000 2.11 56300 1.67
29800 1.44 29000 1.40 26800 1.29
22500 1.99 21400 1.89 18800 1.66
35600 1.44 33700 1.37 31500 1.40
45000 -1.89 40900 1.72 36100 1.52
27200 1.30 25800 1.23 24400 1.16
32500 1.56 28100 1.35 26500 1.28
1.56 1.47 1.34
0.28 0.26 0.17
_) ... I
15-Da}! Peak Flow
Q15 Q15/QM
25900 1.25
25300 1.14
25000 1.29
27600 1.12
23200 1.06
19700 1.07
21300 1.05
27700 1.23
29300 1.06
42200 1.25
24600 1.19
15100 1.34
27600 1.12
29400 1.23
22700 1.08
25200 1.21
1.17
0.09
~ · .
cl • -] •.. . ) !
susi8/b11
Mean Monthly
Year
flow -QM
(cfs)
1958 8000
1959 9957
1960 12420
1961 16030
1962 13490
1963 11330
1964 9235
1965 22260
1966 12200
1967 12510
1968 7375
1969 6704
1970 11330
1971 11080
1972 12120
1980 3240
# of Val. 16
Average 11520
Standard 3770
Dev.
Comparison of Peak Flows to Average Monthly Flow
Chulitna River near Talkeetna
No. 15292400
September
1 Oa~ Peak Flaw 3-Day: Peak Flow 7-Day: Peak Flow
Q1 0/QM Q3 Q3/QM Q7 Q7/QM
9200 1.15 9200 1.15 9200 1.15
20200 2.03 18600 1.87 15700 1.58
23000 1.85 21000 1.69 18000 1.45
30700 1. 92 28200 1. 76 23200 1. 45
35500 2.63 30500 2.26 24400 1.81
14000 1.24 14000 1.24 14000 1.24
15000 1.62 14000 1.52 13000 1. 42
41100 1. 85 34800 1.56 30800 1.38
18000 1.48 17000 1.39 14600 1.19
21700 1.73 20600 1.65 17500 1.40
10500 1.42 10300 1.40 9810 1.33
9680 1.44 9390 1.40 8760 1. 31
19300 1.70 19000 1.68 17900 1.58
16900 ' 1.53 16600 1.50 16000 1.44
29100 2.40 25300 2.09 19300 1.59
12900 1.57 12000 1.46 10400 1. 26
1.72 1.60 1.41
0.39 0.29 0.17
15-Day Peak Flow
Q15 Q15/QM
9200 1.15
12400 1. 25
15600 1.26
19300 1.20
18000 1.33
12700 1.12
11000 1.19
23900 1.07
13700 1.12
16100 1.28
9330 1.27
7980 1.19
15400 1.36
14500 1. 31
16400 1. 35
8830 1.07
1.22
0.10
susi8/b12
Mean Monthly
Year
Flow -QM
(cfs)
1958 4195
1959 4723
1960 5135
1961 5777
1962 3506
1963 8062
1964 5642
1965 6071
1966 4682
1967 3483
1968 2898
1969 4578
1970 3826
1971 5439
# of Val. 14
Average 4858
Standard 1324
Dev.
) 3
Comparison of Peak Flows to Average Monthly Flow
Chulitna River near Talkeetna
No. 15292400
October
1 Da~ Peak Flow 3·Da}:: Peak· Flow 7-Da}:: Peak Flow
Q1 Q1/QM Q3 Q3/QM Q7 Q7/QM
6200 1. 48 6000 1.43 5600 1.33
7800 1.65 7400 1.57 -7070 1.50
10900 2.12 9750 1. 90 8800 1. 71
12500 2.16 11600 2.01 10100 1. 75
7820 2.23 7190 1.82 6380 1.82
12000 1.49 12000 1.49 12000 1.49
15300 2.71 12700 2.25 10000 1. 77
9400 1.55 9400 1.55 9400 1.55
8500 1.81 8170 1.74 8000 1. 71
5800 1.67 5600 1. 50 5180 1.49
4400 1.52 4150 1. 43 3820 1.32
7700 1.68 6960 1.31 6010 1.25
5000 1. 31 4930 1.29 4770 1.25
11000 2.02 10300 1.89 8830 1.62
1.81 1.66 1.54
0.38 0.28 0.20
' I
15-0a~ Peak Flow
Q15 Q15/QM
5030 1.20
6030 1.28
7140 1.39
7750 1.34
5050 1.44
10300 1.28
7580 1.34
9400 1.55
6630 1.42
4520 1.30
3480 1.20
5740 1.25
4450 1.16
7050 1.30
1.32
0.11
j
~-'"_,, I : j ,J
---~usi8/b13
Mean Monthly
Year
Flow -QM
(cfs)
1955 3474
1966 2410
1967 4112
1968 8840
1969 3869
1970 3950
1971 2145
1972 3516
1973 3860
1974 5678
1975 4084
1976 3439
1971 4244
1978 2950
1979 7790
1980 4820
# of Val. 16
Average 4324
Standard 1782
Dev.
---.;-.. . i . ' ---
Comparison of Peak Flows to Average Monthly Flow
Talkeetna Riv~r near Talkeetna
No. 15292700
May
"
"
1 Dal: Peak Flow 3-Da~ Peak Flow 7-0a)! Peak Flow o, Q1/QM Q3 Q3/QM Q7 Q7/QM -
14300 4.12 12100 3.48 9060 2.61
5890 2.44 5750 2.39 5020 2.08
750J 1.82 7430 1.81 7360 1.79
19000 2.15 17500 1.98 16600 1.88
13500 3.49 11100 1.87 8430 2.18
7900 2.00 7520 1.90 6690 1.69
4980 2.32 4940 2.30 4420 2.06
12600 3.58 10400 2.96 8520 2.42
6920 1.79 6770 1.75 6640 1.72
15000 2.64 14400 2.54 13000 2.29
12200 2.99 11900 2.91 10100 2.47
0 5000 1.45 4500 1.31 4110 1.20
12800 3.02. 12500 2.95 9530 2.25
4750 1 .. 61 4670 1.58 4340 1.47
20700 2.66 20200 2.59 16700 2.14
10000 2.07 9670 2. o·1 8170 1.70
2.51 2.33 2.00
0.76 0 .. 60 0.39
15-Da~ Peak Flow
Q15 Q15/QM.
5890 1.70
3700 1 .. 54
6140 1 ~49
14600 1 .. 65
6000 1.55
5630 1.43
3360 1.57
5790 1.65
5840 1.51
9340 1.64
7210 1.77
3880 1.1:8
7090 1.6V
3870 1.31
11800 1.51
6650 1.38
-1.53
0.16
susi8/b14
Year
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
# tlf Val.
Average
Standard
Dev.
Mean Monthly
Flow -QM
(cfs)
17080
11090
12970
9286
14100
5207
7979
19040
12700
12210
. 8030
13180 .
10580
18280
7429
12010
11380
17
11910
3800
Comparison of Peak Flows to Average Monthly Flow
Talkeetna River near Talkeetna
No. 15292700
June
1 Day Peak Flow_ ,_ 3-Day Peak Flow 7-0ay Peak Flow
Q1 ·o1/QM
27000
16700
24000
15400
22000
7120
17900
33700
27500
25000
14100
18600
17200
27100
12900
20500
15000
1.58
1<t51
1.85
1.66
1.56
1.37
2.24
1.77
2.17
2.05
1.76
1.41
1.63
1.48
1.74
1.71
1.32
1.69
0.27
Q3 Q3/QM
25000
15200
23400
13400
20500
6800
16500
30200
22400
21200
11200
15900
16200
24700
9900
19200
14700
1.46
1.37
1~80
1.44
1.45
1.31
2.07
1.59
1. 76
1u74
1.39
1.21
1.53
1.35
1.33
1.60
1.29
1.51
0.22
23000
13600
21200
11500
18200
6060
11700
26500
17000
19200
9420
14300
15000
23500
8920
17000
12900
1.35
1 .. 23
1 .. 63
1.24
1.29
1.16
1.47
1.39
1 .. 34
1 .. 57
1.17
1.08
1.42
1.29
1.20
1 .42
1 ... 13
1.32
0.15
15-Da}~ Peak Flow
Q15 Q15/QM _ _,.,.. ___ _
20400
12300
16400
11100
16300
'5880
9060
22900
14200
15600
8670
14100
12900
20900
7870
14000
11800
1.19
1 .. 11
1.26
1.20
1 .. 16
., 1.13
1.14
1,.20
1.12
1.28
1 .. 08
1.07
1.2?
1.14
1.06
1.17
1.04
1.15
0.07
----, •.• -,,.. -----;---i--,. ' . , ' ;.,
susi8/b16
Mean Monthly
Year
Flow -QM
(cfs}
1964 8396
1965 11150
1966 10730
1967 14160
1968 7546
1969 3787
1970 8752
1971 16770
1972 9576
1973 9927
1974 7704
1975 8487
1976 8088
1977 8005
1978 7001
1979 8274
1980 7220
# of Val. 17
Average 9151
Standard 2922
Dev.
-~-~ 0 ••
Comparison of Peak Flows to Average Monthly Flow
Talkeetna River near Talkeetna
No. 15292700
August
1 Da~ Peak Flow 3-Da:t Peak Flow 7-Da:t Peak Flow
Q1 o11oM Q3 Q3/QM Q7 Q7/QM
11900 1. 42 11100 1.32 11000 1.31
21400 1. 92 20900 1.87 17900 1.61
19800 1.85 19100 1. 78 15100 1. 41
34700 2.45 27600 1.95 23600 1.67
9900 1.31 9200 1.22 8290 1.10
7900 2.09 7450 1. 97 6810 1.80
12700 1.45 11600 1.33 11100 1.27
63000 3.76 50400 3.01 35800 2.13
14000 1.46 13700 1. 43 12900 1.35
24000 2.42 21300 2.15 16400 1.65
18800 2.44 14300 1.86 9330 1.21
12900 1.52 12100 1. 43 10200 1.20
11700 1.45 10500 1. 30 10200 1. 26
11300 1. 41 9990 1.25 9390 1.17
10500 1.50 10200 1.46 9440 1.35
15800 1.91 15000 1. 81 12600 1.52
12700 1.76 11100 1.54 9630 1.33
1.89 1.69 1. 43 °
0.62 0.45 0.27
. .~
15-Da:t Peak Flow
Q15 01s/OM
9650 1.15
14600 1. 31
12400 1.16
18500 1. 31
8020 1.06
5400 1.43
9790 1.12
24300 1.45
10600 1.11
11600 1.17
7760 1.01
9770 1.15
9420 1.16
8550 1.07
8740 1.25
10200 1.23
8500 1.18
1.19
0.12
--------------· susi8/b17
Comparison of Peak Flows to Average Monthly Flow
Talkeetna River near Talkeetna
No.. 15292700
September
Mean Monthly 1 Day Peak F!O\V 3-Da~ Peak Flow ~ 7-Da~. Peak Flow
Year
Flow -QM
(cfs)
Q1 Q1/QM Q3 Q3/QM Q7 Q7/QM
1964 3815 5100 1.34 5000 1.31 4690 1.23
1965 10610 23400 2.21 19000 1.79 16600 1.56
1966 5370 8900 1.66 7400 1.38 6410 1.19
1967 6971 13300 1.91 13100 1.88 12100 1. 74
1968 4120 6640 1.61 6380 1.55 5730 1.39
1969 2070• 3220 1.56 2970 1.43 2660 1 .. 29
1970 5993 14700 2.45 12600 2.10 9910 1.65
1971 5990 12000 2.00 11000 1.84 9640· 1.f51
1972 8709' 19800 2.27 16200 1 .. 86 13300 1.53
1973 3861 . 7500 1. 94 6830 1.77 5860 1.52
1974 4763 9200 1.93 8540 1.79 7120 1.49
1975 7960 14900 1.87 13600 1 .. 71 10700 1.34
1976 3205 4010 1.25 3790 1.18 3410 1.06
1977 5826 8450 1.45 8030 1.38 7260 1.25
1978 3513 6400 1.82 5450 1 .. 55 4770 1.36
1979 4039 6760 1.67 6080 1.51 5860 1.45
1980 5400 18600 3 .. 44 14900 2.76 10400 1. 93
# of Va_l. 17
Average 5428 1.91 1.69 1.45
Standard 2192 0.51 0.37 0.22
Dev.
----
15-Da~f Peak Flow
Q15 Q15/QM
4180 1.10
13200 1.24
6050 1.13
9630 1.38
5290 1.28
2400 1.16
7310 1 .. 22
7830 1 .. 31
11400 1.3.1
4830 1.,25
5390 1.13
9970 1 ~2~
3280 1.0?
6840 1.17
4350 1.24
4560 . 1.13
7440 1.38
1.22
0.10
susi8/b18
J
Comparison of Peak Ffows to Average Monthly Flow
Talkeetna River near Talkeetna
No. 15292700
October
Mean Monthly 1 Da~ Peak Fiow g ... oa~ Peak Flow 7-Day Peak Flow 15·Da~ Peak Flow
Year
Flow -QM Q1 0 1 /QM Q3 Q3/QM Q7 Q7/QM Q15 Q15/QM (cfs)
1964 3115 4820 1.55 4610 1.48 4180 1.34 3840 1.23 196'.) 4438 10200 2.30 9050 2 .. 04 7610 1. 71 S080 1.37 196S 2388 4170 1. 75 3970 1.66 3610 1.51 3200 1.34 ·iS67 2029 2940 1.45 2860 1. 41 2560 1.31 2440 1.20 1968 1637 2280 1.39 2200 1.34 2080 1.27 1920 1. '17 1969 1450 2100 1.45 2070 1.43 1910 1.32 1730 1.19 *1970 2817 5200 1.85 4570 1.62 3870 1.37 3430 1.22 1971 2632 3600 1.37 3530 1.34 3170 1.20 3090 1.17 1972 3630 6120 1.69 5510 1.52 4750 1.31 4090 1.13 1973 1807 3000 1.66 2760 1.53 2560 1.42 2240 1.24 1974 1987 3260 1.64 3110 1.57 2810 1.41 2480 1.25 1975 2884 5100 1~77 4830 1.67 4480 1.55 3950 1.37 1976 ' 1857 2400 1.29 2270 1.22 2200 1.18 2040 1.10 1977 3268 5400 1.65 5020 1.54 4520 1.38 4080 1 .. 25 1978 1660 2380 1.43 2310 1.39 2090 1.26 1830 1.18 1$79 3371) 6700 1.99 5870 1. 74 5120 1.52 4270 1.27 # of Vat. 16
Averag~ 2559 1.64 1.53 1.38 1.23 Standard 854 0.26 0.19 0.14 0.08 I) Dev.
-----------------. --. , . . ; -
-susi8/b19
,..1_3·
Mean Monthly
Flow -Q
Year (cfs). M
1975 47540
1976 70460
1977 56180
1978 48670
1979 81260
1980 66580
#of VaL. 6
Average 61780
Standard 13295
Dev.
--------
Comparison of Peak Flows to Average Monthly Flow
Susitna River. at Sus,itna Station
No. 15294350
May
-
1 bay: Peak Flow 3-0a~ Pea~c Flow 7-Day Peak Flow
Q7/QM Q1 Q 1/QM Q3 Q3/QM Q7
121000 2~55 114000 2.40 103000 2.17
115000 1 r..63 113000 1.60 101000 1.43
128000 2.28 121000 2.15 105000 1.87
66000 1.36 65300 1.34 62800 1.29
136000 1.67 134000 1 .. 65 121000 1.49
124000 1.86 116000 1.74 99200 1.49
"
1.89 1.81 1.62
0.44 ' 0.39 0.33
.... • .. • \. •. • <I • ..
- -
15-0ay Peak Flow
Q15 Q15/QM
81000 1.70
83100 1.18
91000 1.62
58800 1.21
105000 1.29
85100 1.28
1.38
0.22
susi8/b20
Mean Monthly
Year
Flow .... QM
(cfs)
1975 128800
1976 107000
1977 165900
1978 90930
1979 119900
1980 142900
#of Val. 6
Average 125900
Standard 26510
Oev.
0
Comparisbn of Peak Flows to Average Monthly Flow
Susitna River· at Susitna Station
No. 15294350
June
1 Day Peclk Flow ___1:. gay Peak Flow 7-Day Peak · Flow
Q1 Q1/QM G:3 Q3/QM Q7 Q7/QM
161000 1.25 152000 1.18 141000 ·1.09
131000 1.22 13000 1. 21 128000 1.20
195000 1.18 191000 1.15 186000 1.12
118000 1.30 114000 1.25 113000 1.24
158000 1.32 150000 1 .. 25 133000 1.11
173000 1.21 . 164000 1.15 152000 1.06
1.25 1.20 1.14
0.05 . 0 .. 05 0.07
15-Day Peak Flow
Q15 Ql5/QM
137000 1.06
116000 1.08
175000 1.05
·103000 1 .. 13
122000 1.02
149000 1 .. 04
1.06
0 .. 04
~------------------
I
' . --· --- - - -·-- - - - ----: - -susi8/b21
Mean Monthly
Year
Flow -QM
(cfs)
1975 135700
1976 115200
1977 143900
1978 117600
1979 142500
1980 181400
# of Val. 6
Average 139380
Standard 23950
Dev.
Comparison of Peak Flows to Average Monthly Flow
Susitna River at Susitna Station
No. 15294350
July
1 Da~ Peak Flow 3-Da}::: Peak Flow 7-Da~ Peak flow
Q1/QM o, Q3 Q3/QM Q7 Q7/QM
171000 1 .. 26 159000 1.17 155000 1.14
'146000 1.27 139000 1.21 126000 1.09
166000 1.15 161000 1.12 152000 1 .. 06
130000 1.11 126000 1.07 120000 . 1.02
175000 1.23 169000 1.19 155000 1.09
226000 1.25 215000 1.19 203000 1.12
1.21 1.16 1.09
0.07 0.05 0.04
15-Da,l! Peak Flow
Q15 01s/QM
148000 1.09
123000 1.07
1.46000 1.01
119000 1.01
153000 1 .. 07
189000 1.04
1 .. 05
0.03
~
I
susi8/b22
Mean Monthly
Flow -Q
Year (cfs) M
1975 91360
1976 99650
1977 125500
1978 102100
1979 128200
1980 126400
#of Val .. 6
Average 112200
Standard 16300
Dev •
. F
---·:
~ ' -)r<
Comparison of ...,,. ·;. Flows to Average Monthly Flow
Susitna River at Susitna ·Station
Noo 15294350
August
1 Da~ Peak FJow 3-Da~ Peak_ Flow 7-Da}! Peak ·F!ow
Q 1 Q1/QM Q3 Q3/QM Q7 Q7/QM
113000 1.24 109000 1 .. 19 105000 1.15
138000 1.38 134000 1.34 125000 1 .• 25
151000 1,.20 144000 1.15 141000 1.12
130000 1.27 130000 1.27 126000 1.23
160000 1.25 157000 1.22 146000 1.14
163000 1.29 153000 1.21 142000 1.12
1.27 '1.23 1.17
0.06 0.07 0.06
------
15-Dav. Peak Flow
Q15 Q15/QM
99800 1 .. 09
115000 1.15
135000 1.08
120000 1.17
141000 1'" 10
141000 1 ~ 12
1.12
0.04
--.---
--· --•.•..• , •. (--•. - - - - -·-- -susi8/b23
Mean Month!y
Year
Flow-QM
(cfs)
1975 77740
1976 48910
1977 83810
1978 55500
1979 74340
1980 91200
# of Val. 6
Average 71910
Standard 1£?440
Dev.
Comparison of Peak Flows to Average Monthly Flow
Susitna River· at S.usitna Station
No. 15294350
September
1 Da~ Peak Flow 3-Da}!: Peak Flow 7-Day Peak Flow
Q1 Q1/QM Q3 Q/Q 3 M Q 7 Q7/QM
122000 1.57 110000 1.41 100000 1.28
93800 1.92 •84100 1. 72 69700 1.43
119000 1.42 109000 1.,30 99600 1.19
83400 1.50 77900 1.40 72100 1 .. 30
118000 1.59 113000 1.52 108000 1,.45
'' 135000 1 ~48. ' 122000 1.34 108000 1.18
1.58 1.45 1.31
0.18 ' 0 .. 15 0.12
. .
15-Day Peak Ffow
Q15 Q15/Q~
93800 1.21
.5€400 1.15
92000 1 .. 10
69200 1.25
!l\0900' 1 .. 22
98600 1.08
1.17
0.07
susi8/b24
Mean Monthly
Year
Flow -QM
(cfs)
1974 19520
1975 31550
1976 30140
1977 38230
1978 36810
1979 58640
# OtVal. 6
Average 35815
Standard 12990
Dev.
J .
Comparison of Peak Flows to .H.verage Monthly Flow
Susitna River at Susitna Station
No. 15294350
October
1 Da~ Peak Flow 3-0a~ Peak Flow 7-Da~ Peak Flow
Q1 o11oM Q3 Q3/QM Q7 Q7/QM
35000 1. 79 30000 1.54 26300 1.35
61000 1.93 54600 1.73 45400 1.44
43000 1.43 36000 1.19 33000 1.09
77400 2.02 68400 1. 79 56700 1.48
50000 1.36 48000 1.30 45400 1.23
93300 1.59 90600 1.55 86000 1.47
1.69 1.52 1.34
0.27 0.23 0.16
. J ..·~·J
15-Da~ Peak Flow
Q15 Q15/QM
25200 1.29
39400 1.25
31000 1.03
51000 1.33
43500 1.18
74800 1.28
1. 23
0.11
--·---: -t-·• ~ - - - -:--.... - -susi8/b25
Year
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971 .
1972
1,973
1974
1'975
-1976
1977
1978
1979
1980
# of Val.
Average
standard
Dev.
Mean Monthly
Flow -QM
(cfs)
14090
5419
14270
19280
9319
17660
13750
12900
15990
15780
17360
12590
19030
4307
12900
9645
-15480
16177
11045
11380
3745
21890
8235
16180
15350
12620
12680
11950
13870
12060
31
13270
4240
Comparison of Low Flows to Average Monthly Flow
Susitna River at Gold Creek
1 Day Peak · Flow
5200 0.37
1100 0.20
10700 0.56
8800 0.51
4500 0.48
1500 0.08
4300 0.31
3420 0.27
3400 0.21
7600 0.48
9000 0.52
4500 0.36
3400 0.18.
900 0.21
2200 0.17"
3400 0.35
1700 0.11
2200 0.14
3200 0.29
1800 0.16
1400 0.37
2500-0.11
1400 0~17
2200 0.14
2500 '0.16
3800 0.30
1900 0.15
2500 0.21
2500 0.18
3700 0.31
0.26
0.14
No. 15292000
May
3-Day Peak Flow
6070 0.43
1200 0.22 .
12000 0.62
8800 0.51
4500 0.48
1970 0.11
4300 0.31
3880 0.30
3400 0.21
7600 0.48
9000 0.52
4500 0.36
3400 0.18
900 0.21
2200 0.17
3400 0.35
1800 0.12
2230 0.14
3400 0.31
1900 0.17
1470 0.39
3030 0.14
1400 0.17
2470 0.15
2770 0.18
4600 0.36
1930 0.15
3300 0.28
2700 0.19
4100 0.34
o.za
0 .. 14
7 -Day Peak Flow
Q7 Q7/QM
8600 0961
1390 0.26
13200 0.69
8800 0.51
4500 0.48
4930 0.28
4300 0.31
4840 0.38
3400 o. 21
7600 0.48
9000 0.52
4500 0.36
3400 0.18
900 0.21
.2870 0.22
3400 0.35
2140 0.14
2340 0.14
3890 0.35
2240 0.20
1570 0~42
5930 0.27
1600 0 .. 19
3260 0.20
3540 0.23
7190 0. 57 .
2100 0.17
5610 0.47
3260 0.24
5260 0.44
0.34
0.15
14-Day Peak Flow
Q14 Q14/QM-
12200 0.87
1460 0.27
16100 0.84
12300 0.71
4500 0.48
8820 0450
5760 0.42
7130 0.55
4540 0.28
7600 0.48
12700 0.73
4500 0.36
3400 0.18
1040 0.27
4690 0.36!
3990 0 .. 41~
5010 0.32
3160 0.20
5730 0.52
5330 0.47
1820 0.49
14000 0.64
2540 0.31
5880 0.36
6170 0 .. 40
11100 0.88
3440 0.21
10300 0.86
4840 0.35
8520 0.71
0.48
0.21
susi8/b26
Comparison of L.ow Flows to Average Monthly Flow
-;
Susitna River at Gold Creek
No. 15292000
f •• ~"' VUIJIC;;
Mean Monthly 1 Day Low Flow 3-Da~ ~;ow Flow 7-Da~ Low Flow 14-0a)f Low Flow .. _
Year
Flow ~QM o, Q1/QM Q3 Q3/QM Q7 Q7/QM Q14 Q14/QM (cfs) -1950 19600 15000 0.77 15000 0.77 16300 0.83 16700 0.85 1951 20790 10600 0.51 11200 0.54 13500 0.65 16000 0 .. 77 1952 32370 21500 0~66 22700 0 .. 70 24700 0.76 27700, 0.86 1953 27320 18900 0.69 19300 0.71 21100 0.77 23700 0.87 1954 25250 21100 0~84 21600 0.86 22500 0.89 23900 0.95 1955 29860 16300 0.55 16800 0.56 18200" 0.61 24700 0.83 1956 33340 20100 0.60 21000 0 .. 63 24800 0.74 30100 0.90 1957 30160 18500 0.61 18900 0.63 20100 0.67 24700 0.82 1958 25700 19000 0.74 21000 0~82 21600 0.84 23100 0.90 1959 23320 18000 0.77 18400 o. 79· 19400 0.83 21200 0 .. 91 1960 15530 13400 0.86 13600 0.88 14400 0.93 14600 0.94 1961 294~0 1.5000 0.51 15600 0.53 17900 0.61 23400 0.79 1962 43270 27500 0 .. 64 28700 0.66 30300 0.70 38900 0.90 1963 26000 26000 1.00 26000 1.00 26000~ 1.00 26000 1.00 1964 50580 28400 0.56 30300 0.60 31000 0.61 37100 0.7~ 1965 25120 16600 0.65 18700 0.73 20500 0.80 22000 0.8{) 1966 32953 20400 0.62 22300 0.68 24300 0.74 26600 0.8~ 1967 29513 22900 0.78 25000 0.85 26600 0.90 28700 0.97 1968 31550 23000 0.73 24300 0.77 25700 0.81 29800 0.94 .. ~1'969 15503 11200 0.72 11200 0.72 11900 0.77 13500 0.87 1970 18630 14800 0.79 15000 0.81 15300 0.82 15900 0.85 1971 32930 10000 0 .. 30 10000 0.30 15700 0.48 32000 0.97 1972 34430 20400 . 0.59 20800 0.60 23300 0.68 31900 0 .. 93 1973 27800 15800 0.57 16200 0.58 17800 0.64 22600 0 .. 81 1974 17870 13600 0.76 14300 0.80 14700 0 .. 82 15900 0.89 1975 32310 22000 0.68 23700 0.73 27300 0.84 29800 0.92 1976 24380 17200 0.71 19000 0.78 19700 0.81 20700 0485 tt.={_ 1977 37970 30900 0.81 31600 0.83 33800 0.89 35900 0.95 1978 19050 12900 0.68 13400 0.70 13800 0.72 17300 0.91 1979 24690 17900 0.72. 18400 0.75 19300 0.78 21400 0.87 1980 29080 17800 0.61 19300 0.66 24600 0~85 28300 0 .. 97 #of Val. 31
Average 27970 0 .. 68 0.71 0 .. 77 0.88 $!9ndard 7740 0.13 0.13 0.11 0.06 -.jj,ev~~,---•• ---.. ., --·-------' .
----·--·-·--·----~--... ---· susi8/b27
Year
1950
1951
1952
1953
1.954
1955
1956
1957
1958
1959
1960.
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
'1979
1980
# of Val.
Average
Standard
Oev.
Mean Monthly
Flow -QM
(cfs} ·
22600
22570
26:J90
20200
20360
27560
31090
23310
22880
25000
22980
.24570
25850
34400
22950
27840
19864
26800
26922
16103
22660
23950
22770
18250
18800
27720
18940
22870
21020
28880
32660
31
24150
4240
Comparison of Low Flows to Average Monthly Flow
Susitna River at Gold Creek
No. 15292000
July
3-Day Low Flow 1 Da)! Low Flow _
Q1 Q1/QM
7-:Day Low Flow
18000
18200
17200
17200
190UO
20200
26600
18900
19000
19900
14900
23000
20900
23600
14800
20700
16200
19400
21400
11800
16500
14500
17400
14200
14900
23400
15100
18000
19400
21800
24800
0.80
0.81
0.65
0.85
0.93
0.73
0.86
0.81
0.83
0.80
0.65
0 .. 94.
0.81
0.69
0.64
0.74
0.82
0.72
0.79
0.73
0.73
0.61
0 .. 76
0.78
0.79
0.84
0.80
0 .. 79
0.92
0.75
0.76
0.78
0 .. 08
---
18700 0.83
19000 0.84
17900 0.68
17500 0.87
19000 0.93
20500 0.74
28200 0.91
19600 0.84
20300 0.89
21000 0.84
15100 0.66
23000 0.94.
21700 0.84
23900 . 0.69
15400 0.67
21200 0.76
16400 0.83
20100 0.75
23200 0.86
12500 0.78
17200 0.76
15800 0.66
17700 0.78
14500 0.79
15100 0.80
24100 0.87
-16100 0"85
18000 0.79
19800 0.94
21900 . 0.76
25300 0.77
0.80
0.08
20000
20100
19500
18100
19000
21500
29100
21200
21300
21500
16700
23000
22900
29100
16900
22100
16900
21000
24000
13900
18600
18700
18200
14900
16900
25500
17900
1.9300
20200
25300
27500
0.88
0.92
0.74
0.90
0.93
0.78
0.94
0,..91
0.93
0.86
0.73
0.94
0.89
0 .. 85
0.74
0.79
0.85
0.78
0.89
0.86
0.82
0.78
0.80
0.82
0.,90
0.92
0.95
0 .. 84
0 .. 96
0.89
0.84
0.86
0 .. 07
14-Day l.ow Flow
Q14 Q14/QM
20600 0.91
22200 0.98
22200 O~S4
19000 0.94
19000 0.93
23700 0.86
30400 0.98
22100 0.95
21600 0.94
23500 0.94
18200 0.79
23500 0.96
24800 0 .. 96
31400 0.91
19600 0.85
24700 0.89
17500 0.89
21200 0.79
24300 0.90
15600 0.97
21300 0.94
20700 0.86
19500 0.86
15800 0.87
18800 1.00
26300 0.95
18500 0.98
21600 0.94
20300 0.97
26200 0.91
. 30700 0.94
0.92
0.65
susi8/b28
Comparison of Low Flows to Average Monthly Flow
Susitna River at Gold Creek
No. 15292000
August
Mean Monthly 1 Day Low Flow 3-Day Low Flow
Year FIC~f;~M Q1 Q1/QM Q3 Q3/QM
1949 24250 15200 0.63 16100 0.66
1950 19880 11000 0.55 11300 0.57
1951 19670 15600 0.79 16300 0.83
1952 20920 13500 0.65 ~3800 0.66
1953 20610 16400 0.80 16600 0.81
1954 26100 24000 0.92 24000 0.92
1955 25750 13600 0. 53 14400 0. 56
1956 24530 18000 0. 73 18000 0. 73
1957 20540 16700 0.81 16900 0.82
1958 22540 11000 0.49 11300 0.50
1959 31180 16700 0.54 17100 0 .. 55
1960 23590 19000 0.81 19300 0.82
1961 22100 13800 0.62 . 14200 0.64
1962 23550 23000 0.98 23000 0.98
1963 23670 16500 0.70 17700 0.75
1964 16440 12000 0. 73 12300 0. 75
1965 21120 10000 0.47 10100 0.48
1966 21825 16400 0.75 16900 0.77
1967 32622 18900 0.58 19300 0.59
1968 17167 12600 0. 73 12900 0. 75
1969 8~79 5280 0. 59 5400 0. 61
1970 19980 12700 0.64 12900 0.65
1971 31910 16700 0.52 17500 0.55
1972 19290 12900 0.67 13200 0.68
1973 20290 11100 0.55 11200 0.55
1974 16220 8100 0 .. 50 3550 0.53
1975 18090 1180C· 0.65 12700 0.70
1976 19800 9340 0.47 10100 0.51
1977 19240 ·JOOOO 0 .. 52 11100 0.58
1978 16390 10400 0.63 10500 0.64
1979 20460 14000 0.68 14500 0~71
1980 20960 13900 0. 66 14500 0. 69
#of Val. 31
Average 21550 0.65 0.67
Standard 4125 0.13 0.12 ,.,V._ - -·-- . --, - - -
·: ~ . .] . ·~ . . ..... : . . . . . ' . . . ·. "'" .
7-Day Low Flow
17100 0.71
14200 0.71
17400 0.88
14500 0.69
16900 0.82
24000 0.92
17200 0.67
18000 0-73
18300 0.89
12300 0.55
18400 0.59
20700 0.88
17300 0.78
23000 0.98
20300 0.86
13700 0.83
12300 0.58
18800 0.86
21600 0.66
14000 0.82
5620 0.£3
. 14500 0. 73
20200 0.63
14700 0.76
13100 0.65
10500 0.65
14600 0.81
11900 0.60
13700 0.71
10900 0.67
15700 0.77
15000 0.72
0 .. 74
0.11 ----
14-Dai~l Low Flow
Q14 Q14/QM
17700 0.73
15900 0.80
17900 0.91
14900 0.71
17700 0.86
24000 0.92
20800 0.81
199QQ Oe81
19000 0.93
14700 0.65
20800 0.67
21700 0.92
18700 0 .. 85
23000 0.98
21900 0.93
15000 0.91
17500 0.83
20100 0.92
27400 0.84
14400 0.84
5810 0.65
17200 0.86
22400 0.70
17900 0.93
17600 0.87
13300 0.82
15900 0.88
14300 0.72
16700 0.87
13100 0.80
16700 0.82
17~00 0.84
0.83
0 .. 09 ---
-_______________________ ,_ _____ ~-=-----~-~-------
---------~--------susi8/b29
Year
1949
1950
1951
1952
1953
1954
1955
1956
1957
'k958
1959
1960
1961
1962
1.963
1964
1965
1966
1967
1968
.1969
1970 .
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
#of Val.
Average
Standard
Dev ...
Mean Monthly
Flow -QM
(cfs)
'15650
8301
21240
14480
15270
12920
14290
18330
19800
7550
16920
20510
13370
15890
12320
9511
19350
11753
16867
8815
5093
9121
14440
12400
9074
12250
16310
6881
12640
8607
10770
13280
32
13250
4190
• • "•.. • ~·. ~ ., : l. " ' .. -~ , • ' j, '
Comparison of Low Flows to Avera~e Monthly Flow
Susitna River at Gold Creek
1 Day Low Flow
Q1 Q1/QM
9160 0.59
6000 0.72
11700 0.55
9500 0.66
8880 0.58
7400 0.57
8600 0.60
14000 0.76
14200 0.72
6600 0.87
9650 0.57
13900 0.68
11500 0.86
10700 0.67
9340 0.76
7440 0.78
9280 0.48
8160 0.69
8440 0.50
5400 0.61
3710 Oo73
SOOD 0.55
8160 0.57
5500 0.44
5500 0.61
8310 0,68
10900 0 .. 67
5620 0.82
9520 0.75
4900 .0.57
8220 0.76
8890 0.67
0 .. 66
0.11
No. 15292000
September
-~3:-Dax Low Flow
Q3 Q3/QM
9400 0.60
6100 0.73
12900 0.61
9830 0.68
9430 0.62
7560 0.59
8960 0.63
14000 0 .. 76
15000. 0.76
6600 0.87
10200 0.60
14100 0.69
11600 0.87
11300 0.71
9430 0.77
7600 0.80
9380 0.48
8560 0.73
8830 0.52
5430 0.62
3760 0.74
5170 0.57
8260 0.57
5670 0.46
5670 0.62
8470 0.69
11100 0.68
5800 0.84
9750 0.7~~
5100 0.59
8510 0.79
8980 0.68
0 .. 68
0.11
7-Day Low Flow _
Q7 Q7/QM
10500 0.67
6240 0.75
15700 0.74
10300 0.71
10600 0.69
8210 0.64
9610 0.67
14000 0.76
18000 0.91
6600 0.87
10400 0. 61
15100 0.74
12100 0. 91
11900 0.75
9570 0.78
7860 0.83
13900 0.72
8830 Os75
9320 0.55
5460 0.62
3920 0.77
5290 0.58
9250 0.64
5790 0.47
6030 0.66
·goso o. 74
11600 0.71
5930 0.86
10200 0.81
5530 0.64
8720 0.81
9160 0.69
0.72
0.10
14-Dav Low Flow
Q14 Q14/QM
11600 0.74
6600 0.80
17700 0.83
11600 0.80
12300 0.81
10300 0.80
10600 0.74
17100 0.93
19400 0.98
6600 0.87
10700 0.63
17000 Q.83
13200 0.99
12100 0.76
10100 0.82
8490 0.8~
18300 0.95
10300 0.88
10700 0.63
6150 0.70
4260 0.84
7070 0.78
10100 0.70
8710 0.70
6720 0.74
9320 0.76
15400 0.94
6220 0.90
12200 0.97
6460 0.75
9330 0.87
10300 0.78
0.82
0.10
susi8/b30
Comparison of low Flows to Average Monthly Flow
Susitna River at Gold Creek
No. 15292400
October
Mean Monthly 1 Da~ Low Flow -3-Day· Low Ftow 7-Day low Flow 14-0av low Flow
Year
Flow -QM o, Q1/QM Q3 Q3/QM Q7 Q7/QM Q14 . Q14/QM (cfs)
1949 6334 3300 0.52 3400 0.54 3640 0.57 3830 0 {::.0 $G"' 1950 3848 1500 0 .. 39 1570 0~41 1810 0.47 2600 0.68 1951 5571 2900 0.52 3000 0,.54 3170 0.57 3610 0.65 1952 8202 5100 0.62 5170 0.63 5260 0.64 5490 0.67 1953 5604 2400 0.43 2540 0.45 3200 0.57 3780 0.67 1954 5370 4600 0.86 4600 0 .. 86 4600 0.86 4600 0.86 1955 4951 2800 0.57 3000 0.61 3350 0.68 3730 0.75 1956 5806 4500 0.78 4500 0.78 4500 0.78 4500 0.78 1957 8212 5400 0.66 5800 0.71 6230 0.76 7140 0.87 1958 4811 3500 0 .. 73 3500 0.73 3500 0.73 3890 0 .. 81 1959 6558 3700 0.56 3770 0 .. 57 4030 0.61 4520 0.69 1960 7794 3800 0.49 397(} 0.51 4230 0.54 4920 0.6.3 1961 5916 4600 0.78 4600 0.78 4600 0.78 4600 0.78 1962 6723 4800 0. Tl 4900 0.73 5200 0.77 5460 0 .. 81 1963 6449 3100 0.48 3270 0.51 3800 0.59 4690 0 .. 7B 1964 6291 3000 0.48 3490 0.55 3910 0.62 4400 0.70 1965 7205 2800 0.39 2930 0.41 3090 0.43 3240 0.45 1966 4162 1800 0 .. 43 1900 0.46 2100 0.50 2470 0.59 1967 4900 2900 0.59 3000 0.61 . 3140 0.64 3510 0 .. 72 1968 3822 2600 0.68 2670 0.70 2820 0.74 2940 0.77 1969. 3124 1700 0.54 1700 0.54 1810 0.58 2360 0 .. /6 1970 5288 4000 0.76 4000 0.76 4000 0.76 4210 0 .. 80 1971 5847 3600 0.62 3730 0.64 3970 0.68 4470 0 .. 76 1972 4826 3200 0.66 3400 0.70 3830 0.79 4610 0.96 1973 3733 2000 0.54 2000 0.54 2140 0.57 2440 0.65 1974 3739 1700 0.45 1700 0.45 1800 0.48 2050 0.55 1975 7739 3600 0.47 3800 0.49 4200 0.54 5420 0.70 1976 3874 3000 0.77 3000 0.77 3090 0 .. 80 3400 0.88 1977 7571 4600 0. 61 4670 0.62 5160 0.68 6040 0.80 1978 4906 2870 0.58 3190 0.65 3560 0.73 4100 0.84 1979 7311 5050 0.69 5090 0.70 5200 0 .. 71 5510 0.75 if of Val. 31
Average 5690 0.59 0.61 0.65 0.73 Standard 1450 0.13 0.12 0.11 0.11 .v .• .. .. ---------- --,. --• • • • • .. '~~ • • ... • • ,· : t-
, I . . :'. . . .. .. . ' . .... . . . • .: • • • ~ ' !'. • • • • • • • • • ' • : • • • • • I-
I
---susi8/b31 - - ----... .., - -.. -•• - -
--
I Comparison of Low Flows to Average Monthly Flow
Chulitna River n~ar Ta1keetna
No. 15292400
May
Mean Monthly 1 Day Low ~Flow 3~Da~ Low Flow -7-Day Low Flow .. _ _14-Da~ Low· F'ow _
Year
Flow -QM Q1 o 1toM Q3 Q3/QM Q7 Q7/QM . Q14 Q14/QM (cfs)
... -1958 10460 3000 0.29 3370 0.32 4250 0 .. 41 6560 0.63 1959 7413 3400 0.46 . 3400 0.46 3400 0.46 3400 0.46 1960 13890 2300 0.17 2870 0.21 3770 0.27 5940 0.43 1961 10100 2100 0.21 2630 0.26 4360 0.4S 7040 0 .. 70 1962 7743 3200 0.41 3200 0.41 3200 0.41 3200 0,41 1963 11060 2100 0.19 2100 0.19 2100 0.19 2100 0.19 1S64 2355 1400 0.59 1400 0.59-1400 0 .. 59 1430 0 .. 6.1 1965 7452 2600 0.35 .. 2600 0.35 2600 0.35 2600 0.35 1966 3971 2100 0.53 2100 0.53 2100 0.53 2100 0.53 1967 12400 1700 0.14 1970 0.16 2670 0.22 5530 0.45 1968 109.40 2000 0.18 . 2130 0.19 2440 0.22 3470 0.32 1969 6001 2600 0.43 2770 0.46 3030 0.50 3840 0.64 1970 9643 2400 0.25 2600 0.27 3090 0.32 5130 0,53 1971 4468 1200 0.27 1300 0.29 1540 0.34 2170 0.49 1972 9765 1700 0~17 2170 0.22 4070 0.42 7820 0.80 #of Val. 15
Average 8511 0.31 0.33 0.38 0.50 Standard 3270 0.15 0.13 0.12 ·0.16 Dev.
susi8/b32
Comparison of Low Flows to Average Monthly Flow
Chulitna River near· Talkeetna
No .. 15292400
June
Mean Monthly 1 Dai: Low Fiow 3 ... Da~ low Flow 7 -Day low Flow 14-Daw Low Flow
Year
F!ow -QM Q1 Q1/QM Q3 Q3/QM Q7 Q7/QM Q14 Q147QM (cfs)
1958 23170 18000 0.78 18000 0.78 18600 0 .. 80 20900 0.90
1959 23660 11000 0.46 13700 0.58 16400 0.69 17700 0.75
1960 17390 13000 0.75 13700 0. 791 14500 0.83 15500 0.89
1961 20490 10800 0.53 10800 0~53 11700 0.57 15500 0.76
1962 20620 12500 0 .. 61 12700 0.62 13200 0.64 16100 0.78
1963 17750 12200 0.69 12400 0.70 13700 0.77 13900 0 .. 78
1964 40330 37000 0.92 37000 0.92 37000 0.92 37600 0.93
1965 20070 12000 0.60 \ 14000 0 .. 70 16300 0.81 17200 0.86
1966 21740 9200 0.42 10900 0.50 17600 0.81 21200 0.98
1967 25520 16000 0.63 17700 0.69 18600 0.73 20700 0.81
1968 29d00 20600 0.71 . 21200 0.73 22200 0.77 26500 0.91
1969 18560 8580 0.46 8990 0.48 9650 0 .. 52 12000 0.65
1970 19670 14000 0.71 14300 0.73 15100 0.77 19100 0.97
1971 22180 10000 0.45 10000 0.45 11900 0.54 15600 0.70
1972 17900 11200 . 0.63 11700 0.65 12500 0.70 15400 0.86
1980 22490 15000 0.6{ 15800 0.70 19700 0.88 21700 0.96
# of Val. 16
Average 22530 0.63 0.66 0.73 0.84
Standard 5650 0.14 0.13 0.12 0.10
Dev.
'
--~--------~--~~---. .
-----------· -.. -.. ------.. -.. .. .. --susi8/b33
Comparison of Low Flows to Average Monthly Flow
Chulitna River near Talkeetna
No. 15292400
July
Mean Monthly 1 Da~ Low Flow .. 3-Da~ Low Flow 7-Da~ Low Flow 14-Day Low Flow
Year
Flow -QM Q1 Q1/QM Q3 Q3/QM Q7 Q7/QM Q14 Q14/QM (cfs)
1958 25010 19000 0.76 20200 0.81 21000 ~ 0.84 22900 0.92
1959 25650 20300 0.79 20800 0.81 21600 0.84 22100 0.86
1960 23650 17000 0.72 17300 0.73 19000 0.80 20600 0.87
1961 27420 22100 0.81 22300 0.81 23400 0.85 23900 0.87
1962 27220 25000 0.92 25000 0.92 25000 0.92 25000 0.92
1963 28950 23000 0.79 23000 0.79 23000 0.79 25400 0.88
1964 24430 21000 0.86 21000 0,.86 21000 0.86 23500 0.96
1965 23230 19800 0.85 19900 0.86 20000 0.86 22800 0.98
1966 23750 17200 0.72 17400 0.73 17600 0.74 20000 0.84
1967 35570 27600 0.78 28000 0.79 29100 0.82 30300 0 .. 85
1968 30140 23600 0.78 24900 0.83 26600 0.88 28800 0 .. 96
1969 20820 14400 0.69 15500 0.74 16200 0.78 17600 0.85
1970 26100 21000 0.80 21300 0.32 22000 0.84 23800 0.91
1971 27280 17000 0.62 18000 0.66 19000 0.70 21900 0.8~
1972 25770 19600 0.76 20200 0.78 21400 0.83 22300 0.87
1980 34948 26600 0.76 27200 0.78 28500 0 .. 82 31300 0.90
#of Val .. 16
Average 26930 0.78 0.80 0.82 0.89
Standard 3980 0.07 0.06 0.05 0.05
susi8/b34
Year
1958
1959
1960
196~1
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1980
# of Val.
Average
Standard
.•
--
Mean Monthly
Flow -Q
(cfs) M
20760
22100
19320
24580
21980
18390
20250
22550
27720
33670
20710
11300
24660
23810
20970
20784
16
22100
4690
. --
Comparison of Low Flows to Average Monthly Ffow
Chulitna River near Talkeetna
No. 15292400
August
1 Da>:: low Flow 3-Day Low Flow .. 7-Day low Flow 14-Day Low Flow o, 01/QM Q3 Q3/QM Q7 Q7/QM Q14 Q14/QM
12000 0.58 12500 0.60 13600 0.66 15500 0.75 16000 0.72 16400 0.74 17400 0.79 18900 0.86 14000 0.72 14000 0.72 14000 0.72 14000 0.72 16100 0.66 16800 0.68. 18500 0.75 22000 0.90 15800 0.72 16200 0.74 17000. 0.77 . 18200 0.83 16000 0.87 16000 0.87 16000 0.87 16900 0.92 15000 0.74 15000 0.74 17100 0.84 19400 0.96 11000 0.49 11300 0.50 12500 0.55 17300 0.77 20000 0.72 20700 0.75 23600 0.85 25100 0.91 20200 0.60 20500 0.61 22100 0.66 28700 0.85 11200 0.54 12600 0.61 14000 0.70 16800 0.81 7500 0.66 7500 0.66 7570 0.67 7650 0.68 17700 0.72 17900 0.73 18800 0.76 21900 0.89 14000 0.59 14700 0.62 16400 0.69 18200 0.7f) 12600 0.60 13200 0.63 14600 0.70 19000 o.sn 12300 0.59 12800 0.62 13500 0.65 16300 0 .. 78
0.66 0.68 0.73 0.83 0.10 0.09 0.09 0~08
----. -----.... ---
-. . . . . . . . -~ .... -. . . . . _, ......... ------susi8/b35 ___ ... _ .. __
Comparison of Low Flows to Average Monthly Flow
Chulitna River ne.ar Talkeetna
No. 15292400
September
Mean Monthly 1 Day Low Flow . 3-Day Low Flow 7-Day Low Flow 14-Day !iJow Flow ---
Year
Flow -QM o, Q1/QM Q3 Q3/QM Q7 Q7/QM Q14 Q14/QM
(cfs)
1958 8000 6800 0.85 6800 0.85 6800 0.85 6800 0.85
1959 9957 6800 0.68 7000 0.70 7210 0.72 7460 0.75
1960 12420 7400 0.60 7470 0 •. 60 7780 0.63 10700 0.86
1961 16030 9680 0.60 9990 0.62 11300 0 .. 70 12900 0.80
1962 13490 8130 0.60 8170 0.61 8440 0.63 8990 0.67
1963 11330 10000 0.88 10000 0.88 10000 0.88 10000 0.88
1964 9235 6220 0.67 6850 0.74 7120 0.77 7380 0.80
.1965 22260 10700 0.48 . 10700 0.48 17600 0.79 19900 0.89
1966 12200 . 8480 0 .. 70 8660 0.71 9000 0.74 10500 0.86
1967 12510 6000 0 .. 48 6400 0.51 7300 0.58 8760 0.70
1968 7375 4150 0.56 4260 0.58 4570 0.62 5360 0.73
1969 6704 4320 0.64 4410 0.66 4800 0.72 5350 0.80
1970 11330 5000 0 .. 44 5000 0.44 5290 0.47 7040 0.62
1971 11080 6000 0.54 6170 0.50 6470 0.58 7540 0.68
1972 12120 6000 0.50 6090 0.50 6330 0.52 7470 0.62
1980 8240 6080 0.74 6270 0.76 6540 0.79 7690 0 .. 93
' # of Val. 16
Average 11520 ·0.62 Q.64 0.69 0.78
Standard 3770 0.13 0.13 0.12 0.10
Dev.
. .
susi8/b36
Comparison of Low Flows to Average Monthly Flow
Chulitna River near Talkeetna
No. 15292400
October
Mean Monthly 1 Da~ Low Flow 3-Da~ Low Flow 7-Da~ Low Flow 14-Da~ Low Flow
Year
Flow -QM Q1 Ql/QM Q3 Q3/QM Q7 Q7/QM 0 14 Q14/QM
(cfs)
1958 4197 2910 0.69 2940 0.70 3060 0.73 3290 0.78
1959 4723 3000 0.64 3070 0.65 3230 0.68 3500 0.74
1960 5135 2500 0.49 2600 0.51 2760 0.54 3130 0.62
1961 5777 3100 0.54 3270 0.57 ,3400 0.59 3850 0.67
1962 3506 1700 0.48 1800 0.51 1870 0.53 1940 0.55
1963 8062 4800 0.60 4800 0.60 4800 0.60 5590 0.69
1964 5642 3300 0.58 3330 0.59 3410 0.60 3690 0.65
1965 6071 2950 0.49 2950 0.49 2950 0.49 2950 0.49
1966 4682 2000 0.43 2000 0.43 2170 0.46 2630 0.56
1967 3483 1900 0.55 1930 0.55 2040 0.59 2390 0.69
1968 2898 1900 0.66 2000 0.69 2190 0.76 2330 0.80
1969 4578 3000 0.66 3000 0.66 3030 0.66 3170 0.75
1970 3826 3000 0.78 3000 0.78 3030 0.79 3170 0.83
1971 5439 2900 0.53 3000 0.55 3170 0.58 3700 0.68
# of Val. 14
Average 4858 0.58 0.59 0. 61 0.68
Standard 1324 0.10 0.10 0.10 0.10
Dev.
J .I J . .J
·'
-· --.. -... -.. - - ----.... - - -susi8/b37
Mean Monthly
Year
Flow -QM
(cfs)
. 1965 3474
1966 2410
1967 4112
1968 8840
1969 3869
1970 395{)
1971 2145
1972 . 3516
1973 3860
1974 5678
'1975 4084
1976 3439
1977 4244
1978 2950
1979 7790
1980 4820
# of Val. 16
Average 4324
Standard 1732
Dev.
.
.. iliiiiliiiliiflii.ii'~··-·· ···lliioii"'' ~~iiilioi"'"h• ...... .o••.o.,.~-~·r-•~·'''"''-'·:..t:::'.__.._'L_··o,,, .. _.,..,., .
Comparison of Low Flows to Average Monthly Flows
Talkeetna River near Talkeetna
No. 15292700
May
1 Day Low Flow . 3-Day Low Flow 7-Da~ Low Flow 14-Day Lo\.Y Flow
Q1 Q1/QM Q3 Q3/QM Q7 Q7/QM. Q14 Q14/QM
960 0.28 960 0.28 960 0.28 1100 0.32
540 Oac22 577 0.24 687 0.29 1060 0.44 .
550 0.13 617 0.15 900 0.22 1860 0.45
1650 0.19 1750 0.20 2050 0.23 3000 0.34
1000 0.26 1100 0 .. 28 1300 0.34 1750 0.45
800 0.20 850 0.22 1010 0.26 2030 0.51
650 0.30 683 0.32 743 0.35 932 0.43
BOO 0.23 . 850 0.24 971 0~28 12!JO 0.37
850 0.22 900 0.,23 1010 0.26 1500 0.39
900 0.16 1000 0.18 1240 0.22 2010 0.35
600 0.15 633 0.15 693 0.17 936 0.23
1300 0.38 1500 0.44 2200 0.64 3030 0.88
660 0 .. 16 673. 0.16 739 0.17 1340 0.31
700 0.24 723 0.25 813 0.28 1810 0.6
1800 0.23 2070 0.27 2760 0.35 3790 0.49
2100 0.44 2200 0.46 2410 0.50 2900 0.60
0.24 0.25 0.30 0.45
0.08 0.09 0.12 0.15
-----·--· ------~--
susi8/b38
Comparison of Low Flows to Average Monthly Flows
Talkeetna River near Talkeetna
No. 15292700
June
Mean Monthly 1 Da~ Low Flow .. 3-Da~ low Flow 7-Day: Low Flow
'
14-Da~ Low Flow
Flow ·QM Q1 o,;oM Q3 Q3/QM Q7 Q7/QM Q14 Q14/QM Year (cfs) -
1964 17080 11000 0.64 . 11300 0.66 12300 0.72 13500 0.79
1965 11090 7120 0.64 7460 0.67 8700 0.78 9560 0.86
1966 12970 6420 0.49 7990 . 0.62 9130 0.70 9940 0.77
1967 9286 6200 0.67 6370 0.69 6660 0.72 7400 0.80
1968 14100 9500 0.67 9830 0.70 10600 0.75 12600 0.89
1969 5207 3440 0.66 3540 0.68 3730 0.72 4400 0.85
1970 7979 4700 0.59 5040 0.63 5700 0.71 6830 0.86
1971 19040 4750 0.25 4880 0.26 8450 0.44 16300 0.86
1972 12700 8560 0.67 8730 0.69 9030 0.71 10900 0.86
1973 12210 6260 0.51 6720 0.55 7630 0.62 9260 0.76
1974 8030 5200 0.65 5810 0.72 6470 0.81 7330 0.91
1975 13180 8810 0.67 9500 0.72 10500 0.80 11700 o.8g
1976 10580 6040 0.57 7480 0.71 7640 0.72 8820 0.83
1977 18280 13300 0.73 13900 0.76 14200 0.78 15700 0.86
1978 7429 4540 0.61 4800 0.65 5660 0.76 7080 0.95
1979 12010 7090 0.59 7390 0.62 7710 0.64 9300 0.77
1980 11380 8000 0.70 8330 0.73 10400 0.91 10900 0.96
# of Val. 17
Average 11910 0.61 0.65 0.72 0.85
Standard 3800 0.11 0.11 0.10 0.06
Dev.
------------- ------susi8/b39
Comparison of Low Flows to Average Monthly Flows
Talkeetna River near Talkeetna
No. 15292700
July
Mean Monthly 1 Da~ Low Flow 3-Da~ Low Flow 7-Da~ Low Flow 14-Day l.ow Flow
Year
Flow -QM Q1 Q1/QM Q3 Q3/QM Q7 Q7/QM Q14 Q14/QM (cfs)
1964 9820 7810 0.80 8190 0.83 8420 0.86 9310 0 .. 95
1965 12180 8400 0.69 8490 0.70 9050 0.74 10600 0 .. 87
1966 10100 5870 0.58 6220 0.62. 6510 0.64 8640 0.86
1967 12600 8600 0.68 8800 0~70 8980 0.71 9370 0.74
1968 11230 9000 0.80 9000 0.80 9410 0.84 9770 0.87
1969 7080 5300 0.75 5680 0.80 6050 0.85 6840 0.97
1970 10320 7300 0.71 7690 0.75 8150 0.79 9110 0.88
1971 11760 7000 0.60 ' 7670 0.65 8710 0.74 9750 0.83
1972 12030 9800 0.81 9880 0.82 10400 0.86 11300 0.94
1973 7676 5800 0.76 5870 0.76 6140 0 .. 80 6700 0 .. 87
1974 7755 6440 0.83 . 6560 ·o .. as 6960 0.90 7220 0 .. 93
1975 12070 8690 0.72 8940 0.74 9560 0.79 10600 0.88
1976 9026 6310 0.70 6620 0.73 7380 0.82 8440 0 .. 94
1977 9344 7310 0.78 7350 0.79 7630 0.82 8580 0 .. 92
1978 10790 8110 0.75 8610 0.80 10200 0.95 10200 0.95
1979 14440 9180 0.64 9550 0.66 11900 0.82 12300 0.85
1980 13900 10000 0.72 10100 0.73 10800 0.78 13000 0.97
#ofVal. 17
Average 10710 0.72 0.75 0.81 0.90
Standard 2120 0.07 0.07 0.07 0.06
Dev.
.. .]
. . . : . .. -. . ·:. . ... . . . .: : .... · .. ·. .. . . ...... •. . . . '. . .:
susi8/b40
Comparison of Low Flows to Average Monthly Flows
T'11 keetna Rive·r near Talkeetna
No. 15292700
August
Mean Monthly 1 Day Low Flow 3-Da~ Low Ffow 7-Day Low Flow 14-Da~ Low Flow
Year
FJow -QM . Q1 Q1/QM Q3 Q3/QM Q7 07/Qw, Q14 Q14/QM (cfs)
1984 8396 5300. 0.63 5430 0.65 6140 0.73 7100 0.85 1965 11150 5300 0.48 5570 0.50 6560 0.59 9280 0.83 1966 10730 7520 0.70 7650 0.71 8070 0.75 9010 0.84 1967 14160 8550 0.60 8720 0.62 9750 0.69 13000 0.92 1968 7546 5720 0.76 5960 0.79 6530 0.87 7110 0.94 1969 3787 2100 0.55 2110 0.56 217() 0.57 2230 0.59 1970 8752 6000 0.69 6220 0.71 6870 0.78 7800 0 .. 89 1971 16770 7500 0.45 7670 0 .. 46 8430 0.50 9570 0.57 1972 9576 6400 0.67 6500 0.68 6970 0.73 8380 0 .. 88 1973 9927 5220 0.53 5330 0.54 5910 0.60 7680 0.77 1974 7704 3680 -0.48 ' 3940 Oa51 4760 0.62 6200 0.80 1975 8487 . 4920 0.58 5130 0.60 5980 0.70 7020 0.83 1976 8088. 4190 0.52 4370 0.54 5170 0.64 6480 0.80 1977 8005 4780 0.60 4840 0.60 5560 0.69 7360 0.92 1978 7001 3890 0 .. 56 4100 0.59 4390 0.63 5160 0.74 1979 8274 4580 0.55' 5180 0.~63 6140 0.74 6530 0.79 1980 7220 4320 0.60 4530 0.63 4780 0.66 5960 0.83 # of Val. 17
Average 9151 0.59 0.61 0.68 0~81 Standard 2922 0.08 0 .. 09 0.09 0.10 Dey~-
-·-. . ' ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~·~~-M~ ~~-~~··•-·~~~••··~-·-"·'-~::,. --~~-~-·-~a •. ~y······~•~w~.~ - - - -.. - -··--.• - -'--.. --.....
I J : J -) --J ~ ] ] } l l J _]-.
susi8/b41
I Comparison of Low Flows to Average Monthly Flows
Talkeetna River near Talkeetna
I
No. 15292700
September
Mean Monthly 1 Da~ Low Flow 3-Da~ Low Flow 7-Da~ Low Flow 14-Da~ Low Flow
Flow -QAJI Q1 0/QM Q3 Q3/QM Q7 Q7/QM Q14 Q14/QM
Year (cfs) '
1964 3815 3080 0.81 3160 0.83 3230 0.85 3410 0.89
1965 10670 5100 0.48 5130 0.48 6560 0.62 8170 0.77
1966 5370 3500 0.65 3600 0.67 3980 0.74 4600 0.86
1967 6971 3140 0.45 3280 0.47 3540 0. 51 4200 0.60
1968 4120 2500 0.61 2530 0.61 2610 0.63 2890 0.70
1969 2070 1700 0.82 1700 0.82 1700 0.82 1730 0.84
1970 5993 3530 0.59' 3600 0.60 3680 0.61 4750 0.79
1971 5990 3400 0.57 3470 0.58 3770 0.63 4090 0.68
1972 8709 4600 0.53 4700 0.54 5110 0.59 6210 0.71
1973 3861 2420 0.63 ·2480 0.64 2610 0.68 2860 0.74
1974 4763 . 2860 0.60 2930 0.62 3280 0.69 3570 0.75
1975 7960 4720 0.59 4830 0.61 5700 0.72 7740 0.97
1976 3205 2600 0.81 2700 0.84 2910 0. 91 3100 0.97
1977 5826 3820 0.66 4030 0.69 4200 0.72 4960 0.85
1978 3513 2200 0.63 2300 0.65 2500 0.71 2760 0.78
1979 4039 3220 0.80 3230 0.80 3280 0.81 3400 0.84
1980 5400 2700 0.50 2730 0.51 2900 0.54 3470 0.64
# of Val. 17
Average 5428 0.63 0.64 0.69 0.79
Standard 2192 0.12 0.12 0.11 0.11
Dev.
susi8/b42
Comparison of Low Flows· to Average Monthly Flows
Talkeetna River near Taikeetna
No. 15292700
October
Mean Monthly 1 Day Low Flow 3-Da~ Low Flow 7-Da~ Low Flow 14_-Day Low Flow
Year
Flow -QM Q1 Q1/QM Q3 93/QM Q7 Q7/QM Q14 Q14/QM
~cfs)
1964 31.15 1910 0.61 2030 0 .. 65 2170 0.70 2340 0 ... 75
1965 4438 2150 0.48 2220 0.50 2410 0.54 2770 0,62
1966 2388 1100 0 .. 46 1170 0.49 1270 0.53 1510 0.63
1967 2029 1500 0.74 1500 0.74 1540 0.76 1610 0.79
1968 1637 1200 0.73 1200 0.73 1240 0.76 1340 0.82
1969 1450. 1100 0.76 1100 0.76. 1100 0.76 1150 o. 77
1970 2817 2000 0.71 2000 0.71 2000 0.71 2170 0.77
1971 2632 1800 0.68 1830 0.69 1910 0.73 2130° 0.81
1972 3630 2000 0.55 2130 0.59 2400 0.66 3020 0.83
1973 1807 1200 0.66 1200 0.66 1260 0.67 1360 0.75
1974 1967 1200 0.61 1200 0.61 1390 0.71 1450 0.74
1975 2884 1200 0.42 1230 0.43 1330 0.46 1710 0.59
1976 1857 1400 0.75 1470 rt ""7n 1530 0.82 1SSO 0.90 v. I ::I
1977 3268 1600 0.49 1700 0.52 1900 0.58 2360 0 .. 7Z
r
1978 1660 1120. 0.67 1280 0 .. 77 1380 0.83 1450 0.81
1979 3370 2200 0.65 2250 0.67 2300 0.68 2430 0.72
# of Val. 16
Average 2559 0.62 {).64 0.68 0.76
Standard 854 0.11 . 0.11 0.11 0.09
Dev.
ll -------------------
It-~
! ---susi8/b43
Mean Monthly
Year
Flow -QM
(cfs)
1975 47540
1976 70460
1977 t;S180
1978 48670
1979 81260
1980 66580
# of Val. 6
Average 61780
Standard 13295
Dev.
----------
Comparison of Low Flows to Average Monthly Flows
Susitna River· at Susitna Station
No. 15294350
May
--
1 Day Low Flow 3-Day Low flow 7-Day Low Flow -Q1 0 1/QM Q3 Qg/QM Q7 Q7/QM
-
9000 0.19 9330 0.20 10100 0.21
"30000 0 .. 43 41300 0 .. 59 62700 0.89
7500 0.13 8000 0 .. 14 9500 0.17
11000 0.23 12300 0.25 17600 0.36
18000 0.22 21000 0.26 32600 0 .. 40
20000 0 .. 30 22700 0.34 31300 0.47
0.25 0.30 0.42
0.10 0.16 0.26
J
---
14-Day :Lo\v Flo~
Q14 Q14/QM
14100 0.30
63000 0.89
19000 0.34
36700 0.75
55000 0.68
46600 0.70
0 .. 61
0 .. 24
susi8/b44
Mean Monthly
Year
Flow -QM
(cfs)
1975 128800
1976 107000
1977 165900
1978 90930
1979 119900
1980 142900
#of Val. 6
Average 125900
Standard 26510
Oev.
-
Comparison of Low Flows to Average Monthly Flows
Susitna River ·at Susitna Station
No. 15294350
June.
1 Day Low Flow 3-Day Low Flow 7-Day Low FIQ!_v.._.. -Q1 Q1/QM Q 3 Q3/QM Q .. 7 Q7/QM
102000 0.79 106000 0.82 110000 0.85
61800 0.58 69300 0.65 84500 0.79
130000 0.78 143000 O.BS t55000 0.93
62800 0.69 65700 0.72 66300 0.73
99000 0 .. 83 101000 0.84 10300() 0.86
110000 0.77 . 113000 0 ,..19 , " 126000 0.88
0.74 0 .. 78 0.84
0.:09 0.08 0.07
-.. -- -
---.
14-Dav LOW F~ow -· --·:-~!.~~:.v.JQ ,_
Q14 '"{14 M
_.,:;~~
·118000 0.92
97900 0~91'
158000 0.95
76900 0 .. 85
111000 0.93
138000 0.97
0.92
0.04
---
~---~-------~~~~------------·~------~-------~---.~~.·---··~----------------------------~~--------~ --· -·--.. -£USi8/b45 --.... · -· .. ---
Comparison of Low flows to Average Monthly Flows
Susitna River at Susitn.a Station
No. ~15294350
July
-
Mean Monthly 1 Da~ low Flo~ 3-Da~ Low Flow 7-Da~ Low FJow
Ffow -QM Q1 Q1/QM Q3/QM Year (cfs) Q3 Q7 Q7/QM
1975 135700 108000 0.80 113000 0.83 114000 0.84 1976 115200 93400 0.81 95400 0.83 100000 0.87
1977 143900 124000 0 .. 86 127000 0.88 134000 0.93 1978 117600 106000 0.90 109000 0 .. 93 115000 0.98 1979 142500 110000 0.77 111000 0.78 129000 0 .. 91
1980 181400 145000 0.80 148000 0.82 160000 0.88 # of-Val. s
Average 139380 0.82 0.85 0.90
Stanclard 23950 0.05 0.05 0.05 Dev.
----
14-DaY: Low Flow
Q1~· Q14/QM
121000 0.89
107000 0.93
141000 0.98
117000 0.99
133000 0.93
176000 0.97
0.95
0 .. 04
J
\
susi8/b46
Year
1975
1976
1977
1978
1979
1980
# of Val.
Average
Standard
Oev .
Mean Monthly
Flow -QM
(cfs)
91360
99650
125500
102100
128200
126400
6
112200
16300
Comparison of Low Flows to Average Monthly Flows
Susitna River at Susitna Station
No. 15294350
August
1 Day Low Flow 3-Day Low Flow 7-Day Low. Flow
57600 0.63 63600 0.70 71200 0.78
56800 0.57 61700 0.62 71900 0.72
76200 0.61 80900 0.64 96600 . 0.77
65400 0.65 68400 0.67 72500 0.71
78900 0.62 88800 0.69 99900 0. 78
92000 0.73 95300. 0.75 103000 0.81
0
0.64 0.68 0.76
0 .. 05 0.05 0.04
14-Day Low Flow
80000 0.88
82800 0.83
116000 0.92
83600 0.82
" :116000 0.90
111000 0.88
0.87
0.04
... -----.. ~ ... -------
__ .. _____________ _ susi8/b47
Mean Monthly
Flow -Q
Year (cfs) M
1975 77740
1976 48910
1977 83810
1978 55500
1979 74340
1980 91200
#of Val. 6
Average· 71910
Standard 16440
Dev.
Comparison of Low Flows to Average Monthly Flows
Susitna River· at S.usitna Station
No. 15294350
September
1 Day L 'tJW Flow 3-Day Low Flow 7-Day Low Flow 14-Day Low Flow
47800 0.61 48000 0.62
37000 0.76 37300 0 .. 76
59200 0.71 64000 0.76
29000 0.52 30000 0.54
51800 0 .. 70 52200 0.70
80000 0.88 80700 0.88
0.70 • 0.71
o:.12 0.12
57700
38600
69400
32100
53100
81100
-----
0.74 73700
0 .. 79 39200
0.83 81200
0.58 40100
0.71 56900
0.89 83700
0.76
0.11
0.95
0.80
0 .. 97
0 '72 ....
O.,il
0.92
0.86
0 .. 10
I
I ,,
I
"I l:
-----------------------------
susi8/b48
Comparison of Low Flow and Average Monthly Flows
Susitna River at Susitna Station
No. 15294350
October
Mean Monthly 1 Da~ Low Flow 3-Da~ Low Flow 7-Da:l Low Flow 14-Da~ Low Flow
Year
Flow -QM Q1 Q1/QM Q3 Q3/QM Q7 Q7/QM Q14 Q14/QM
II . (cfs)
1974 19520 11000 0.56 11300 0.58 12100 0.62 13600 0.70
1975 31550 16000 0.51 17300 0.55 18900 0.60 22700 0.72
1976 30140 23000 0.76 24000 0.80 26400 0.88 29300 0.97
1977 38230 19000 0.50 19700 0.52 21300 0.56 24800 0.65
1978 36810 26000 o. 71 26700 0.73 30000 0.81 35100 0.95
1979 58640 33800 0.58 34200 0.58 36100 0.62 . 41400 0.71
# of Val. 6
Average 35815 0.60 0.63 0.68 0.78
Standard 12990 0.11 0.11 0.13 0.14
Dev.
J
"~ .. --- --" - - - - - -.., - --- -••.
susi8/f1
Comparison of Annual Low Daily Flows to Annual
Low Monthly Flow
Susitna River near Cantwell
Station Number 15291500
1-Da)!: Low Fiow 3-Day Low Flow 7-Day ~w "Flow 14-Day Low Flow 30-Day low Flow SO-Day Low Flow 90-Day Low f!~
Year Q1 Q1/Qm Q3 Q3/Qm Q1 Q7/Qm Q14 Q1iQm Q30 Q307Qm Q60
___ ,
Q6o 1Qm Q9o 09ol~rn
------
1962 940 1.00 940 1.00 940 1.00 940 1.00 940 1.00 972 1.03 1050 1.1'~
1963 720 1.00 720 1 .• 00 720 . 1.00 720 1.00 740 1.00 740 1.03 777 1.Q~
1964 400 0.93 400 0.93 400 0.93 400 0.93 419 0.98 445 '1,04 488 1 .. 1l4t
1965 680 1.00 680 1.00 sao 1.00 680 1.00 681 1.00 694 1.02 718 1.QS
1966 650 1.00 650 1.00 650 1.00 650 1.00 650 1.00 651 1.00 667 LOS
1967 500 0.97 500 0~97 500 0.97 500 0.97• 510 0.99 536 1.04 571 1. ·n
1968 1200 1.00 1200 1..00 1200 1.00 1200 1.00 1200 1.00 1200 1.00 1200 1.C.C
1969 480 0.99 480 tt.99 480 0.99 480 0.99 484 1.00 492 1.01 511 1.0$
1970 420 0.99 420 0.99 420. 0.99 420 0.99 420 0.99 428 1.00 442 1 .. ~
~971 460 0.98 460 0.98 460 0.98 460 0.98 465 0.99 474 1.01 500 1.00
1972 850 0.97 850 0.97 850 0.97 850 0.97 850 0.97 873 1.00 892 1.<W
Average 0.98 0.98 0.98. 0.98 0.99 1.02 1~00
Standard 0.02 0.02 0.02 0.02 0.01 0.02 .0Jl4
Dev.
,,
susi8/f2
Comparison of Annual low Daily Flows to Annual
Low Monthly Flow
Susitna River at Gold Creek
Station Number 1529200
1-Da't Low Flow 3-Da't Low Flow 7-Da't low Flow 14-Da't Low Flow 30-Da't low Flow 60-Da't low Flow 90-Da't Low Flow
Year 01· 0/0m 03 0/0m 07 0/0m 014 0 1/0m 030 03o10m 05o 06o/Om 09o 090/Qm
1950 600 0.76 600 0.76 614 0.78 648 0.82 674 0.93 716 0.99 797 1.10
1951 740 1.00 740 1.00 740 1.00 740 1.00 740 1.00 772 1.04 823 1 . 11
1952 880 1.00 880 1.00 880 1.00 880 1.00 880 1.00 899 1.02 932 1.06
1953 820 1.00 820 1.00 . 820 1.00 820 1.00 820 1.00 822 1.00 888 1.08
1954 780 1.00 780 1.00 780 1.00 780 1.00 780 1.00 854 1.09 956 1.23
1955 1100 1.00 1100 1.00 .1100 1.00 1100 1.00 1100 1.00 1150 1.05 1230 1.12
1956 940 1.00 940 1.00 940 1.00 940 1.00 940 1.00 945 1. 01 953 1.01
1957 1200 1.00 1200 1.00 1200 1.00 1200 1.00 1200 1.00 1200 1.00 1300 1.08
1958 1100 0.96 1100 0.96 1100 0.96 1100 0.96 1140 0.99 1200 1.05 1280 1.11
1959 980 1.00 980 1.00 980 1.00 980 1.00 980 1.00 1040 1.06 1160 1.18
1960 1100 0.92 1100 0.92 1100 0.92 1100 0.92 1100 0.92 1220 1.02 1310 1.09
1961 1500 0.83 1500 0.83 1500 0.83 1500 0.83 1610 0.92 1800 1.03 2010 1.15
1962 1400 1.00 1400 1.00 1400 1.00 1400 1.00 1400 1.00 1450 1.04 1540 1.10
1963 830 1.00 830 1.00 830 1.00 830 1.00 830 1.00 915 1.10 1110 1.34
1964 660 0.93 660 0.93 660 0.93 660 0.93 683 0.96 728 1.02 794 1.11
1965 860 1.00 860 1.00 860 1.00 860 1.00 863 1.00 882 1.03 908 1.06
1966 1300 1.00 1300 1.00 1300 1.00 1300 1.00 1300 1.00 1300 1.00 1330 1.02
1967 1100 0.94 1100 0.94 1100 0.94 1100 0.94 1130 0.97 1180 1.01 1250 1.07
1968 1800 0.94 1800 0.94 1800 0.94 1830 0.96 1870 0.98 1880 0.99 1890 0.99
1969 700 0.97 700 0.97 700 0.97 700 0.97 700 0.97 723 1.00 750 1.04
1970 750 0.98 750 0.98 750 0.98 750 0.98 750 0.98 773 1. 01 790 1.03
1971 950 1.00 950 1.00 950 1.00 950 1.00 950 1.00 970 1.02 1020 1.07
1972 1600 0.94 1600 0.94 1600 0.94 1640 0.96 1680 0.98 1760 1.03 1850 1.08
1973 1000 1.00 1000 1.00 1000 1.00 1000 1.00 1000 1.00 1010 1.01 1070 1.07
197·1 700 0.97 700 0.97 700 0.97 700 0.97 707 0.97 730 1.01 762 1.05
1975 "1400 1.00 1400 1.00 1400 1.00 1400 1:00 1400 1.00 1410 1.01 1440 1.03
1976 900 1.00 900 1.00 900 1.00 900 1.00 900 1.00 916 1.02 928 1.03
1977 1500 1.00 1500 1.00 1500 1.00 1500 1.00 1500 1.00 1550 1.03 1590 1.06
1978 1600 1.00 1600 1.00 1600 1.00 1600 1.00 1600 1.00 1620 1.01 1650 1.03
1979 1200 1.00 1200 1.00 1200 1.00 1200 1.00 1200 1.00 1230 1.03 1260 1.05
1980 1400 1.00 1400 1.00 1400 1.00 1400 1.00 1400 1.00 1400 1.00 1450 1.04
Average 0.97 0.97 0,97 0.98 0.99 1.02 1.08
Standard 0.05 0.05. 0.05 0.05 0.02 ·o.o3 0.07
Dev .
!'·-·--·· . J .J ... J .J J .,.J .J c ... J .I .I ... J
·"
-------------------
susi8/f3
Comparison of Annual Low Daily Flows to Annual
Low Monthly Flow
Chulitna River near lalkeetna
Station Number 15292400
J -Oa~ Low Flow 3-Day: Low Flow 7 .. Qay: Low Flow 14-Da}!_ Low Flow 30-Day: Low F!ow GO-Day: Low Flow 90-Day: tt..~· .f!~
Year Q Q1/Qm Q3 Q3/Qm Q7 Q7/Qm Q14 01iQm Q30 Q3o10m 05o Oso/Qm 0 9o ~$0/Qm 1 , --
1959 690 0.93 690 0.93 690 0.93 690 0.93 732 0.99 808 'L09 888 ~ .. 20
1960 880 0.94 880 0.94 880 0.94 880 . 0~94 889 0.95 941 1.01 1010 t;()S
1961 950 0.88 -350 0.88 950 0.88 950 0.88 1030 0.95 1100 1.02 1210 '. 12
1962 930 1.00 930 1.00 930 1.00 930 1.00 930 1.00 949 1.02 1020 1.1()
1963 650 0.93 650 0.93 650 0.93 650 0.93 690 0.99 771 1.10 947 l .. 35
. 1964 770 1.00 77Q 1.00 770 1.00 770 1.00 770 1.00 794 1.03 842 l-.09
1965 1300 1.00 1300 1.00 1300 1.00 1300 1.0CJ '1300 1.00 1350 1.04 1370 '\,05
1966 1100 1.00 1100 1.00 1100 1.00 1100 1.00 1100 1.00 1100 1 .. 00 11;\0 1 .. 03
1967 900 0.93 900 0.93 • 900 0.93 900 0.93 928 0.95 999 1.03 1090 1.12·
1968 1100 0.96 1100 0.96 1100 0.96 1100 0.96 1140 0.99 1170 1.02 1180 l .. OS
1969 800 0.97 800 0.97 800 0.97 800 0.97 823 1.00 857 1.04 885 1~07
1970 '1100 1.00 1100 1.00 1100 1.00 110} 1.00 1100 1.00 1120 1.02 1150 t .. OS
1971. 900 0.96 900 0.96 900 0.96 B14 0.$8 933 1.00 942 1.01 953. 1;02
1972 850 0.95 850 0.95 850 0.95 850 0.95 868 0.97 908 L02 954 1 .. 07
AVerage , 0.96 0.96 0.96 0.96 0.99 1.03 1 .. 10
Standard 0.04 0.04 0.04 0.04 0.02 0.03 \},09
Dev,
1_/
sus!8/f4
Comparison of Annual Low Daily Flows to ~nnual
Low Monthly Flow
Talkeetna F{ivet~ near Talkeetna
Station Number 15292700
1-Da~ Low Flow
. 11 ~:f>l!Y Low FiQ.W 7-Da~ low., Flow 14-Da~ Low Flow 30-Day Low Flow 60-Da~ Low .Flow 90-Day Low fli~w
Year o, Q1/Qm Q3 Q:/Om Q7 Q7/Qm Q14 o,iQm :Q30 %o 10m Q60 Q6o/Qm 09o 09Q7~·m -----
1965 540 1.00 540 1.00 540 1. ~iO 540 1.00 540 1.00 559 1.04 580 1-([?
1966 390 ~0.99 390 0.99 390 0.99 390 0.99 393 0.99 405 1.C3 446 1~t3s
1967 420 ·o.98 420 0.98 420 0.98 420 0.98 425 1.00 448 1.05 481 1.t3;
1968 740 1.00 740 1.00 740 1.00 740 1.00 741 1.00 754 1.01 774 1 .,a:4{
1969 380 1.00 380 1,00 380 1.00 380 1w00 380 1.00 384 1.01 398 1~0.$.
1970 440 1.00 440 1.00 440 1.00 440 1.00 440 1.00 444 1.0i 456 1.Q'rt
1971 400 1.00 400 1.00 400 1.00 400 1.00 400 1.00 420 1.04 448 1.1111
1972 400 0.77 400 0.77 400 0.77 411 0.79 434 0.84 481 1.00 539 1.11~
1973 500 0.87 500 0.87 500 0.87 514 0.89 533 0.92 566 0.99 59~ 1~~
1974 450 0.93 450 0.93 450 0.93 450 0.93 458 0.95 485 1.01 516 l .. Qif
1975 500 0.98 500 0.98 500 0.98 50\J 0.98 500 0.98 512 1.01 538 1..00
1976 460 0.98 460 o.qa 460 0.98 460 0.98 463 0.99 471 1.00 479 1.~
1077 500 0.99 500 o.g9 500 0.99 500 0.99 505 1.00 516 1.02 534 1~00
1Q78 460 0.95 460 0.95 461 0.95 466 0.96 473 0.98 497 1.02 531 1.69
1979 540 0.94 540 0.94 540 0.94 541 0.94 548 0.95 576 1.00 611 l.EJS
19SO 700 1.00 700 1.00 700 1.00 700 1.00 700 1.00 713 1.02 742 1.00
Average 0.96 0.96 0.96 0.96 0.98 1.02 1.017
Standard 0.06 0.06 0.06 0.06 0.04 0.02 O.Ol
O&V.
- - - -·--- - ------ -.. ----,--
~--.. -------------..... -
susi8/f5
Comparison of Annual Low Daily Flows to Ann~al
Low Monthly Flow
Susitna River at Susitna Station
Station Number 15294350
1-Day Low Flow 3-Day Low Flow 7-Day .Low Flow 14-Day Low Flow 30-Day Low Flow 60-Day Low Fiow 90-Day Low Ft~w
$ -...,. Year o, 0 1/Qm Q3 Q3/Qm Q7 Q7/Qm Q14 Q14/Qm Q30 Q30/Qm Q60 Oeo 10m 09o OoolQ~
()
1975 6500 0~95 6500 0.95 6500 0.95 6500 0.95 6720 0.98 6920 1.01 7230 1.05
1976 5200 0.97 5200 0.97 5200 ' 0.97 5200 0.97 5310 0.99 5370 1.00 5580 1.04
1977 6000 0.96 6000 0.96 6000 0.96 .6000 0.96 6180 0.99 6490 1.04 7220 1.1&
1978 6400 0.91 6400 0.91 6400 0.91 6430 0.91 6520 0.99 6590 1.00 6680 1.01
1979 ° 6500 0.75 6500 0.75 -6500 0.75. 6640 0.76 6830 0.97 7100 1.01 7500 1.01
1980 8600 0.97 8630 0.97 8700 0.98 8800 0.99 8870 1.00 8960 1,01 9210 1~·U3
AVerage 0.92 0.92 \ 0.92 0.92 0.99 1.10 1.0&
Standard 0.09 0.09 0.09 0.08 0.01 0.01 O.GS
APPENDIX C
WATER SURFACE ELEVATIONS
r29/g3
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