HomeMy WebLinkAboutAPA24151983-1984
SUSITNA RIVER ICE STUDY
DRAFT REPORT
JUNE 1984
SUSITNA
HYDROELECTRIC PROJECT
R&M CCNSULTANTS.INC•
•"'GIN8._CI.O~ClI.?W .....AHN.....",.-V.YO••
/Jl1UlU.~
SUSITNA JOINT VENTURE
PREPARED BY .
UNDER CONTRACT TO
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",-_ALASKA POWER AUTHORITY_--J
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SUSITNA HYDROELECTRIC PROJECT
SUS ITNA RIVER I CE STUDY
1983-1984
Report by :
R&M CONSULTANTS ,INC
Unde r Contract to :
HARZA-EBASCO SUSI TNA JOINT VENTURE
Prepa red for :
ALASKA POWER AUTHOR ITY
Draft Report
JUNE 1984
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LIST OF TABLES
Table Number Title
3 .1 Lower Sus itna R iver Mainstem Data
for F reeze- up 1983
5 .1 Tal keetna -Summary o f Air Temperatures
and Freezing Degree Days,Sept .-Dec .1983
5 .2 S herman -Summary of A ir Tempe ratures
and Freez ing Degree Days ,Sept.-Dec .1983
5 .3 Dev i l Canyon -Summary of Air Temperatures
and Freezing Degree Days,Sept .-Dec .1983
5 .4 Watana -Summary of A ir Temperatures
and Freez ing Degree Days ,Sept .-Dec .1983
5 .5 Denal i -Summary of A ir Temperatures
and Freez ing Degree Days,Sept .-Dec .1983
6 .1 Relat ive Stage Levels at Se lected Tributaries
o n the Lower Sus itna R iver during Freeze-up
6 .2 S us itna R iver Ice Cover Lead i ng Edge Locat ion
During F reeze- up 1983
6 .3 Susitna R iver Ice Th icknesses in
January 1984
7 .1 Sus itna River Water Surface Elevat ions between
the Chulitna River Confluence and Gold Creek
Page
13
40
42
44
46
48
70
1983
71
72
106
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7 .2
7 .3
7 .4
7 .5
7 .6
7 .7
Chul itna River Confluence Stage Data
Gold Creek Wire Weight Read ings
Sus it na R iver Ice Poros ity Measu rements
Sus itna R iver a t Gold Creek Ice Discharge
Computations
Sus itna River Water Temperatures
Susitna River at Gold Creek,Water Temperatures
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109
113
114
118
119
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Number
1.1
3.1
3 .2
4.1
4.2
4 .3
4.4
4.5
4 .6
4.7
4.8
4 .9
4 .10
4 .11
LIST OF FIGURES
Title
Map of Susitna River Study Area
September 17 ,1983 ,Susitna River at RM 94
October 4 ,1983 ,Susitna River secondary
channels begining to dewater
Chulitna /Talkeetna/Sus itna confluence area,
October 1981
Chul itna /Talkeetna/Sus itna confl u ence area ,
October 1983
Birch Creek and Slough ,October 1983
Sunsh ine C reek and sidechannel,
.October 1983
Montana Creek and Sus itna co nfluence,
November 1983
Goose Creek confluence ,October 1983
Kashw it rna River confluence ,October 1983
Little Willow Creek co nfluence ,October 1983
Willow Creek confluence,October 1983
Deshka R iver confluence and entrance
to Kroto Slough ,October 1983
Yentna River confluence ,October 1983
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15
15
25
26
27
28
29
30
31
32
33
34
35
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Number
5 .1
5.2
5 .3
5 .4
5 .5
6 .1
6 .2
6 .3
6 .4
6.5
6 .6
LIST OF FIGURES
Title
Susitna River Basin,accumulating
freezing degree-days,September-
December 1983
Susitna River Basin ,Mean Monthly
A ir Temperatures,1983 and Historical
Slush ice at Denali Highway bridge
Frazil i n upper r iver canyon
S l ush ice forming border ice
Middle ,ojver on October 18, 1983
Border ice on Middle River,October 17,1983
Slush ice filling secondary channels on
the lower river ,October 2 1.1983
Susitna River at River Mile 9,
October 25,1983
Lower r iver on October 25 ,1983
Look ing upstream at r iver mile 9 ice bridge
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51
54
54
55
76
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77
78
79
79
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Number
6.7
6.8
6.9
6.10
6.11
6 .12
6 .13
6 .14
6 .15
6 .16
6 .17
6 .18
6.19
6 .20
6.21
6 .22
LIST OF FIGURES
Title
Accumulating slush in t idal backwater
reach of the lower river
Juxtapositioning of ice floes
Ice cover progress ion
Leading edge at RM 31 on November 1,1983
Leading edge progress ion r ates relati.e to
the Susitna thalweg profile
Entrance to Alexander Slough at RM 19 in
October,1983
Alexander Slough flooded on November 1 ,1983
Flooded snow and side channels,November 1,
1983
Mouth of Willow Creek on November 1, 1983
Mouth cif Kashwitna River on October 4,1983
Mouth of Kashw itna River on November 1, 1983
Mouth of Sheep Creek on October 4,1983
Mouth of Sheep Creek on November 1, 1983
Mouth of Goose Creek on October 21, 1983
Mouth of Goose Creek on November 1 ,1983
Groundwater sens itivity to ma instem stage
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81
82
82
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84
85
85
86
87
87
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89
89
90
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Number
6 .23
6 .24
6.25
6 .26
6 .27
6 .28
6 .29...
6 .30
6 .31
6.32
6 .33
6.34
LIST OF FIGURES
Title
Mouth of Montana Creek on October 4,1983
Mouth of Montana Creek on December 28, 1983
Parks Highway bridge at Sunshine on
November 24, 1983
Entrance to Sunshine Side Channel on
October 21, 1983
Head of Birch Slough on September 17, 1983
Head entrance to Birch Slough on November 26,
1983
Mouth of Birch Creek on September 17, 1983
Mouth of Birch Creek on November 21 ,1983
Mouth of Rab ideux Creek on October 21, 1983
Mouth of Rab ideux Creek on November 23, 1983
Near the Talkeetna River confluence ,
November 27, 1983
Relative stage levels at selected s ites during
1983 Susitna River freeze-up
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94
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95
96
97
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LIST OF FIGURES
I Number Title .Page
I 6.35 Ice cover sagging with decreas ing flow on 98
December 28 .1983
I 6.36 Lower River freeze-up sequence 99
6.37 Open lead near sunsh ine at RM 50 on 100
I December 28 .1983
6.38 Secondary leadi ng edge i n open lead on 100
I December 28, 1983
7.1 Ice crystals obtained from a slush ice raft 120
near Gold Creek on October 17. 1983
I 7.2 Ancho r ice dam at Rm 142.5 on 120
December 28 ,1983
I 7 .3 River Mile 130 near Sherman looking 121
upstream on December 28 ,1983
I 7.4 F ractured borde r ic e,ice bridge and new 121
leadi ng edge near Gold Creek on
I
December 28. 1983
7 .5 Middle River freeze-up sequence 122
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ACKNOWLEDGMENTS
I am indebted to Mrs .Nancy Larson for mak ing a conscientious effort in
obta ining reliable data at Gold Creek.Alaska Department of Fish &Game.
in particular Len V ining.who occas ionally allowed R&M Consultants the
use of their scheduled helicopter time.Granville Couey who would often
change schedules in order to accommodate this study and the pilots of Air
Logistics Inc o Assistance in editing the draft of this report was provided
by Joe LaBelle of the Arctic Environmental Information and Data Center .
am especially grateful to Steve Bredthauer of R&M Consultants for h is
support and involvement with this study.and to the word processing staff
at R&M Consultants.
Carl Schoch
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1 .0 INTRODUCTION
The Sus itna River ice s t udies continued in 1983 focusing on processes and
en v ironmenta l impacts during freeze-up and breakup on the r iver
downstream of the Chul itna confluence at r ive r mile (RM) 98 .5.From 1980
to 1982 the ice studies emphas ized the middle r iver (Talkeet na to Devil
Canyon )s ince ice in this reach w ill probably be most effected by seasonal
var iations in hydroelectric project operations .The tributaries entering the
Susitna below RM 98 .5 and the change in channel configurat ion should
dampen out project influence, on ice in the lower river ,to a great extent.
Attempts to mathemat ically model ice cover development on the midd le r iver
reach have assumed the arrival of an ice front at RM 98 .5 on a spec ific
date so that computat ions could begin to init iate an upstream progression
of ice .In order to more accurately define a freeze-up schedule for the
lower rive r ,the p rocesses influencing th is reach must be known.I n
addition,further justification for a lower r iver analysis stemmed from the
v iewpoint of enviro nmental impacts .The many side channels between
Talkeetna and Cook Inlet may support unident if ied fishery habitats that
could potent ially be impacted by winter flow modificat ion during proposed
project operation .This report presents the findings of the 1983-1984 ice
study beg inn ing with a br ief descript ion of the lower r iver morphology and
the sign if icant tributaries entering the system ,and cont inuing w ith a
discuss ion on meteorology and river ice processes.It has been assumed
that readers are famil iar with the prev iously published ice r eports
(R&M 1980,1981 ,1982)and therefore many of the fundamental concepts
have been only br iefly descr ibed o r are omitted ent irely .It is suggested
that the 1982 -1983 Sus itna R iver Ice Study (R&M, 1984)be rev iewed pr ior
to this report .Figure 1 .1 i llus trates a portion of the Susitna River bas in
under study.
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INLET
17
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MAP COURTESY OF
THE ARCTIC ENVIRONMENTAL INFORMATION AND DATA CENTER
SCALE:1 INCH EOUALS 18 MILES
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2.0 SUMMARY OF 1983-1984 LOWER RIVER ICE PROCESSES
·In 1983 fraz il ice on the Sus itna River was f irst observed near Gold Creek
on September 26 ,follow ing a four day period of mean Ja ily a ir
temperatures near -lOoC at the Denali weathe r station .Flow ing s lush
vo lumes fluctuated considerably during the f irst two weeks i n October
reflecting variat ions i n a ir temperatures.Most of th is s lush ice melted ,
absorb ing heat from the r iver water wh ich gradually cooled to near DoC by
mid-October .After October 15 a relatively constant f low of slush ice wa!.
observed pass ing Gold Creek .Most of this cont inued downst ream
eventually entering the river reach influenced by Cook I nlet tidal cycles.
High tides create a backwater effect extending many miles up the Sus itna
River.This had significant consequences on several hydraul ic parameters .
on the lower 13 miles of river in October.Water levels rose ,cross
sectional area increased and water velocity decreased causing the slush rca
to accumulate .Ice concentration qu ickly covered 100%of the surface are3
and when suff icient ly cold a ir temperatures and slow water velocity wa :;
encountered ,the unconso lidated slush ice froze in place forming an ice
bridge .The constant d ischarge of slus h ice continued accumulating at th e
upstream edge of the ice bridge and an ice cover began to progress
upstream .Where the channel grad ient and water ve locities were low,
advancement occurred rap idly with ice f loes abutting one another and
remaining on the water surface.When the ice front encountered hi gher
water velocities t hen crush ing and consol idations caused the ice cover to
th icken .The th icker ice cover d isplaced more water ,exte nd ing the
backwater area upstream unt il the h igh velocity section was drowned and
progression continued .
The rate of ice cover progression is primarily dependent on a ir
temperature.Air temperature controls the volume of frazil generated as
well as the ice cover stability .The lower 98 miles required over 40 days
to freeze-up i n 1983,c ompared to approximately 14 days in 1982 .Th is is
attributed to the number of freez ing degree-days accumulated during
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freeze-up .The total number of freezing degre,,-days at Talkeetna In
October 1983 ,amounted to 56 compared to the 1982 total of 172.
A slow progress ion rate generally results in lower levels of staging and
th inner ice at any given cross section.The discharge and in itial water
level are less when the ice cover forms later in the year relative to a year
when the progression rate is high.In 1982 a high progression rate froze
over the lower r iver by the end of October,when r iver d ischarges were
much h igher than those of November 1983.
The Yentna River contributed substantial volumes of slush ice,sign ifi-
cantly affecting the rate of freeze-up below its confluence w ith the
usitna. The rema ining tributaries,however ,had less influence ,with the
Chulitna and Talkeetna Rivers generating the most frazil-an est imated
15-20%combined total of the volume below the confluences w ith the
Sus itna.
Many of the dewatered s ide channels adjacent to the Susitna mainstem on
the lower r iver were flooded during freeze-up in 1983,some temporar i ly
while the ice front advanced past the upstream entrances and others for
the duration of the winter .Slush ice was observed to enter only a few
s ide channels but in insufficient quantit ies to develop an ice cover .A
myriad of side channels and sloughs precluded detailed impact analyses
during freeze-up and further studies should awa it identification of known
aquatic habitats.
Deterioration of the ice cover on some reaches of the lower r iver began
immediately after the i nit ial progress ion .Extens ive leads eroded through
the cover ,exposing open water between thick layers of ice stranded on
the banks.Cold air temperatures from December through March appeared
to dom inate all other factors controll ing ice stab il ity and the destruct ion
processes were stalled.The leads began to close aga in by lateral growth of
border ice and accumulat ion of fraz il at the downstream end .Increas ing
da ily duration of exposure to solar rad iat ion beg ins to have a marked
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effect in April.Exist ing iedu:,lengthened as the floating ice cover melted
from underneath by.heat ga ined from fr iction (from the flow ing water)and
once the snow had melted ,solar radiation bearing d i rectly on the ice
surface caused the fam il iar candling process.This gradual melting seemed
to characterize "breakup "on the lower river .Fragmenting of the ice,
wh ich is a more typical process on the middle river ,occurred only when
stages increased sufficiently to exert a crit ical lifting force .The broad
flood plain relative to the area occupied by channels on the lower r iver
prevented a rap id i ncrease in stage with rising discharges .When ice jams
did occur,such as when ice debris from the middle r iver accumulated
against a so lid cover on the lower r iver,then water spilled over onto the
flood plain and bypassed the congested ma in channel.Although eros ion
and damage to vegetation has been observed during breakup ,these were
isolated inc idents and considered insignificant compared to damage incurred
during summer floods .
Further stud ies o n the lower r iver w ill cons ider development of the ice
br idge near Cook I nlet ,ice volume determ inat ions for the Yentna River,
and impacts to fisheries hab itats during freeze-up .Issues concerning
with-project effects on the ice regime include location and timing of ice
bridge format ion ,volume of ice requ ired to freeze-up t he lower r iver ,and
expected max imum stage levels .
During w inter project operations,ice generat ion on the Sus itna River w ill
be delayed,s ince reservoir releases w ill have temperatures h igher than
natural flows for winter .This relatively warm water will have to cool to
DoC before fraz il ice can be generated.The length of r iver requi red to
cool the water is dependent upon a ir temperature ,and the DoC cond ition
may not occur below the project until November .Present observed
cond itions appear t o req u ire h igh ice concentrat ions to form the ice bridge
i n October .The Yentna River may not contribute suffic ient volumes of
s lush ice to ach ieve the crit ical concentration requ ired for bridging .
This volume should therefore be quant if ied so that a with-project freeze-up
schedule can be defined .
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The volume of ice required to f ill the lower r iver is important so that a
freeze-up schedu le for the middle r iver can be determ ined.Midd le r iver
ice cover progression -probably w ill not begin until the lower river is
f!"9zen over .When fraz il generation begins,a specific vo lume w ill be
requ ired to cover the lower r iver.This volume can be computed based on
ice th ickness and surface area information .
A th ird cons ideration is potential impac ts to side channels under
w ith-project cond itions.Winter flows w ill be higher than present flows,so
staging and ice th icknesses will increase accordingly.Quantify ing natural
cond it ions will assist in analyzing impacts to f isheries habitats.These are
some of the issues emphasized in the proposed 1984-1985 ice study and will
be required to adequately assess project influences on the lower river ice
regime.
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I 3 .0 LOWER RIVER MORPHOLOGY
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The Sus itna River downstream of the Chulitna confluence runs for about 98
miles to Cook Inlet .This reach will be referred to here as the lower river
to different iate it from the upper river which runs from the headwaters in
the Alaska Range to Dev il Canyon ,and the middle r iver which continues
from Dev il Canyon to the Chu litna confluence.
The lower r iver has been further subd iv ided i nto f ive reaches ,each w ith
d istinct c haracterist ics (see Append ix C for r iver mile delineation ).
Segment runs from RM 98.5 at the Chul itna confluence to RM 78 near the
confluence of Montana Creek .Segment 2 continues from RM 78 to RM 51 ,
which is approximately the upstream end of the Delta Islands .Segment 3
runs through the Delta Islands to RM 42 .5,with Segment 4 continuing to
the Yentna River confluence at RM 27 .Segment 5 contains essentially the
rema inder of the reach to Cook I nlet .The exact r iver mouth is difficult
to def ine because the e xtreme t idal range in Cook I nlet creates a back-
water estuary .For th is report RM 9 marks t he downstream edge of
Segment 5 .These 5 r iver segments represent an attempt to separate the
lower r iver reach i nto areas wh ich show obvious morphologic s imi larit ies
based on aerial reconna issance and analys is of aerial photography.With
further study ,these s imilarities may prove to be associated with aquat ic
habitat types and hydraulic characteristics.This may lead to defining open
water flow condit ions and ice processes unique to each segment.
The follow ing d iscuss ion presents brief descriptions of each r iver segment
includi ng pert inent d ata (Table 3 .1)based on photo i nterpretation and
f ield obse rvations .
Segment 1 -River Mile 98.5 to River Mile 78
The river through th is reach has multip le braided channels with more
channels appearing at higher flows (F igure 3 .1).The main channel or
thalweg meanders through a wide floodplain often more than 5 ,000 feet
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wide.The floodplain consists mostly of gravel bars and some partially
vegetated island s.Several complex s ide channel systems ex ist but these
are generally flooded only at flows exceeding 13 ,000 cfs at Sunsh ine and
are side sloughs at .Iower discharges.These side channels are separated
from the mainstem by large heavily vegetated islands,and may occur along
either the left or right bank.Birch ,Sunshine ,Rabideux and Whitefish
Sloughs are the most extensive and significant side channel systems along
this reach.
Six major tributaries enter this reach including the Chulitna and Talkeetna
Rivers .Lesser contributions are added by Trapper ,Birch,Sunsh ine and
Rabideux Creeks .
The average gradient is 'about 5 ftlmi.Surface velocities have been
measured in.excess of 5 ftlsec prior to freeze-up at flows less than 10,000
cfs (USGS at Sunshine).The grad ient is less steep at the upper end of
the reach with the slope and water velocities increasing near the Parks
Highway bridge .The river width is highly variable with a maximum width
at RM 92 .0 of 7,000 feet and a minimum of 1,000 feet at the Parks Highway
bridge ,which is also the only place on this segment where the f low is
confined to one channel for the entire flow range.
Segment 2 -River Mile 78 to River Mile 51
Th is reach is characterized by extens ive s ide channel complexes a long the
ent ire reach .These cons ist of a network of i nterconnecting channels
wh ich are normally flooded only at h igh flows or during the elevated
stages induced by an ice cover .Many of the outermost channels in the
complexes are fed by one or more tributaries wh ich keep w"ter flow ing ;n
a small portion of the s ide channel regardless of the ma instem flow.S ix
s ignif icant tributaries enter this reach ,although only Montana Creek
enters the Susitna mainstem directly .Goose Creek ,Sheep Creek ..
Kashwitna River,197 Mile Creek and Caswell Creek enter s ide channels
which are isolated from the mainstem except at high water stages .
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The grad ient through th is reach starts out at 6 ft/m i and decreases n ear
the Delta Islands for an ave rage of 5 .6 f t/m i.This segment has t he
steepest s lope on the lower ri ver and subsequently the h ighest velocit ies .
Due to mechan ical th icken ing,th is reach also has vhe th ickest ice cover .
The mainstem (excluding the side channel complexes)appears similar to the
main channel in Segment 1 with a broad expanse of gravel and sand bars
exposed at low flows when the ma instem is generally confined to a s ingle
channel (F igure 3 .2).The maximum width of the flood pla in is 6 ,000 feet
and the minimum is 1 ,000 feet .The majority of the gravel bars are devo id
of vegetat ion.High summer flows generally inundate the gravel bars ,w ith
debris carried along by the flow often pil ing up on the islands as log
jams . At high flows,the water breaches the entrances to s ide channels
and spills i nto these systems.The s ide channels seem to funct ion
primarily as overflow channels,di verting water away from the ma instem
during floods .
Segment 3 - River Mile 51 to R iver Mile 42.5 (Delta Islands)
This reach runs through an i nt ricate system of islands .The ma instem at
some high flows becomes diffused and is d ifficult to differentiate from side
channels .Only at the low flows pr ior to freeze -up can the thalweg be
defined .Even then it is spl it i nto two channels flowing along the extreme
left and r ight ban ls ,respect ively .The majority of the side channels are
dewatered at these low flows.The maximum channel w idth is 4 ,500 feet at
RM 51 ,w ith the narrowest port ion of 700 feet at RM 42 .5.RM 42 .5 also
marks the joining or convergence of the two ma in channels emerg ing from
the Delta Is lands and the end of th is segment .Field i nvestigations
documented ground water seeps entering several of the s ide channels,
providing these w ith a separate source of water isolated from the
ma instem .The groundwater seeps are probably related to the ma instem
stage since the contribution of flow by groundwater iii the s ide channel
seems to d imin ish with lower water levels i n the ma instem .
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The gradient through this reach starts out at 6 ft/m i and decreases near
the Delta Islands for an average of 5.6 ft/mi.This segment has the
steepest s lope on the lower river and subsequently the highest velocit ies .
Due to mechan ical thicken ing ,this reach a lso has t he th ickest ice cover.
The mainstem (exclud ing the s ide channel complexes)appears sim ilar to the
main channel in Segment 1 with a broad expanse of gravel and sand bars
exposed at low flows when the mainstem is generally confined to a s ingle
channel (Figure 3 .2).The max imum width of the flood p lain is 6,000 feet
and the min imum is 1,000 feet .The majority of the gravel bars are devoid
of vegetation .High summer flows generally inundate the gravel bars ,with
debris carried along by the flow often pi l ing up on the islands as log
jams . At h igh f lows,the water breaches the entrances to side channels
and sp ills into these systems .The side channels seem to function
primarily as overflow channels,d iverting water away from the mainstem
during floods .
Segment 3 -River Mile 51 to River Mile 42.5 (Delta Islands)
Th is reach runs th rough an intricate system of island s.The mainstem at
some h igh flows becomes diffused and is d ifficult to d ifferentiate from side
channels .Only at the low flows prior to freeze-up can the thalweg be
defined .Even then it is split i nto two channels f low ing along the extreme
left and right banks ,respectively .The majority of the s ide channels are
dewatered at these low flows.The maximum channel w idth is 4,500 feet at
RM 51,with the narrowest portion of 700 feet at RM 42.5.RM 42.5 also
marks the joining or convergence of the two main channels emerg ing from
the Delta Islands and the end of t his segme nt.Field i nvestigations
documented ground water seeps entering several of the side channels,
prov iding these w ith a separate source of water isolated from the
mainstem .The groundwater seeps are probably related to the mainstem
stage s ince the contribut ion of flow by 3roundwater in the s ide channel
seems to dimin ish with lower water levels in the mainstem.
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Two tributaries enter this reach along the east bank .Little Willow Creek
and Willow Creek initially flow into a s ide channel wh ich then enters the
east mainstem at RM 52 about 1,000 feet downstream of the Willow Creek
confluence ..:
The river gradient reduces substantially frc.n 5.6 ft/mi in Segment 2 to
2 .9 ft/mi i n Segment 3 .This may provide an explanation for the comp lex
morphology of this reach.The lower gradient results in reduced water
velocities wh ich could result in less degradation and perhaps some
aggradation causing the channels to meander and intertwine .
Segment 4 -River Mile 42.5 -River Mile 27
This reach is similar to Segment 2 with a well defined mainstem and numer-
ous side channels along both the left and right banks .The Deshka River,
at RM 40.6,is the only major tributary entering this segment .
Kroto Slough represents one of the major s ide channel complexes in th is
segment.The upstream entrance is located about one-half mile below the
confluence of the Deshka River .Although this side channel has several
branches which connect w ith the Sus itna ma instem ,one channel cont inues
on s eparate lv to the Yentna River.This side channel system dewaters at
f lows less than 13 ,000 cfs (USGS at Sunshine),however,when the .
ma instem is ice covered the stage i ncreases enough to flood the channel,
so for the major portion of the year th is s ide channel flows w ith Sus itna
and Desh ka River waters .
An interesting feature is that the Deshka River water does not mix
immediately with the Sus itna flow .At low Sus itna flows,a relat ively clear
water plume ex ists along the r ight bank for several hundred yards below
the confluence and th is low turbidity water wh ich enters Kroto Slough .
This s ide channel receives water with a lower sediment load than would be
expected if the Deshka water was more thoroughly mixed with the Su srtna ,
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Th e grad ient th rouq h :thi s r e ac h cont in ues to decrease with respect to
p reced ing segments .Th e g rad ie nt ave rage of 2 .6 ftJ mi is a lso ref lected in
t he lower surface water v el ociti es . Ve loc ities from 3 to 4 f t/sec have been
measured when Sunsh ine fl ow is 10,000 cfs .':hannel widt hs range from a
max imum of 5,500 feet at RM 32 .2 to the na rrow section of 800 f eet at RM
38.5.T he s ide channels th rough this reach are strictly overflow channe ls
at h igh water a nd at f lows be low 13,000 cfs (USGS at Sunsh ine)are
gene rally dewatered .
The vegetated islands are i nterlaced by channels which appear to be
substantially eroded at flow capacity .Th is is ev ident by the stands of
mature cottonwood trees extending to the edges of steep cutbanks,as well
as the volume of debris in these areas.
Numerous relic channels to the west of the mainstem along Segment 4
suggest a f low h istory quite d ifferent from the present regime .These old
channels are now most ly v egetated but are eas ily d iscern ible from the a ir
and on photographs .The meandering nature of these channels suggests
that ,h istorica lly,the r iver g radient was probably less than today.These
channels are now swamplands w ith few stands of large trees and entire ly
bypassed b y the present ,s t ra ighter cou rse of the r iver .
The lack of .Iarge trees a long the west overbank cont rasts sharp ly with the
vegetation surrounding the prese nt flow system .The entire east bank is
forested w ith large ,mature cottonwood trees as are the islands i n the s ide
c ha nnel complexes and ma i nstem.Th is may be ev idence of a sh ift ing flow
pattern t owards the east ,espec ially cons idering the eros iona l features of
these islands and the ent ire east bank,wh ich is characterized by steep
cutban ks and matu re vegetation to the edge of the water.Along the west
bank the scrub ,b irch and cottonwood trees grow only on h igher ,drained
ground .Below the Yentna River confluence the mature trees ex ist along
both banks.
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Segment 5 •Rive,.Mile 27 to Rive,.Mile 9
This reach begins at the Yentna Confluence and extends to RM 9 near
Cook Inlet and represents an area of transition from a rive,.system to an
estuary .The extreme tidal range in Cook Inlet is over 25 feet.creating a
long backwater zone.The exact longitudinal range has yet to be
determined but has been observed up to RM 12 .The Yentna River
contributes approximately 40 percent of the annual flow measured at
Susitna Station (RM 25.9)by the USGS .However.this is not cons istent
at all flow ranges .The proportion may vary greatly depending on storm
system movement and the glacier mass wasting characteristics of each
system.The Yentna discharge approximates the flow on the Susitna
measured at Sunshine during low flow periods but often does not respond
simultaneously to the same hydrograph peaks.
A dominating feature of th is segment is Alexander Slough or the Sus itna
west channel.This represents a major side channel at most open water
flows but dewaters j ust prior to freeze-up.When mainstem water enters
this side channel the flow essentially becomes isolated and does not
re-enter the mainstem except at flood stages.Then an interconnecting
channel at RM 9 .7 floods .At low flows,such as prior to freeze-up ,the
s ide channels are generally dewatered and the mainstem is confined to one
channel.although.encompassing many exposed sand bus .
The slope through this reach was determined from USGS topograph ic
contours and is about 1.5 ft/m i,w ith average surface veloc ities of 2 to 3
ft /sec .
Other tributaries enter ing this reach include Alexander Creek and Fish
Creek .Alexander Creek enters Alexander Slough and continues out to
Cook Inlet without join ing the mainstem .Fish Creek drains the
swamplands adjacent to,and-east of,the Susitna east channel an d enters
the mainstem at RM 1. As can be expected ,the grad ient is so low here
that flow from this tributary is g reatly restricted by backwater created by
ma instem stages .
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TABLE 3.1
LOWER SUSITNA R IVER MAINSTEM DATA
fo r FREEZE-UP 1983
Segment 1 2 3
River Mile 98 .5 to 78 78 to 51 51 to 42 .5
Avg .G rad ient (ft/mi)5.0 5 .6 2 .9
Widths(1)(2):Max .(RM)7000 (92 .0)6000 (73)4500 (51)
Min .(RM) 1000 (83 .8)1000 (75 .8)700 (43 .5)
Entering Tributaries Chulitna R .Montana Cr .Little Willow Cr.
Talkeetna R .Goose Cr.Willow Cr .
Trapper Cr .Sheep C r .
Birch Cr.Caswell Cr .
Sunshine Cr.Kashwitna R .
Rabideux Cr .197 Mile Cr .
Avg .Freeze-up Staging (ft .)4 .6 5 .1 2 .8
Avg .Ice Thicknesses (ft.)6.3 6.8 4 .0
Avg.Surface Veloc ity (ft/s)5 5 4
Approx .Freeze-up Date 12/8 11116 11 /6
Approx .Ice Vol ume (cu.f t.)7 .0xl08 1 xl09 2x l08
Locat ions 0 )'Major 98 .5 - 97 74 - 72 .5 0
Open Leads After 95 .5 - 93 71 .5 - 70 .5
Prog ress ion 86 - 85
(Mainstem Only)84 - 78 67 -61.5
Ice Bridges (l ocation)0 0 0
S hore Ice Width (ft.)3 - 6 0-2 0
(1)Widths do not i nclude major s ide channel complexes or s loughs.
(2)Locat ions are referenced to the river mile (RM)number .
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TABLE 3.1 -(cent')
LOWER SUSITNA R IVER MA INSTEM DATA SHEET
f or FREEZE-UP 1983
Segment 4 5
River Mile 42 .5 to 28.5 28.5 to 9
Avg.Grad ient (ftl mi)2 .6 1.5
Widths (1 )(2):Max .(RM)5500 (32 .2)7000 (0)
Min .(RM)800 (38 .5)800 (15 .8)
Entering Tributaries Deshka R .Yentna R .
Alexander C r .
F ish Cr .
Avg.Freeze-up Staging (ft .)3.5 2 .5
Avg.Ice Th icknesses (ft .)5.5 4 .0
Avg .Surface Veloc ity (ftls)3 -4 2-3
Approx .Freeze-up Date 11/4 10/31
Appro"Ice Vo lume (cu.f t .)4x108 2x108
Loca t ions of Major 0 8 -0
Open Leads After
P rogress ion
(Main stem O n ly)
Ice Bridges (l ocat ion)0 (RM 9 )
Shore Ice Width (f t.)0 0
(1)Wi dt hs do no t i n clude major s ide c hannel c omplex es or sloug hs .
(2 )Locat ions are referenced to t he r iver mile (RM)number .
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FIGURE 3.1
September 17 ,1983.Susitna R iver looking upstream from RM 94.--al keetna
River confluence is at middle r ight .Note the broad floodp lain re lat ive to the
r iver channels.
FIGURE 3 .2
Oc tober 4 ,1983 .Su sitna R iver look ing upstream f rom
c han nels a re d ew ater in g and a ma jor portion o f the f low
chan nel .
RM 78.S econdar-y
i s r est r ict ed 1'0 one
SUS/TNt.J OIN T VENTU~'E
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O l-~~~=~!j':V~/l,============
R&M C::::JNSUl-TANTS.INC......D..... . . .I'Ic:o...OQ '~'.•..ANN.p e !l.U ."'C "'O .~
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Chulitna River
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4.0 LOWER RIVER TRIBUTARIES
Caswell Creek
Kashwitna River
197 Mile Creek
Little Willow Creek
Willow Creek
Deshka River (Kroto Creek)
Yentna River
Alexander Creek (west channel)
Fis h -Cr-eek (east channel)
Chulitna R iver
Talkeetna River
Trapper Creek
Birch Creek
Sunsh ine Creek
Rabideux Creek
Montana Creek
Goose Creek
Sheep Creek
Agg radation i nfluences the flow distribu tion at the confluence of the
Chul itna and Sus itna Rivers .The morphology of this a rea appea rs to
be constantl y chang ing (Figure 4 .1 and 4 .2).For the past 3 years
the Chul itna flow was evenly distr ibuted betwee n two ma jor channels
at the con fluence.During the 1983 r iver freeze -up it became
apparent that the channel conf igu rat ion had changed cons iderably .
The west channel dewatered dur ing the second week i n November
Despite the vast differences In drainage areas the water volume
contr ibuted b y the Chul itna closely approximates the total volume of
the Susitna measured at Gol9 Creek(USGS).The Chulitna
(Talkeetna Station)drains an area of ,2 ,570 square miles and the
Susitna (Gold Creek)drains an area of 6 ,160 square miles .
The morphology and what is presently known about the flow
character istics of each tr ibutary w ill be described:
The f ollowing are t he most sign if icant tributaries to the lower r iver
w ith respect to water volume and sed iment load contributions :
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when the Chulitna discharge was between 3500-3000 cfs (USGS at
Chul itna)and the Susitna approximately 3000 cfs (USGS at Gold
Creek).The east channel contained more water than i n prev ious
years .The h igher flows in the east channel may have prevented the
format ion of the ice bridge at RM 98 .5 i n 1983.Other s ign ificant
morphological changes that may be attributed to sed iment aggradation
include a shift in Susitna flow from the east bank to the west at the
three rivers confluence .In previous years the Sus itna flowed close
to the east bank and merged w ith the Talkeetna River at RM 97 .In
1983 th is east channel dewatered at approx imately 5 ,000 cfs (USGS at
Gold Creek),due In part co aggradat ion ,but a lso poss ibly due to
degradation of the west channel,wh ich now carries a major po rt ion of
the Susitna and Chulitna flow .
U .S.Geolog ical Survey discharge data on the Chulitna River are
reported i n the Water Resou rces Data annual report.
Talkeetna River
This r iver jo ins the Susitna at the town of Talkeetna (F igure 4 .2).
At Sus itna flows i n excess of 5 ,000 cfs (USGS at Gold Greek ),the
Ta l keetna flow joins a portion of the Sus itna at RM 97 .At these
flows the Su s it rr a stage is h igh enough to flood several channels along
t he east bank between the Chu litna R iver confluence at RM 98.5 and
RM 97 .At Sus itna flows less than 5 ,000 cfs these east channels are
dry and the mainstem of the Sus itna runs to the oppos ite west ban k .
The Talkeetna confluence under these conditions sh ifts downstream 2
miles to RM 95.Th is is s ignif icant during the f reez e-up process . I n
years ,when the Sus itna east channel thresho ld e levat ion was lowe r,
the s lush ice f rom the Sus itna wou ld accumu late between RM 9 7 a nd
RM 98 and form an ice bridge .Th is ice b r idge would not , how ev er ,
i nitiate an upstream ice progress ion .
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When the Susitna joins the Talkeetna R iver at RM 97 at high flows,
the result ing backwater inundates the alluvial fan at the mouth of the
Talkeetna.The higher stage and i ncreased cross-sectional area
reduces the Tal keetna water velocity and dissipates the flow energy
over a broad area.During freeze-up,when Susitna flows decrease to
less than 5,000 cfs (USGS at Gold Creek)and the east channels have
dewatered,the Talkeetna flows unrestricted over the alluvium,
maintaining the velocity that is natural to the prevailing channel
grad ient .Under these conditions the flow energy is concentrated and
the unconsolidated gravels rapidly degrade,leaving an entrenched
channel.The same situation occurs at the Chulitna confluence but is
less obvious because of the extremely broad flood plain.Post-project
winter flows will surely be in excess of 5000 cfs and the confluences
of these two rivers may continue to aggrade throughout the year .
The U .S .Geological Su rvey ma inta ins a gaging station on the
Talkeetna and reports the data in the Water Resources Data annual
report .The National Weather Service - R iver Forecast Center also
mon itors the water level at the Alaska Railroad bridge during the
open water season .
Trapper Creek
No d ischarge records have been located for th is stream ,however the
flow cont r ibution is estimated to be small .It jo ins the Sus itna from
the nort hwest near RM 90 .The actual confluence may v ary
depend ing on mainstem Sus itna water levels .At low flows the con -
fluence i s at RM 90,wh ile at high flows the confluence may sh ift to
RM 91.
Birch Creek
Birch Creek joins B irch Slough about 4000 feet above the Susitna
confluence (F igure 4.3).Birch Slough is a side channel of the
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Susitna at high ma instem flows .It runs from the head entrance at
RM 93 .2 on a meandering course along the Sus itna east bank .When
the slough entrance is dewatered (at approximately 14 ,000 cfs ,
Sunshine gage),groundwater slJeps pr-ovide enough water so that
beaver ponds in the slough remain flooded .The combined flow from
the slough and creek enter the Susitna ma instem near RM 88.
Discharge measurements have been conducted on this stream,wh ich
joins a slough before entering the Susitna mainstem at RM 88 .The
Alaska Department of Fish and Game (ADF&G)monitored flows during
the 1982 open water season and obta ined four discharge
measurements.R&M Consultants determined flow rates i n September
and October of 1983 at four specific mainstem d ischarges and
documented the backwater effect at the mainstem confluence .Flows
generally range from 36 to 120 cfs .The Susitna creates a signif icant
backwater area at high flows but th is has not been observed to affect
the reach upstream of the slough /creek confluence.
Sunshine Creek
Th is tributar-y joins a large s ide channel complex about 1 .5 mi les
upstream of the Susitna conf luence at RM 84 (Figure 4 .4).The s ide
channel dewaters at low flows prior to mainstem freeze-up .At this
time the creek provides the only flow th rough the lower port ion of
the channel.ADF&G obtained four discharge measurements i n 1982
0 .7 miles above the mouth .Flows ranged from 32 to 104 cfs .At
high ma in stem flows the s ide channel is flooded and creates an ex-
tens ive backwater,affecting at least the first 0 .7 miles of the creek .
Rabideux Creek
Th is cr-eek enters the ma instem directly at RM 83.1 .Early attempts
to measure the flow resulted i n first defining the extensive backwater
zone influencing the mouth .In order to develop a rat ing curve ,the
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ADF&G h ad to conduct meas urements 1.7 mi les u ps tream from th e
conf l uence .F low measurements r anged f rom 129 to 223 cfs during t he
summer of 1982 ,wh ile w in ter flows are estimated to be less than
5 cfs .
Montana Creek
T h i s tr ibutary en ters the Sus itna d irect ly at RM 76 .9 .Mainstem
ve locit ies prevent s ign if icant sed ime nt depos its from accumulat i ng
beyond a we ll def ined ban k lin e .At low ma instem sta ges th is stream
y ields h ig i:velocity f low s,wh ich degrade a we ll developed a lluv ial fan
(Figure 4 .5 ).The fan area was not observed to f lood du r ing h igh
Sus itna flows.The only documented flooding of th is fan was during
ice cover proS/ression on the Sus itna main stem adjacent to the
confluence .
T he USGS ma i nta ined a crest stage recorder on Montana C ree k from
19 63-1 9 72,in 19 78 a nd in 198 1 .Misce llaneous measu reme nts were
made b y R&M Cons u ltants i n 1983 .The Na-t iona l Weather Serv ice has
ma inta ined a partial stage r ec ord s ince 1973.
Goose Creek
A complex system of d istr ibutar ies un iquely character izes the
con f luence of th is c reek (Fig ure 4 .6).Originati ng as a s ing le
cha nne l from t he east ,the flow encounters a grave l depos it near th e
conf luence .T his u nconsolidated depos it d istr ib utes the fl ow between
two channe ls .One c hanne l i s d i rected north and enters a s ide
cha nnel des ignated as Goose C ree k S loug h .The seco nd chan nel
co nt inues westward and sp l its aga in into three separate channels,one
of wh ich enters the Sus itna ma instem d irectly at RM 73 .The other
two d iverge to the south and flow for about three-quarters of a mile
before jo in ing a side channel .Several minor channels also e xit the
gravel depos it and flow south .The s ide channel i nto wh ich these
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distributa r ies flow is flooded only at mainstem discharges in excess of
approxi mately 13,000 cfs (USGS Sunshine).At lower flows Goose
Creek provides the majority of the water flowing through the side
channel.
The USGS maintained a crest stage recorder on this creek from
1963-1971.
Sheep Creek
This is a stream w ith no record of d ischarge measu rements.It enters
a s ide channel complex near RM 67 .This side channel joins the
mainstem near the confluence of the Kashwitna River at RM 62 .5 .At
low Susitna flows,the side channel dewaters so that Sheep Creek
provides the only flow ing water .The mouth of Sheep Creek is
effected only by flows from the side channel and the subsequent
backwater zone is controlled by the water level in the side channe l.
At high mainstem flows the head entrance of the side channel is
flooded and the resultant water level increase controls the extent of
the backwater up Sheep Creek.The mainstem,therefore ,i ndi r-ectlv
influences the backwater zone .Morpholog ical changes at the side
channel entrance,such as aggradation cr degradation of the th res hold
elevation,controls the exact Sus itna discha r .-effecting Sheep Creek ,
In 1983,the backwater zone was observed to ext'en d upstream to near
the confluence with Sheep Slough at Sunsh ine flows of about
60,000 cfs .
Kashwitna River
The Kashwitna confluence also varies with Susitna water le vels
(Figure 4.7),During the summer the Sus itna ma instem spills o ver
numerous,laterally or iented side channels and joins the tr ib utary at
about RM 61 .Prior to freeze-up these short side channels dewater
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w hich sh ift s the conf luence down to RM 60 .Discha rge r ecords h ave
not been fo und f or th is stream.Stag ing during the ice c ove r
progress ion creates a backwater area near RM 60 but i n 1983 d id not
s ign ifica nt l., i nfluence t he f low r egime.During the open wa ter season
a boat laun chin g f ad lity operates on the Kashw itna ad jacent to RM.6 1.
T his ramp area seems to be routi nely d redged t o ens u re adequate
wa ter dept h for motorized vesse ls .
197 Mile Creek
The des ignat ion stems from the Alaska Ra ilroad milepost at the bridge
cross ing th is stream .Th is slow-mov ing creek w ith li ttle discharge
ma inly drains surround ing swampland and muskegs .The water is
heav ily loaded with organ ic material and chemical by-products from
decompos ing vegetation .It enters a s ide channel complex near RM 60
wh ich joins Litt le Willow and Willow Creek before entering the Sus itna
ma instem at RM 50 in the Delta Islands "rea .The entrance to th is
s ide channe l dewaters at mainstem f lows less than 13 ,000 cfs (USGS at
Sunsh ine ),h oweve r,gro u ndwater seeps and the tr ibutaries p rov ide a
steady stream a long the eas tern-most channel with in the comp lex.
Th is cree k is no t co ns idered nav igab le but the s ide chan ne l ma y be
negot iable by some boats at ma in stem f lows over 30,000 cfs (U SGS at
Sunsh i ne).R&M Consultants measu red a d ischarge of 14 cfs on
Septembe r 7 , 1983.
Little Willow Creek
Th is clearwater s tream enters t he s ide channel ment ioned above f.il):,e
to the downstream end between one-ha lf and o ne mile above t he
confluence with the ma instem at RM 50 (Figure 4 .8).The stream is
na v igable for orily about one mile above the confluence with the side
channel,and only during h igh fiows.A low flow part ial record was
obta ined by the USGS in 1978.
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Willow Creek
A relatively fast moving stream capable of transporting enough sedi-
ment to produce an alluv ial depos it at the confluence w ith a Su s itna
s ide channel (Figure 4 .9).The flow from.th is creek j oins the east
channel ma instem at about RM SO .This stream has been gaged by
the U .S.Geological Survey since 1978 ,with add itional miscellaneous
measurements at various s ites .The mean monthly flow r ange during
water year 1982 ranged from 37 cfs to 1281 cfs .Jetboats and
airboats run regularly between the mainstem and the Parks Highway
Br idge boat ramp .
Deshka River
This river enters the S us itna ma instem directly at RM 40 .6 (F igure
4 .10).The water is relat ively deep ,clear and slow mov ing.No
apprec iable alluv ial deposits accumulate at the confluence .The
stream has continuous flow records from the U .S .Geological Survey
s ince 1978. In water year 1982 mean month ly flows r anged from 177
cfs to 2 ,561 cfs .T h is nav igab le r iver is a popu lar sport f ish ing area
du ri ng the open water season .
Yentna River
Th is major tr ibutary enters the Susitna system at RM 28 ,cont ribut ing
approx imately an equal volume of water to that measured on t he
S usitna at S unsh ine or about 40 percent of t he tota l v olu me meas u red
at Su sit na Station (F igure 4 .11).T he sed iment load appears to be
substa ntial.Being glacial i n or igin,the part icles are small en ough to
rema in e ntra ined and are not depos ited in substantial quant ities wh e re
the two r iver s ystems meet .S ince October 1980 ,th e US G S ha s
mon ito red th e d ischarge about 14 mi les above t he conflu ence .I n 198 2
flows ranged from a h igh daily discharge of 105,000 cfs to a min imum
da ily flow of 2 ,000 cfs.
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Alexander Creek
Th is slow clearwater stream enters the west channel of the Susitna
near the community of Alexander .The sediment load is probably low
throughout the year .The creek is navigable at h igh flows by jetboat
and at low flows by airboat .When the west channel entrance
dewaters at RM 19 the only flow i n this la rge channe l is from
Alexander Creek .The channel then cont inues to Cook Inlet without
joining the eastern ma in Sus itna channel .
Fish Creek
Th is is a very slow mov ing stream draining muskeg and swamplands
to the east of the river near the estuary .The stream mouth is
effected only by high Susitna mainstem·fl aws when the side channel at
RM 10 floods .An extensive backwater area has been documented to
extend several hundred feet up th is creek,which further attests to
its low veloc ity and d ischa rge .Summer res idents on Flathorn La ke
use th is tr ibutary to access the ma instem Sus itna and cont inuing to
Alexander Creek .Ma instem ice cover progress ion does not flood t he
s ide channel,and therefore has no influence on the creek .
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_TALK EE TNA RIV ER
SUSITNA J OINT VENTUR E
CO NFLUENCE OC TOBER 1 8 1 881
25
FI GURE 4 .1
R&M C ON SUL.TANTS,INC.....0.........D.O"OO '.T.~............."'.V."O.•
WEST CHANNEL
CHULITNA
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SU SITNA
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---~-----
SUS/TNA JO/NT VENTURE
THRO UGH THIS CHANNEL .
TALKEETNA RIVER
THIS BERM CONTROLS THE F LOW
SIX DAYS AFTER THIS PHOTO WAS
T AKEN T HE SIDECHANNEL DEWA TERED
~..~-
,.~:,.,...
.....\')0"
'\I ....·,-~'?
26
FIGURE 4.2
..C HULITNAISUSITNAITALKEETNA CONFLUENCE
R & M CONSULTANTS,INC.....0........o ao u::t Cl l eT.."...I\t .........,.v."o••
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l ~~
BIRCH CREEK CONFLUENCE OCT OBER
SUSITNA JOINT VENTURE
,".1,
27
FIGURE 4.3
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I ===========SUNSHINE CREEK CONFLUENCE OCTOBER 25 .1983 =======_
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FIGURE 4.4
28 SUS/rNA JOI NT VENTURE
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MONTANA CREEK CONFLUENCE OCTOBER 27.1983 I
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FIGURE 4.5
29 SUSITNA JOINT VENTURE
G OO SE CREEK CONF LUENCE OCTOBER 25.1983
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30 SUSITNA J OINT VENTURE
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KASHWITNA RIVER OCTOBER 25,1983
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3 1 SUSITNA J OI NT VENTURE
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WILLOW CREEK C ONFLUENCE OCTOBER 25 .1983
~••S US IT NA EAST
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3 2 SUSITNA J OI N T V ENTURE
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CREEK
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CONFLUENCE OCTO BER 25,1983 .~.'
I R&M CONSULTANTS,INC••Na.""....0_0...00 ,.,...I.A............"'.v ....O••
FIGURE 4.9
SUSITNA JOINT VENTURE
DESHKA RIVER CONFLUENCE OCTOBER 25,1983
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34 SUSITNA JO INT V ENTURE
YEN TNA RIVER CONFLUENCE OCTOBER 25,1983
SUSITNA J OINT VENTURE35
FIGURE ••11
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5 .0 SUS ITNA R IVER BASIN METEOROLOGY
Th e variab le c limatic cond it ions t hroug h t he Sus it na R iver bas in
s ign if icantly effect the gross v olume of fra zil ice generat io ,l , longevity of
the float ing s lush ,and rate of ice cover development (Fi gu re 5 .1).Th e
dom i nat ing parameters govern ing these var iab les are a ir temperature and
so lar r adi ati on.Beg inn i ng i n late September and early Octobe r fraz il ice
forms d ur ing the night on the u pper r iver near Denali .I n 1983 ,the
tempe rature of the water at th is t ime was still sl ightly above ooC .When
solar rad iat ion is el iminated and air temperatures are cold (i.e.-SoC).the
boundary layer or water surface can be supercooled and fraz il crystals
form .Th is supercooled layer is probably too th in to def ine by a
temperature gradient .The only real ev idence that it ex isted is the
presence of fine-gra ined slush ice float ing on the surface.Frazil
.generation stops soon after the sun rises,and solar rad iat ion may actually
beg in to melt the surface s lush ice even when a ir temperatures are s lightly
under OOC .Several authors ha ve observed s imilar processes (Michel 1971 ,
Newbu ry 1969).Most mat hematical analyses concern ing heat transfer and
f raz il ice generat ion do not cons ider temperatures a t the boundary layer
but only o f the en t ire water body and ad jacent air mass .
D ur ing th e f our y ears of o bse rv ati on,f raz il ice h as been o bserved to form
i n t he u pp er r i ve r reach near Dena li i n September .Th is fraz il floats to
th e s urface and fl ows downst rea m at n early the same v elocity as the water .
.T he reach between Dena li and Vee Can yon I S genera lly or iented
north /sou th a nd t he low surround ing topography a llows a long i nte rval of
so lar e xposure .Th e net f razil ice vo lume generated i n th is area i s t hus
substantia lly less than the follow ing reach from Vee Canyon to Dev il
Canyon .I n this reach ,the r iver flows west through canyons often o ver
1 ,000 feet deep .The steep cl iffs o n the south bank s ign if icantly shade
the water surface f rom the sun.From October through March ,when the
sun angle is low ,l ittle heat is ga ined from d irect short wave rad iation .
This turbulent reach probabl y loses more heat and subsequently generates
mo r-e frazi l on any given day dur ing f reeze- up than ei ther the area
- 36 -
s6/mm34
upstream of Vee Canyon or downstream of Gold Creek.This observation
is essentially qual itative since no weather stations are located w ithin the
canyo n area.The stations at Kosina,Watana and Devil Canyon are
situ.ted on the h igh plateaus on e ither side of the river and the
parameters measu red there are not representative Qf the meteorological
conditions at the water surface.
The upper Susitna River basin,north and east of Talkeetna ,was
relatively cold during September 1983 compared to average historical data
(Figure 5 .2).September 23rd marked the first day of daily mean air
temperatures below freezing at the Denali weather station.On September
25tfJ and 26th ,the min imum temperature dropped down to -12 .7°C and
-17.1°C respectively.These temperatu res were sufficiently low for
substantial frazil ice generation .On September 26th,this slush ice was
observed at Go ld Creek by ADF&G field crews and local residents .The
cold snap was temporary however,and by the last day of the month the
mean daily air temperature at Denali was again above OOC and all traces of
ice on the river had disappeared (Figure 5 .3).Based on mean da ily air
temperatures ,the total number of freez ing degree-days r'.lnged from 49 at
the Denali weather station to 6 at Talkeetna .The average h istorical
number of freezing degree-days for September is only 17 at Denali and a
at Talkeetna.This cool trend reversed during the follow ing months so
that the river freeze-up process was considerably slower than that
documented in 1982 .
The mean monthly air temperatures during October at Talkeetna ,De vil
Canyon and Watana were co lder than normal but the number of accumu lated
freezing degree-days at all the Sus itna Basin weather st.:tions were less
than the histor ical a verage (Tables 5 .1 ,5 .2,5 .3 and 5 .4).This was
pr imarily because of the widely fluctuating mean daily air temperatures and
because freezing degree-da ys (_OC)does not take i nto cons ideration the
thaw ing degree-days (_OC)in the stat istical accumu lation .Mean dail y air
temperatures at Dena li (Table 5 .5)were cons istently below f reezing with
the except ion of four days .The ice volume estimates from Gold Cree k
- 37 -
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show a steady f low of ice after October 14 (Fig ure 5 .4 and 5 .5).Ice
vo lumes r emained h igh unt il October 29,fo llowed by a sharp reduct ion
unt il November 1 .A poss ible exp lanat ion for the low ice vo lumes observed
at Go ld Creek on the 30th and 3 1 st o f October is t he deve lopment of an ice
br idge in Devi l Canyon and the temporary upstream progress ion f rom that
po int . I n 1982,th is had been observed to occur rap idly g iven a suffic ient
incomi ng ice volume .When an ice bridge develops in the Dev i l Canyon
a rea ,the ice vo lume r eaching Gold Creek i s s ign ificant ly reduced.
The d ifference between mean monthly air temperatures and the h istorical
means were even greater during November ,w ith air temperatures above
normal.The number of f reez ing degree-days accumulated i n November at
Ta lkeetna was 36 degree-da ys below the histor ical a verage .The last three
days of the month were particularly warm with mean daily air temperatures
above OOC .This was reflected by the low volume of slush ice passing
Gold C reek .
Ice volumes at Gold C reek sta yed low for the f i rst s ix days i n December
wh ile a ir temperatures g radua lly decl ined .The ma ximum ice d ischa rge for
the month of December occurred on the 12th.Ice d ischarges remained low
for the rema inder of December e ve n though a ir temperat ures were general-
ly below -lOoC .Th i s was a consequence of the gradua l f reezing o ver of
the upper river.Ice bridges were observed near Watana Creek and
Kos in a C reek .These essent iall y prevented most of the s lush from
cont inu ing downstream .The el imination of this fraz il generating zone
s harp ly reduced the v olume of ice observed at Go ld Cree k.When the
upstream o pen water area is reduced.less heat exchange t a k es place and ,
subsequently ,there is a reduct ion i n fraz il generation .With less fraz il
being formed,the entire freeze-up process slows as shown by the rate of
lead ing edge progress ion on F igure 6 .14 ,in Sect ion 6 .
January a ir temperatures fluctuated cons iderably ,reach ing a mean of OOC
on the 12t h and 13th and a low of -29°C on the 25th .Ice volumes were
low throughout the peri od of record for the month .Freeze -up at Gold
- 38 -
s6 /mm36
Creek occurred on January 14th but the lead ing edge d id not progress far
past this po int,as the slush ice produced upstream was min imal,and most
ice seemed to be carr ied underneath the ex ist ing cover.
For additional information on the meteorology program for the Susitna
Project see the Processed Climatic Data Reports (R&M 1982b,1983b).The
weather condit ions related to ice processes were d iscussed w ith more detail
in the 1983 Ice Studies report and will not be repeated here .
- 39 -
I s6 /mm37
I TABLE 5 .1
I T ALKEETNA
SUMMARY OF AIR TEMPERAT URES AND
FREEZ ING DEGREE DA YS (FOOl
I SEPTEMBER OCTOBER
Min.Max .Mean FDD Min.Max.Mean FDD
I 1.5.5 14.4 10.0 0 3.9 8 .9 6.4 0
2 .2 .8 15.6 9 .2 0 3.3 11.1 7 .2 0
I 3 .2.8 15.6 9 .2 0 1.1 8 .9 5 .0 0
4 .1.7 13 .3 7 .5 0 -3 .3 9.4 3 .1 0
5 .-1. 7 14.4 6 .4 0 -1. 1 5.0 2 .0 0
6 .-3.9 15 .0 5 .6 0 -5 .0 5.0 0 .0 0
I 7 .-2 .8 15.6 6 .4 0 -8.3 2 .8 -2 .8 2 .8
8 .5 .6 13 .9 9 .8 0 -8 .3 1.7 -3 .3 3 .3
9 .5 .6 13.9 9 .8 0 -2 .8 -1. 1 -2 .0 2 .0
I 10 .1.1 15.6 8.4 0 -1.1 ..,~0 .9 0_.Co
11.0.6 16.7 8 .7 0 -1.1 6 .7 2 .8 0
12 .5 .0 15.6 10.3 0 0 .0 6 .1 3 .1 0
I 13 .4 .4 '13.3 8.9 0 -3.9 4 .4 0.3 0
14. 3 .3 7 .8 5 .6 0 -6 .7 3 .9 -1.4 1 .4
15.-1. 1 11.7 5 .3 0 -1. 1 3.9 1.4 0
16.-2.8 15.6 6 .4 0 -2.8 2 .8 -0 .4 .4
I 17.-3 .3 13.3 5 .0 0 -1.1 6 .1 2 .5 0
18. -2 .8 12.2 4 .7 0 -3 .9 8.9 -1. 5 1.5
19.2 .8 12.2 7.5 0 -2 .8 3.3 0 .3 0
I 20 .4.4 9.4 6 .9 0 -5 .0 0.6 -2 .2 2 .2
21.6 .7 12 .2 9 .5 0 0.0 6.7 3 .4 0
22 .2 .2 11.7 10.0 0 -7 .8 3 .3 -2.3 2.3
I 23.-2 .2 5 .0 1.4 0 -1 0 .0 1.7 -4 .2 4 .2
24.-5. 6 0 .6 -2.5 2 .5 -12 .2 1.1 -5. 6 5 .6
25.-4 .4 2 .8 -0 .8 .8 -15 .6 -1.7 -8.7 8 .7
I 26. -8 .3 5 .6 -1.4 1 .4 -10 .0 -3 .9 -7 .0 7 .0
27. -7 .2 4.4 -1.4 1.4 -6.1 3 .9 -1. 1 1.1
28. -0 .6 2 .8 1.1 0 -6 .1 3.9 -1. 1 1.1
29.2.8 5.6 4 .2 0 -8.3 -0 .6 -4. 5 4.5
I 30 .5.0 10.6 7 .8 0 -6 .7 -0 .6 -3 .7 3 .7
31 .-6 .7 -1.7 -4 .2 4.2
I Mean Monthly Air Temp .6 .0 -0.6
Monthly Total 6 .1 56 .0
I Average Histor ical Mo nthly Total 0 72
I Accumu lated 6 .1 62 .1
Average Historical Accumulated 0 72
I
I - 40 -
s6 /mm38
TA BLE 5 .1
(cent ')
NOVEMBER DECEMBER
Min.Max .Mean FDD Mi n.Max.Mean :DD
1.-6.7 0 .6 -3. 1 3 .1 -2 .2 3 .3 0 .6 0
2 .-5.0 1 3 .3 -0 .9 0 .9 -8. 9 -1.1 -5 .0 5 .0
3 .-9 .4 3 .9 -2 .8 2 .8 -4.4 -2.2 -3 .3 3 .3
4 .-12.8 -3 .9 -8 .4 8.4 -4.4 -2 .8 -3 .6 3 .6
5 .-16 .7 -5 .6 -11 .2 11.2 -2 .8 -0 .6 -1. 7 1.7
6 . -2 0.0 -5.6 -12 .8 12 .8 -10.0 0 .0 -5.0 5.0
7 .-6.1 -1.7 -3. 9 3.9 -15.0 -7 .2 -11. 1 11.1
8 .-J.8 2 .8 -0 .5 0 .5 -20 .0 -13 .9 -17.0 17.0
9.-6. 1 2 .2 -2.0 2 .0 -20 .6 -11 .7 -16 .2 16 .2
10. -2 .2 1.7 -0 .3 0 .3 -12 .2 -6 .7 -9 .5 9.5
11 .-8.3 2 .8 -2 .8 2 .8 -7 .8 4.4 -6 .1 6 .1
12.-8.3 -1. 1 -4 .7 4 .7 -14 .4 -5 .6 -10 .C 10 .0
13 .-17 .8 -3 .9 -10 .9 10 .9 -14 .4 -6 .1 -10 .3 10.3
14.-17.8 -3 .9 -10. 9 10 .9 -23 .9 -13.3 -18 .6 18.6
15. -7 .2 0 .0 -3 .6 3 .6 -25 .6 -14.4 -20 .0 20 .0
16. -8.3 -2 .2 -5 .3 5 .3 -20 .0 -10 .6 -15 .3 15.3
17 .-11.7 -3 .9 -7 .8 7 .8 -11 .1 -6 .7 8 .9 8 .9
18.-11 .1 -4 .4 -7 .8 7 .8 -14.4 -5 .0 -9 .7 9.7
19.-20 .0 11.1 -1 5 .6 15 .6 -15 .5 -4 .4 -10 .0 10 .0
20.-1 8 .3 -2.8 -10 .6 10.6 -5 .0 -1.1 -3.1 3.1
21.-2 .8 0 .6 .-1.1 1.1 -5 .0 0 .0 -2.5 2.5
22.-1.1 1.7 0 .3 0 -19 .4 -2.2 -10 .8 10 .8
23.-5.0 -0 .6 -2.8 2 .8 -22 .2 -17 .8 -20 .0 20 .0
24.-15. 6 -4.4 -10. 0
10 .0 -22 .8 5 .6 -8 .6 8 .6
25. -16 .7 4 .4 -10 .6 10 .6 1 .7 7 .2 4 .5 0
26.-4 .4 -2 .2 -3 .3 3 .3 -15 .0 5 .0 -5 .0 5 .0
27 .-4 .4 0 .6 -1.9 1.9 -18.9 -12 .8 -15.9 15 .9
28.0 .0 2 .8 1 .4 0 -22.2 -18.3 -20 .3 20 .3
29 .-3 .3 3.9 0 .3 0 -25 .0 -20 .0 -22 .5 22 .5
30 .-6 .7 2.8 2 .0 0 -2 6 .1 -12.8 -19 .5 19 .5
31.-12 .8 -6 .1 -9 .5 9 .5
Mean Mon th ly Ai r Temp .-5.1 -10.1
Mont hly Total 155.6 31 8 .7
Average His tor ica l Monthly Total 191 407
Acc umu lated 217.7 53li.4
Av erage H i stor i ca l Acc umula te d 263 61('
-41 -
I s6 /mm39
I TA BLE 5 .2
I S HER MAN
SUMMAR Y OF AI R TEMPERAT URES AND
FREEZ ING DEGREE DAYS (FDD)
I SEPTEMBER OCTOBER
Min .Max .Mean FDD Min .Max .Mean FDD
I 1.5.8 12.4 9 .1 0 2 .4 7 .9 5 .2 0
z.-0 .9 15 .3 7 .2 0 -0 .3 10.3 5 .0 0
I 3.-1.5 16.5 7 .5 0 -3 .2 7.9 2 .4 0
4.-2 .3 13 .1 5 .4 0 -6.7 9.1 1.2 0
5 .-3 .6 14.2 5.3 0 -1. 1 3 .6 1.3 0
I 6.-4 .3 15.0 5 .4 0 -7.9 5 .2 -1.4 1.4
7 .-3. 7 14.7 5 .5 0 -11 .7 0 .9 -5 .4 5 .4
8.3 .8 .12.8 8 .3 0 -13 .4 1.0 -6.2 6 .2
9.4 .7 14.6 9 .7 0 -3 .4 -1.3 -2.4 2 .4
I 10 .0 .9 15.0 8 .0 0 -1.2 1.0 -0 .1 0 .1
11.1.0 15.5 8 .3 0 0 .5 7.4 4 .0 0
12.3.3 14 .8 9.1 0 0.5 4 .5 2 .5 0
I 13 .1 .5 12 .9 7.2 0 -4 .2 3 .5 -0.4 0 .4
14 .0 .1 7 .5 3 .8 0 -8.0 3.0 -2.5 2.5
15 .-3.2 11.9 4.1 0 -3 .7 3.4 -0 .2 0 .2
I 16 . -4.8 15.7 5 .5 0 -4 .6 3.1 -0.8 0 .8
17.-5 .1 12'.8 3 .9 0 -4 .4 7 .2 1.4 0
18.-4 .8 13.5 4 .4 0 -1.3 6 .5 2 .6 0
19. -3 .0 12.0 4 .5 0 -6.7 0 .2 -3 .3 3.3
I 20. 5 .0 8 .8 6 .9 0 -6 .7 0 .1 -3.3 3.3
21. 5 .9 12.2 9.1 0 -2 .9 3.8 0.5 0
22 .0.3 9 .8 5.1 0 -7 .2 5.4 -0.9 0 .9
I 23 .-2.6 3 .4 0.4 0 -11.7 3 .4 -4 .2 4 .2
24 .-3 .4 -0.6 -2.0 2.0 -12.1 1.5 -5 .3 5.3
25 .-9.2 3.7 -2.8 2.8 -13 .2 -0 .2 -6.7 6.7
I 26.-11 .6 3 .9 -3.9 3 .9 -11.4 1.7 -4.9 4.9
27. -11.1
3 .6 -3 .8 3.8 -9.3 2.6 -3.4 3 .4
28 .-0 .9 1.8 0 .5 0 -2 .7 2 .0 -0 .4 0 .4
29 .0 .2 3 .4 1.8 0 -9 .0 -2 .0 -5 .5 5.5
I 30 .2.3 10.2 6.3 0 -7 .0 0.1 -3.5 3.5
31.-6.2 -1.9 -4 .1 4.1
I Mean Monthly Air Temp . 4 .7 -1.3
I Monthly Total 12.5 64.9
Average Historical Monthly Total 0 '189
I Accumulated 12 .5 77.4
Average Histor ical Accumulated 0 189
I ?
I - 42 -
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s6/mm40
TABLE 5 .2
(cent ')
NOVEMBER DECEMBER
Min .Max.Mean FDD Min .Max .Mean FDD
1.-9.5 -0.6 -5.0 5 .0 -3.1 2 .2 -0.4 0 .4
2.-7.0 4.2 -1.4 1.4 -8.5 -2.9 -5.7 5 .7
3 .-9.4 3.5 -3 .0 3.0 -6.5 -3.4 -5 .0 5 .0
4 .-10.5 -1.8 -6.2 6.2 -8.8 -2.8 -5.8 5.8
5.-14.3 -1.4 -7.8 7 .8 -3.8 -2.4 -3 .1 3.1
6.-17.3 -8.4 -12 .8 12 .8 -10.7 -1. 5 -6 .1 6 .1
7.-10.3 -1.6 -6 .0 6 .0 -15.6 -10.7 -13 .2 13.2
8.-3.6 2 .7 -0 .4 0 .4 -20.6 -11.4 -16 .0 16 .0
9 .-3.2 4 .3 0 .6 0 -22 .9 -12 .9 -17.9 17.9
10.-3.1 2 .9 -0 .1 0 .1 -14 .5 -6. 1 -10.3 10 .3
11.-9 .1 0 .9 -4 .1 4 .1 -9 .5 -4 .5 -7.0 7 .0
12. -7 .5 -1.4 -4.4 4.4 -16 .1 -7.2 -11.7 11 .7
13.-15.4 -6 .3 -10 .8 10.8 -14.3 -5.5 -9.9 9 .9
14.-17.8 -7.3 -12 .6 12.6 -21.2 -16.0 -18.6 18.6
15.-13.9 0.3 -6.8 6.8 -25.7 -18.4 -22 .1 22.1
16.-10.6 -2.2 -6.4 6 .4 -17.7 -12.5 -15 .1 15.1
17.-15.4 -6.9 -11.2 11.2 -12 .6 -8.5 -10. 6 10.6
18.-17 .6 -6 .5 -12.0 12.0 -17 .8 -7.7 -12.8 12 .8
19.-21.2 -15.0 -18.1 18.1 -17 .5 -6 .8 -12.2 12 .2
20. -20 .6 -2.4 -11.5 11 .5 -7 .1 -3.3 -5 .2 5 .2
21.-2.0 3.4 0 .7 0 -5 .8 -2 .2 -4 .0 4 .0
22. -4 .5 0 .1 -2 .2 2 .2 -19 .8 -4 .3 -12 .1 12 .1
23 .-9.9 -3.4 -6 .6 6 .6 -21 .3 -16 .5 -18 .9 18 .9
24 .-19 .6 -7.4 -13.5 13.5 -19 .5 -9 .4 -14 .5 14 .5
25.-17.5 -6 .7 -12.1 12.1 -10 .0 0 .6 -4.7 4 .7
26. -9 .3 -4 .4 -6 .8 6.3 -17 .0 7 .7 -12 .4 12 .4
27 .-8 .8 -2 .5 -5 .7 5.7 -22 .2 13.3 -17 .8 17.8
28. -4 .1 2 .6 -0 .8 0.8 -23 .9 -20.7 -22 .3 22 .3
29.-3.4 4.0 0 .3 0 -26 .0 -21.7 -23.9 23 .9
30. -7 .0 3.4 -1.8 1.8 -27.3 -16 .7 -22 .0 22 .0
31.-16 .3 -10 .2 -13.3 13 .3
Mean Monthly Air Temp.-6.3 -12.1
Monthly Total 191 374.6
Average Historical Monthly Total 301 274
Accumulated 268.4 643 .0
Average Historical Accumulated 490 764
-43 -
I s6/mm41
I TABLE 5 .3
I DEVI L CANYON
SUMMARY OF AIR TEM PERATUR ES AND
F REEZING DEGREE DA YS (FOOl
I SEPTEMBER OCTOBER
Min.Max.Mean FDD Mi n.Ma x.Mean FOD
I 1.5.6 10.2 7.9 0 0.2 5.8 3.0 0
2. 1.0 12.1 6.6 0 0.2 7 .7 4 .0 0
I 3 .0 .6 13.0 6 .8 0 -3.0 4 .4 0 .7 0
4 . -1. 1 8 .9 3 .9 0 -4 .1 6 .6 1.3 0
5 . -3.0 11.6 4 .3 0 -1.6 2 .2 0 .3 0
I 6.-2 .1 11.4 4 .7 0 -8 .3 2 .2 -3 .1 3 .1
7.-1 0. 5 11.1 0 .3 0 -10.9 -2 .3 -6 .6 6 .6
8 .3 .8 .9 .6 6 .7 0 -13. 2 -0 .8 -7.0 7 .0
9 .3.5 11.8 7 .7 0 -5 .2 -2 .4 -3. 8 3.8
I 10. 3 .7 11.7 7 .7 0 -2.8 1.0 -0 .9 0 .9
11. 3 .2 13 .0 8 .1 0 0 .1 7 .7 3 .9 0
12.3.7 11 .5 7 .6 0 -0 .2 3.8 1.8 0
I 13.2 .7 11.0 6 .9 0 -5.6 1.5 -2 .1 2 .1
14.2 .6 6 .4 4 .5 0 -10 .0 -0 .5 -5.3 5 .3
15.-1.6 8 .9 3 .7 0 -7 .0 0 .8 -3 .1 3 .1 .
I 16.-3 .0 12.5 4 .8 0 -8.9 0.4 -4 .3 4 .3
17.-2.6 10 .0 3 .7 0 -5.1 5 .1 0.0 0
,18 .-8. 4 11.3 1.5 0 -1. 1 3 .4 1.2 0
19.-0.2 9 .4 4 .6 0 -3 .5 -0.7 -2 .1 2 .1
I 20 .3 .6 8 .7 6.2 0 -3.5 -0.5 -2.0 2.0
21.5 .7 11.3 8 .5 0 -2.0 4.3 1.2 0
22.-0 .9 7.3 3.2 0 -3 .5 3 .7 0 .1 0
I 23 .-5 .8 -0 .1 -3.0 3 .0 -8 .7 0.9 -3 .9 3 .9
24 .-9 .3 6.4 -1 .5 1.5 -10.9 -1.6 -6 .3 6.3
25 .-6.7 -0.8 -3.8 3 .8 -12.5 -3 .3 -7.9 7 .9
I 26 .-8 .9 0.0 -4 .5 4 .5 -9.2 -1. 6 -5 .4 5 .4
27 .-9 .0 0 .6 -4 .2 4.2 -28.4 -0. 2 -14 .3 14.3
28. -2 .8 2 .1 -0 .4 0 .4 -4 .0 0 .1 -2.0 2 .0
29 .0 .1 3.7 1.9 0 -10 .0 -2 .0 -6.0 6 .0
I 30 .2 .4 7 .3 4 .9 0 -5.2 -1.4 -3.3 3 .3 .
31.-8.2 -3 .5 -5. 9 5 .9
I Mean Mon thly Air Te mp.3 .6 -2 .5
I Monthly T otal 17.4 95 .3
Average Historical Monthly Tota l 5 95
I Accumulated 17 .4 112.7
Average Historical Accumulated 5 100
I
I -44 -
s6/mm42
TABLE 5 .3
(cen t ')
NO VEMBER DECE MBER
Min .Max .Mea n FDD Min .Max . Mean FDD
1.-10. 7 0.2 -5 .2 5 .2 -2 .6 2 .1 -0 .2 0 .2
2 .-5.3 1.8 -1.8 1.8 -5.5 0 .7 -5 .1 5 .1
3.-10 .3 0 .4 -5 .0 5.0 -6 .7 3 .4 -5 .0 5 .0
4.-9.8 0 .8 -4 .5 4.5 -6.7 -4.7 -5 .7 5 .7
5 .-9 .5 -3 .0 -6 .2 6.2 -5 .5 ·-2 .5 -4 .0 4 .0
6 .-12 .3 -6.7 -9.5 9 .5 -8 .4 -2.1 -5.3 5 .3
7.-7.5 -2.9 -5.2 5 .2 -7 .0 -3.8 -5.4 5 .4
8 .-3.0 1.3 -0.8 0 .8 -10 .6 -2.9 -6 .8 6 .8
9.-5.3 2.2 -1.6 1.6 -13.6 -2 .6 -8.1 8 .1
10.-5.4 0 .2 -2 .6 2 .6 ,-16 .3 -8 .8 -12 .6 12 .6
11.-6.7 0 .7 -3 .0 3 .0 -11.8 -7 .1 -9.5 9 .5
12. -7.2 -4 .5 -5.8 5 .8 -14.3 -8 .9 -11.6 11.6
13. -13.3 -5 .7 -9 .5 9 .5 -1 1.8 -8 .5 -10 .2 lC.2
14.-12 .8 -8 .4 -10. 6 10.6 -22.2 -18 .3 -20 .3 20 .3
15.-13.3 -0 .1 -6.7 6.7 -26 .7 -23 .3 -25.0 25.0
16.-12 .0 -3.4 -7.7 7 .7 -21.1 -17 .2 -19 .2 19.2
17.-14 .5 -8.3 -11.4 11.4 -15 .0 -5 .6 -10 .3 10.3
18.-16 .0 -8 .6 -12 .3 12.3 -1 4.4 -6 :7 -10 .6 10.6
19 .-17 .3 -12.4 -1 4.8 14 .8 -16.7 -7 .8 -12.3 12.3
20 .-16 .6 -4 .6 -10. 6 10.6 -8 .0 -3 .8 -5 .9 5 .9
21. -4 .4 1.9 -1.2 1.2 -6 .4 -2 .9 -4 .7 4.7
22 .-6.8 0 .2 -3 .3 3 .3 -15.6 -11.1 -13.4 13 .4
23.-7.9 -4.6 -6 .2 6 .2 -22 .2 -17.8 -20 .0 20.0
24. -13 .5 -5.6 -9 .6 9 .6 -20 .0 -9 .4 -14.7 14 .7
25.-10 .2 -9 .0 -9.6 9 .6 -14.4 1 .3 -6.6 6 .6
26 .-9 .4 -5.5 -7 .4 7 .4 -11. 9 -8 .2 -10 .1 10.1
27 .-9 .2 -3 .2 -6 .2 6 .2 -15.3 -8 .2 -11.8 11.8
28.-4 .5 0 .9 -1.8 1.8 -23 .3 -21 .1 -22.2 22 .2
29 .-1.4 3 .5 1 .0 0 -28 .9 -19 .4 -24 .2 24 .2
30 .-1.3 2 .8 0 .8 0 -26 .7 -16.7 -21.7 21.7
31.-24 .4 -12.2 -18 .3 18.3
Mean Monthly Air Temp.-5.9 -1 1.6
Monthly Total 180 36J .8
Average Historical Monthly Tota l 222 391
Accumula ted 292 .8 653.6
Ave rage Histor ical Accumulated 322 71 3
-45 -
I s6 /mm43
I TA BLE 5 .4
I WATAN A
SUMMAR Y OF AI R TEM PERATU RES AND
FRE EZ ING DEGR EE DA YS (F DD)
I SEPTEMBER OCTOBER
Min.Max .Mean FDD Min .Ma x.Mean FDD
I 1.1.6*0 -0 .9*0 .9
2 .1.1* 0 -0 .3*0 .3
I 3 .1.4 6 .1 3 .8 0 -1 .9*1.9
4 .4.4 10.0 7 .2 0 -3 .2*3.2
5 .-0 .9*0 .9 -3 .9*3 .9
6.-1 .4*1.4 -5 .3*5.3
I 7 . 2 .3 8 .3 5 .3 0 -7.2*7 .2
8 .3 .2 .3 .4 3 .3 0 -7 .6*7 .6
9 .3 .6 8 .8 6 .2 0 -6 .7*6 .7
I 10 .4 .2 11.0 7 .6 0 -4 .7 * 4 .7
11. 1.6 11 .1 6 .4 0 -3.4*3.4
12. 2 .6 11.2 6 .9 0 -3 .2*3 .2
I 13 .1.2 8 .3 4 .8 0 -5.1*5 .1
14. 0 .1 5 .2 2 .7 0 -6 .3* 6 .3
15 .0 .1 7 .6 3 .9 0 -4.3* 4 .3
16.-3.2 10 .7 3 .8 0 -5 .6*5 .6
I 17.-4 .7 10 .0 '2.7 0 -0.8 0 .9 0 .1 0
18 .-6 .7 8.6 1.0 0 -5 .1 0 .5 -2 .3 2 .3
19.1.6 7.2 4.4 0 -6 .3 -2 .7 -4.5 4 .5
I 20.2.7 8 .5 5 .6 0 -5.2 -2 .7 -4.0 4 .0
21.4 .5 8 .3 6.4 0 -3 .2 1.8 -0.7 0 .7
22 .1.6* 0 -4 .6 -0 .1 -2 .4 2 .4
I 23 .-4 .3*4 .3 -7.1 -1.9 -4 .5 4.5
24 .-7 .0 *7 .0 -1 0 .5 -2 .4 -6 .5 6 .5
25 .-5 .9*5 .9 -9 .4 -6.7 -8 .1 8 .1
26.-6 .3*6 .3 -9.1 -4 .6 -6.9 6 .9I27.-6 .3*6 .3 -11 .8 -2 .7 -7.3 7.3
28.-4.5*4 .5 -8.3 -2 .9 -5.6 5.6
29.-2.4*2.4 -9 .6 -1.3 -5 .5 5 .5
I 30 .0 .1*0 -6.0 -2 .3 -4 .2 4 .2
3 1.-11 .9 -3 .6 -7.8 7 .8
I Mean Monthly Air T emp .-0 .31 -4.5
I Mon thly Total 39 .0 139.9
Average Hist orical Monthly T otal 13 127
I Accumulated 39 .0 178.9
Average Historical Acc umulated 13 140
I *Est imated values from linear correlat ion with t he Ta l keetna Weathe r Station.
I - 46 -
s6/mm44
TABLE 5.4
(cen t ')
NOVEMBER DECEMBER
Min .Max .Mean FDD Min .Ma x .Mea n FDD
1.-13 .4 -2 .3 -7 .9 7 .9 -4.2 0.3 -2 .0 2 .0
2 . -10.2 -1.8 -6 .0 6.0 -6 .3 -2.4 -4 .4 4.4
3.-10.6 -1.8 -6 .2 6.2 -10.6 -6 .1 -8.4 8 .4
4 .-11 .9 -3 .3 -7 .6 7.6 -8.6 -7 .0 -7 .8 7 .8
5.-12.0 -5 .1 -8 .6 8.6 -7.9 -3 .9 -5.9 5 .9
6.-14 .8 -7 .7 -11.3 11.3 -6.4 -4 .2 -5 .3 5 .3
7 .-11 .6 -6 .8 -9 .2 9 .2 -8.7 -5 .1 -6 .9 6 .9
8. -7 .0 -0 .2 -3 .6 3 .6 -14.5 -8. 6 -11 .6 11.6
9.-8 .4 -1.0 -4 .7 4 .7 -20.2 -13 .6 -16 .9 16.9
10.-8 .4 -4 .1 -6 .3 6 .3 -19 .2 -13. 7 -16.5 16.5
11.-9'.9 -2 .5 -6.2 6 .2 -15 .2 -10 .3 -12 .8 12 .8
12.-12.3 -6 .8 -9.6 9 .6 -15 .2 -1 0.4 -12.8 12.8
13. -15.6 -7 .1 -11.4 11.4 -14 .7 -12 .6 -13.7 13. 7
14.-1 5 .1 -9 .2 -12 .2 12.2 -22.7 -15 .3 -19.0 10.0
15.-15 .2 -6 .6 -1 1.4 11 .4 -24.3 -17.2 -20 .8 20 .8
16 .-15 .0 -8 .6 -1 1.8 11.8 -21 .9 -18 .4 -20 .2 20 .2
17 .-15 .9 -7 .8 -11 .9 11.9 -19 .7 -15.0 -17 .4 17.~
18.-18 .1 -10 .2 -14 .2 14 .2 -16 .7 -9.2 -13.0 13.0
19.-18.0 -10.1 -14 .1 14.1 -14 .0 -8.0 -11 .0 11 .0
20.-18.5 -6.7 -12.6 12 .6 -10.2 -6.3 -8 .3 '8 .3
21.-6. 2 0 .9 -2 .7 2 .7 -13 .0 -5.5 -9.3 9 .3
22.-9. 1 -0.8 -5.0 5.0 -16 .9 -12 .6 -14 .8 14 .8
23.-10 .6 -6.4 -8.5 8 .5 -17.2 -13.5 -15.4 15 .4
24. -14 .5 -7 .5 -11.0 11.0 -17.7 -1.7 -9 .7 9 .7
25 .-14 .5 -11 .0 -12.8 12.8 -13 .9 -3 .6 -8 .8 8.8
26 .-11.7 -7 .5 -9 .6 9 .6 -13. 4 -6 .2 -9 .8 9 .8
27.-9 .6 -5.1 -7 .4 7.4 -18. 1 -7 .9 -13 .0 13 .0
28 .-6.8 0 .8 -3 .0 3.0 -22.7 -17.1 -19 .9 19 .9
29 .-1.6 1.8 0 .1 0 -22.7 20.0 -21.4 21.4
30 .-2 .5 0 .5 -1.0 1.0 -26 .7 -21.4 -24 .1 24 .1
31.-22 .2 -10.9 -16.6 16.6
Mean Monthly Air Te mp .-8 .3 -13.4
Month ly Total 247 .8 397 .5
Avarage Histor ical Monthly Total 279 468
Accumulated 426 .7 824 .2
Average Histo rical Accumu lated 419 887
-47 -I
--..•.-~-
I s6/mm45
I TABLE 5 .5
I
DENALI
SUMMARY OF AIR TEMPERATURES AND
FREEZING DEGREE DAYS (FDD)
I
SEPTEMBER OCTOBER
I Min .Max .Mean FDD Min. Max.Mean FDD
1.0 .1 4 .1 2 .1 0
I 2. -0.1 7 .4 3.7 0 -1.0 4 .8 1.9 0
3. -0 .6 9.4 4.4 0 -5 .3 0 .3 -2 .5 2.5
4.0.4 5.3 2.9 0 -8.4 1.1 -3.7 3 .7
5 . -1.5 5.4 2.0 0 -5.4 0.1 -2.7 2 .7
I 6 .-0.9 6.6 2.9 0 -8.8 -2.0 -5.4 5 .4
7 .-0 .9 8 .0 3 .6 0 -16.5 -5 .1 -10.8 10.8
8 .1.1 7 .6 4 .4 0 -18 .9 -6 .6 -12 .8 12.8
I 9.2.6 9.3 6 .0 0 -9 .0 -2 .5 -5.8 5.8
10.0.1 10.0 5.1 0 -2 .3 6.0 1.9 0
11 .-2.5 10.3 3 .9 0 0 .4 4.9 2 .7 0
I 12 .2 .4 10.1 6 .3 0 -1.8 2 .5 0 .4 0
13.0.1 8 .0 4.1 0 -4 .6 -0 .3 -2 .5 2 .5
14 .0 .6 7 .4 4 .0 0 -9.5 -1.2 -5 .4 5.4
15.-2 .5 6 .0 1.8 0 -13 .6 -1 .0 -7 .3 7 .3
I 16. -2 .0 8 .0 3 .0 0 -16 .0 -3 .6 -9.8 9 .8
17."4 .5 9.4 2 .5 0 -8.5 0 .1 -4 .2 4 .2
18 .-5 .2 7 .9 1.4 0 -6 .3 0.1 -3. 1 3.1
I 19. 0 .1 6 .8 3 .5 0 -10 .5 6 .3 -2 .1 2 .1
20 .0 .7 9 .3 5.0 0 -10 .7 -2 .0 -6.4 6 .4
21. 3 .3 7 .3 5.3 0 -6 .9 1.7 -2 .6 2 .6
I 22 .-4.4 5 .2 0.4 0 -8 .6 -0.8 -4 .7 4 .7
23. -8 .2 -4 .8 -6 .5 6 .5 -12 .0 -0 .5 -6 .3 6 .3
24. -1.0.0 -7 .6 -8.8 8 .8 -14 .7 -4 .3 -9.5 9 .5
25.-12.7 -5 .0 -8 .9 8 .9 -12.0 -9 .6 -10 .8 10.8
I 26.-17.1 -5.5 -11 .3 11 .3 -13.7 -3 .7 ·-8.7 8 .7
27 .-15.7 -3 .7 -9.7 9 .7 -9 .6 -1. 7 -5 .7 5 .7
28 .-4 .8 0.7 -2.1 2.1 -9.4 -1.5 -5.5 5 .5
I 29. -4 .8 0.7 -2 .1 2 .1 -10.8 -2 .5 -6.7 6 .7
30 .3.3 7 .3 5.3 0 -6 .1 -2 .5 -4 .3 4 .3
31.-12.7 -1.3 -7 .0 7 .0
I Mean Monthly Air Temp .0 .7 -4 .8
I Monthly Total 49 .4 156
Average Historical Monthly Total 17 192
I Accumulated 49 .4 205.7
Average Historical Accumulated 17 209
I
I - 48 -
------~-
s6/mm46
TABLE 5 .5
(cent ")
NOVEMBER DECEMBER
Min.Max .Mean FDD Min .Max .Mean FDD
1. -13 .0 -6 .0 -9 .5 9.5 -4 .9 -0 .8 -2.9 2.9
2 .-12 .7 -2.4 -7 .6 7.6 -7.5 -2 .0 -4.8 4.8
3 .-19 .4 -7 .5 -13 .5 13.5 -11.7 -3 .1 -7.4 7.4
4 .-20 .5 -11.7 -16 .1 16.1 -10 .8 -6 .2 -8.5 8.5
5 .-17 .2 -9 .5 -13 .4 .13 .4 -9 .3 -5.4 -7.4 7 .4
6. -20 .8 -13.4 -17 .1 17 .1 -7.0 -6 .5 -6 .8 6 .8
7 .-14.9 -6.6 -10 .8 10.8 -7.1 -5 .3 -6 .2 6 .2
8 .-11. 9 -2 .1 -7.0 7.0 -12.6 -5.4 -9.0 9.0
9 .-14.4 -3 .8 -9.1 9.1 -14.0 -12.5 -13 .3 13.3
10.-16.8 -6 .8 -11.8 11.8 -17.2 -14.4 -15 .8 15.8
11.-15 .7 -8 .1 -11. 9 11.9 -16 .6 -16 .6 -16 .6 16.6
12.-16.0 -8 .2 -12.1 12.1 -16 .1* 16.1
13.-20. 5 -12 .0 -16 .3 16 .3 -17 .1*17 .1
14.-20.8 -15 .9 -18 .4 18.4 -23.1*23 .1
15. -24 .3 -1 6.8 -20 .6 20 .6 -25 .1*25 .1
16.-19.4 -9 .4 -14 .4 14 .4 -24 .4*24.4
17.-21 .9 -17 .8 -19 .9 19 .9 -21 .3*21.3
18.-21 .2 -14 .7 -18 .0 18. 0 -16 .3*16.3
19.-22 .0 -7 .8 -14.9 14..9 -14 .1*14.1
20. -1 6. 9 -3.5 -10.2 10.2 -11.1*11. 1
21. -2 .8 2 .6 -0.1 0.1
-12.2*12.2
22.-11.6 -1.1 -6 .4 6.4 -18 .4*18.4
23.-16.0 -5 .0 -10 .5 10 .5 -19 .0*19.0
24. -21 .8 -8 .5 -15.2 15 .2 -12.6*12.6
25.-17.7 -12 .1 -14.9 14.9 -11 .6*11.6
26 .-18 .3 -11 .8 -15 .1 15.1 -12.7*12.7
27.-16 .1 -7.6 -11.9 11.9 -16 .3*16 .3
28 .-10.6 4 .2 -3 .2 3.2 -24 .1*24 .1
29.-2 .1 5.0 1.5 0 -25.8*25 .8
30 .-5 .3 0.9 -2 .2 2 .2 -28.8*28 .8
31.-20. 4*20 .4
Mean Monthly Air Temp.-11.7 -15 .1
Monthly Tota l 352 .1 469 .2
Average Historical Monthly Total 376 627
Accumulated 557 .8 1027 .0
Average Historical Accumulated 585 1212
* Estimat ed v alues f rom linear correlat ion with Watana Weather Stati on.
-49 -
500
DENALI
DEC
IJBMlU·!M:C~
SUSITNA JOI NT VENTURE
NOV
MONTH
FIGURE 5.1'
50
OCT
SUSITNA RIVER BASIN
FREEZING DEGREE (OC )DAYS
SEPTEMBER -DECEMBER 1983
fI)400 WATANA>-~SHERMAN
0--DEV IL CANYON
(,)-~
TALKEETNA
~300a::
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R&M CONSUL.TANTS,INC.
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-1983
-.,.-AVERAGE HISTOR ICAL
(19 8 2 ONLY)
--1983
---AVERAGE HISTOR ICAL
(1940 -1982)
OECOCTNOV
MONTH
L.OCAT ION :SHERMAN
OPERATOR :RaM CONSUL.TANTS.I NC.
-,
'\
'\
'\
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~""..................
......"""---------
SEP
SUSITNA RIVER BASIN
MEAN MONTHLY AIR TEMPERATURES
1983 and HISTORICAL
L.OCATION:TAL.KEETNA AIRPORT-
OPERATOR :NATIONAL.WEATHER SERVICE
o
10
-10
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R&M CONSULTANTS,INC.
......,....._••0000D••.,..~NN.__""_v ...o••
OCT NOV
MONTH
FIGURE 1.2
51
DEC
SUSITNA JOINT yENTURE
10
u•
1&1 0II:
:;:)
~
~
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1&1a..
2
1&1 -10~
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SUSITNA RIVER BASIN
MEAN MONTHLY AIR TEMPERATURES
1983 and HISTORICAL
LOCATION:DEVIL CANYON
OPERATOR:RaM CONSULTANTS,INC .
--1983
-- - AVERAGE HISTOR ICAL
(1980 -1982 )
-20 ....L..-,.----,-.-_
SEP OCT NOV
MONTH
DEC
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1&1 0
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:;:)
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LOCATION:WATANA
OPERATOR:RaM CONSULTANTS,INC.
-1983
AVERAGE HISTORICAL
(1980 -1982 )
-20 ....I....----r-------.-------r-----..------
SEP
R&M CONSULTANTS,INC••,..1......1I.~...T........""'......."."'."0-.
OCT NOV
MONTH
FIGURE 8.2
CONTINUED
DEC
SllSlTNA JOINT "CNDJAC'
-20 ------r----......,.----....,....-----=~----
SUSITNA RIVER BASIN
MEAN MONTHLY AIR TEMPERATURES
1983 and HISTORICAL
DEC
~·IEl1J~~~W
SUS/TNA J(]/NT VENTIIRE
--1983
---AVERAGE H ISTOR ICAL
(1980 -1982 )
.FIGURE 11.2
CONTINUED
53
LOCATION :DENALI AT SUSITNA LODGE
OPERATOR:RaM CONSUI.TANTS,INC .
OCT NOV
MONTH
I~l
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1&1 0
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et
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s 6/mm47
I
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Oc t obe r 5 , 1983.S lu sh
a nd u pp e r riv e r area
e xpo s ure thi s ice usua lly
FIGUR E 5 .3
ic e u sually beg ins fl owin g a t t h e De nali Highw a y br idge
i n Se p tembe r .Beca u se o f th e i ni t ial long souther-n
me lts befo re entering the midd le r iv er .
I
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41.
FI GURE 5 .4
O ctob er 17 ,1983 .Low air t emp erat ures a nd minimal s ol a r r ad iat ion i nflu enc e the
w ater su rface i n th e up per r i ver ca nyon s .These f act ors tog eth er wi th hi g,
tu rb ulen ce gen era tes large v olumes o f fr azi l s l ush i n October .
I -54 -
S US /T N/-J O IN T V ENTURE
I
I
I
I
I
I
I
I
I
I
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I
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I
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s6 /mm48
FIGURE 5 .5
October 17, 1983 . S lush ice that dr ifts i nto low velocity areas such as fl ow
margi ns a nd edd ies f reezes i nto border ic e.
-55 -
SUSfTN~J OINT VENTURE
••••••••••••••
••
•••
I
s6 /mm49
6 .0 LOWER R IVER ICE REGIME
6 .1 Freeze-up
On the morn ing of October 26 ,1983 an ice bridge formed at RM 9.
Th is ini t iated a continuous ice co ver progression upstream .
Co ns istent ly s ubstantial volumes of frazil ice had not been car r ied
into the lower Sus itna prior to October 23 as mean da ily a ir tempera-
tures at Ta lkeetna remained relat ive ly wa rm.The majority of the
f raz il ice generated between Watana and Dena li p robably me lted en-
route to the lower basin (Figure 6 .1).On October 17 ,slush ice
f lowed through the middle and lower r iver depos iting along flow
marg ins where it qu ickly froze i nto border ice (F igure 6.2).Side
channels that were beginning to dewater also collected slush ice when
the rafts grounded in the shallows (Figure 6 .3).From October 23
until October 26 slush ice floes were est imated to cover 60%of the
open water surface area on the Yentna River and about 40%on the
Sus itna .Th is interval was marked by Ta lkeetna min imum da ily a ir
tem;:>eratures less than or equa l to DoC ,wh ich was suffic iently cold to
ma inta in h igh ice concent rations down to RM 9.
Below the Yent na River confluence the Susitna water veloc ity de-
creases as the channel gradient drops from about 3 ft/mi to 1 .5 ft/mi .
Th is was ev ident on October 25 by constantly i ncreasing ice floe
concentrations on the water surface (F igure 6.4).The estimated
concentration below the Yentna confluence increased from 60 -70%
areal coverage at Sus itna Station to 90%at RM 15 and 100%at RM 9
(Figure 6 .5).
The t ida l f luctuations i n Cook I nlet have a s ign if icant i nfluence on the
water velocity and stage .The principal factor that governs when the
moving ice cover stops to form an ice bridge may be a h igh tide
cycle .Tidal fluctuations in Cook Inlet are often over 25 feet .A
high tide can cause a backwater effect to extend at least 13 miles
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upstream .Th is backwater effect alters normal stream flow by
elevat ing the water level and reducing velocity .Quantif icat ion of the
effect of t ides on veloc ity and ice movement may be requ ired for
future attempts to forecast a lower river freeze-up schedule .
The remaining critical force acting on the moving ice cover is fr iction
aga inst the banks or border ice along the bank .The fr ict ional shear
between the bank and slush ice floes decreases the ice velocity by
exceeding the shear force exerted by the flowing water .When these
counteracting forces are equal then the slush ice movement stops
(F igure 6.6).The meander at RM 9 forces the ice floes to contact
the outs ide bank .At a h igh tide the result ing backwater further
reduces the water velocity a nd with high lee concentrations and cold
air temperatures bridging is likely to occur.Cold air temperatures
are necessary to quickly freeze the ice in place .Upstream ice cover
progress ion by accumulating ice floes can beg in as soon as the slush
ice velocity slows (F igure 6 .7).The h igher upstream velocity of
i ncoming slush causes a greater volume of slush to accumulate against
the upstream edge than can be expelled from the downstream end.
Therefore,with a low channel gradient and slow water velocity the
ice cover "advance s"upstream by j uxtapositionin g.Th is process
refers to ice accumulating on the water surface s imply by contact w ith
other floes.Juxtapos itioning continues until higher water .veloc ities
are encountered and ice floes contacting a fixed cover are crushed or
become entra ined and swept under the leading edge (Figure 6 .8).
Ice displaces water acco rding to Archimedes princ iple .A f i xed ice
cover also imparts a frictional resistance to flowing water.Together
these two processes cause an increase in water level (F igure 6 .9 and
6 .10).The increase in water level ,called staging,is required to
s low water veloc it ies to such a po int that ice f loes are not swept
beneath the leadi ng edge of the ice cover .The maximum stag ing i n
segment 5 was about 2-3 feet with ice th ickness averag ing 3 feet i n
1983 .This ice th ickness refers to the total of solid surface ice
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(f rozen s lus h )and the un derlying loose s lush .Air tempe rature
contro ls the t h ick ness of t he so lid ice fract ion s imply by continually
freez ing add itional slush ic e.If the underly ing slush ice is removed
by erosion then growth of the sol id surface ice layer slows
s ignificantly .
T he f irst 19 miles of segment 5 has lower wa ter ve loc ities th an t he
reach near Sus itna Stat ion at RM 23 .The veloc ities in t he uppe r
reach p reve nted ice cover progress ion by s imple juxtapos ition and
mechan ical t hic ken ing of t he co ver occu rred f or approx imately the last
five miles up to RM 27 .Th is process of th icken ing has been
observed to occur after the slush ice cover is in place .The
frictional shear between high velocity water and the f ixed ice creates
an unstable cond it ion ,which can cause a portion of the ice co ver to
sh ift .Th is sudden movement upsets the stability of adjacent ice and
i n seconds the entire local cover is movi ng downstream and
consol idat ing.A cha in reaction of th is .type has been observed to
effect ove r 2 ,000 f eet of ice cover .Compress ion of u nco n solidated
s lush ice dur ing this move causes the total th ickness to i ncrease .
The ice cover may a lso be shoved laterall y,creating parallel r idges
along the banks as the slush contacts the channel bottom.Several of
the ice compression phases were timed to last more than 8 minutes,
which brought the leading edge downstream about one-half mile and
increased the stage about one foot.
Ae r ia l observations noted that the Yentna R iver often contributed
about 50-60'},of t he tota l estimated ice volume below the con fluence i n
1983 .On November 1 ,the ice front had passed t he confluence and
sp l i ~.one lead i ng edge go ing u p the Sus itna River and another go ing
up t he Yentna River.One day later the ice front on the Yentna was
7 miles upstream wh ile the lead ing edge on the Sus itna was 3 miles
above the confluence (Table 6 .2 and Figure 6.11).The faster
progression rate on the Yentna River was due to its morphological
characteristics .The Yenta is generally narrower ,shallower and has
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fewer channels compared to the Susitna in Segment 4.The slower
water velocit ies also permitted less ice thicknesses and therefore less
ice volume to develop a stable cover .
Prior to the freeze-up of segment 5,Alexander Slo ugh had dewatered
when decreasing mainstem flows dropped below the critical level to
overtop the entrance .Th is s ide channel was dry from approx imately
September 17 until October 27 (Figure 6 .12).On October 27 the
lead ing edge was located at RM 15 ,just 4 miles downstream from the
side channel entrance .The staging effect by the ice cover was
sufficient to flood the channel (F igure 6 .13).The flow ing water
removed much of the snow in the side channel but also inundated the
snow cover along the flow margins (F igure 6.14).This qu ick ly froze
so l id,producing a stranded ice cover over the banks.The flow ing
op-en water in Alexander Slough requ ired more than four add itional
weeks to freeze,primarily because the stage had not increased
e nough over the entrance to allow passage of slush ice.The slush
icre rafts were approximately 2-3 feet thick.Unless the stage in-
creased by that value above the bottom elevation of the channel
entrance the floes could not drift into the side channel.The
estimated depth of water over the channel entrance at maximum stage
was about 1 foot so the ice rafts merely grounded a short di stance
from the main channel .No slush ice cover progress ion was ,
therefore,observed in Alexander Slough but rather a gradual closure
of the open water by laterally grow ing borde r ice.
On November 1 ,1983 the leading edge was at RM 31 .5 hav ing pro-
gressed more than 16 miles in f ive days .By November 4 the ice
front had passed the confluence of the Deshka River at RM 40.5.
The max imum stage increase measured at the entra nce to Kroto Slough
(RM 40 .1)was 3 .9 feet (.Table 6 .1).This was suffic ient to overtop
the slough with a flow depth of 1 .5 feet at the entrance but no ice
floes could enter due to th icknesses of about 2 feet .The elevated
ma instem stage also effected the Desh ka River by creating a
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backwater zone which extended about 2 miles upstream.The surface
water velocit ies on the Deshka were reduced enough to allow Susitna
ice floes to be pushed up the Deshka for about 100 feet.Slush ice
drift ing down the Deshka river encountered this ba rrier to f low and
an upstream advance by accumulating ice was i nitiated .The'Deshka
has low water velocities and the slush ice advanced by juxta-
position ing,quickly freez ing into an ice cover .This developing cover
was not tracked further than 2 miles.
On Il o vember 5 the ice c over progress ion entered segment 3 (Delta
Island s).T he leadi ng edge spl it,and ice fronts advanced separately
up the east and west channels.The east channel ice cover pro-
gressed more slowly ,poss ibly due to the i nfluence of Little Willow
Creek and Willow Creek,which may have diluted the ice
concentration .At RM 50 on the east channel the combined f lows from
these tributar ies enter the Sus itna via a short side channel.The
advan c ing ice cover caused stage i ncreases h igh enough to i nundate
the snow cover over the Willow Creek gravel fan (F igure G.15).T h is
saturated snow then froze i nto an ice cover ;however,the water
course from Willow Creek was not altered .The measured stage
increased about 3 feet dur ing the ice front advance.Slush ice from
th e Sus itna d id not encroach on the creek confluence .The stage
increase measured at the entrance of a side channel near RM 48 on
the west channel was about 2 .5 feet .This channel was flooded but
no slush ice entered.The Susitna ice cover progressed through the
Delta Islands and converged near RM 51,then cont inued to proceed
upstream into segment 2.
Segme nt 2 contains more secondary channels w ith in a broad g ravel
and sa nd floodp lain than e ither segments 4 or 5 .The primary or
ma in channel i s relat ively shallow at freeze-up and when the .water
level r ises a w ide area i s generally flooded.The ice floes remain
conta ined with in the main channelm,s ince water depth is not
sufficient to float them laterally out of the tha lweg .As the ice
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cover proceeded through Segment 2 i n 1983 a large port ion of the
flood pla in was inundated .The saturated snow eventually froze
solid,creating an ice cover but without the hummocked appearance of
the main channel slush ice cover .
Most of the side channel complexes through segment 2 were flooded
during ice cover progress ion .Existing ice over isolated pools was
immed iately broken up and washed down the side channel when the
staged ma instem overtopped the channel entrances .Ma instem s lush
ice was observed to accompany the surge through the side channel at
RM GO.The slush ice and ice debris occasionally accumulated i n small
jams a short d istance below the side channel entrances but usually
were carried back out to the mainstem..A maximum ma instem stage
increase of 3 feet was measured near the mouth of Kashwitna River
(RM GO)on November 11 (Figure 6 .16 and 6 .17).
On November 9 the leading edge was at RM 66 ,but the new ice cover
remained unstable due to warm air temperatures that prevented the
slush from freezing .This was apparent by the quickly deter iorating
ice cover below the leadi ng edge .An open lead had formed from RM
62 to RM 65.
The leading edge con tinued to advance at an average rate of 2 miles
per day even though the channel grad ient gradually increases beyond
RM 66 and more ice was required to produce a suffic iently stable
cover .The effects of ma instem stag ing were not evident to a s ignifi-
cant degree at the mouths of e ither Sheep Creek or Goose C reek .
Sheep Creek dra ins i nto a side channel that extends from RM 62 to
RM 67 (Figure 6 .18).Through this reach the mainstem i s along the
west ban k and since the side channel comp lex is .on the east ban k ,it
was the refore not affected by backwater or o vertopp i ng.Goose
Creek enters a s ide channel that runs from RM 69 to RM 72 (F igure
6 .20).This s ide channel was also not flooded or affected by
backwater when the mainstem water level staged (F igure 6 .21).The
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stage at these tributary mouths did i ncrease sl ightly due to another
phenomenon related to ma instem stage .The approx imate 0.4 foot
increase in water level i n the pool below the Goose Creek mouth
(F igure 6 .25)was possibly due to a general increase i n the local
ground water table wh ich may be associated with staging on the
mainstem .This is simila r to water level fluctuat ions in ground water
wells ad jacent to the ma instem at Slough 9 during freeze -up (Figure
6 .22).This inc rease at Goose Creek and Sheep Creek occur red
concurrently with the ice cover advance on the ma instem opposite
these tributaries .
The mouth of Montana Creek (Figure 6 .23)was s ign ificantly
i nfluenced by the staging process .The existing channel had steadily
degraded since the ma instem water level receded.The absence of an
extens ive backwater area resulted i n h igher tributary velocities at t he
mouth and subsequently more downcutting than during high ma instem
flows .Montana Creek had therefore become entrenched in the alluvial
fan.Heavy anchor ice deposits had accumulated on the substrate and
a large ice dam had deve loped about 200 yards above the confluence
by November 10 .When the ice front approached RM 73,2 miles
downstream of the confluence,the mainstem stage adjacent to Montana
Creek i ncreased by 1 foot and created a backwater zone that flooded
the tributary channel and ice dam .A maximum stage increase of 7.1
feet was measured on November 18,and most of the confluence area
was i nundated (Figure 6.24).The snow .cover was flooded and
subsequently formed ice. An addit ional 2 feet of staging would have
been requ ired to completely overtop the alluv ial fan .The backwater
zone extended upstream beyond the Parks Highway bridge and was
ev ident by fractu red border ice and flooded snow at Montana Creek
Lodge.
Ice th icknesses were measured adjacent to the Montana Creek con-
fluence (RM 77)in late January (Table 6 .3).The total thickness
averaged 6 .8 feet with a minimum of 1 .3 feet and a max imum of 7 .0
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feet .The channel grad ient is relattve tv steep i n th is area and the
ice cover rema ined unstable.After the i nit ial progress ion through
th is reach ,an open lead appeared from RM 71 to RM 85.This lead
eventually began to freeze over when entrained frazil ice floated and
accumulated at the lower end and along the sides .This secondary
progress ion stalled near RM 81 in February 1984 and open water
remained up to RM 85 for the entire winter .
The initial ice cover advance near the Parks Highway Bridge char-
acterized the progress ion process through this reach.The ice front
reached RM 82 .5 on November 18 .By late afternoon on November 19
the leadi ng edge was stalled at RM 84.5.The water veloc ity of 3 .5
ft/sec caused all i ncoming ice to be subducted under the leading
edge .Finally the mass of upstream ice and friction against flowing
water upset th is conf iguration and the cover compressed ,
s imultaneeuslv shoving the ice laterally and consolidating t he s l ush
downstream (F igure 6 .25).The compress ion lasted about f ive
minutes.Afterwards the leading edge was located at RM 84 and the
stage at the USGS gage at Sunsh ine had risen 1 foot.The increased
stage reduced the wa ter velocity at t he ice front to 2 .3 ft/sec and ice
f loes were once aga in accumu lating aga inst t he leading edge .T his
sequence was repeated at least four t imes at RM 84 w ith a tota l stage
increase of 6 .5 feet .
On N ov ~m b e r 19 the stage was r ising at entrances to Sunshine S lough
(F igure 6 .26).T he slough and c ide channels were eventua lly over -
topped and flooded .Aga in,n o slush ice ente red th is system due to
an i nsufficient depth at the entrance.These channels subsequently
required an add itional 8-12 weeks to freeze over and many leads were
noted i n th is area a ll winter .
The unusually warm air temperatures at the end of November resu lted
in an unstable ice cover.This instabil ity occurred because the
saturated s lush was not freez ing quickly enough to strengthen the ice
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cover .As described earl ier ,the shearing f orces impa rted by the
fl owing wate r often ca use a complete co llapse of the cover a nd car ry
away much of th e ice .T his cond ition p reve nted the ice cove r from
ad va nc ing beyo nd RM 95 f or ten days .On November 26 the leading
edge was observed at RM 95 .5 but on November 28 th is cover had
co llapsed down to RM 92 .5 and rema ined there u nt i l Decembe r 6 .
Rapid upstream advances of the ice cover genera lly occ ur only with
co ns istently co ld a ir temperatures ,w hich not on ly generate frazil ice
but also stab ilizes the ex ist ing ice cove r.
The s ide channels leading to the entrance of Birch C reek Slough were
flooded but the stage did not increase enough to o vertop the sloug'l
entrance .The maximum i ncrease was 3.1 feet near the entrance to
Birch Creek Sloujjh .An additional foot would have been necessary
for overtopping (Figures 6 .27 and 6 .28).
The tempo rary arrival of the leading edge at RM 95 .5 initiated a
separate 'ice progression up the Talkeetna River.Th is progress ion
on the Ta lkeetna was so lat e,however ,that the majority of the r iver
had a lready frozen over with anchor ice and border ic e,significantly
redu c ing t he vo lume of f raz i l being generated .By mid-December the
ice cover had reached a pos ition about 300 yards upstream of the
ra ilroad bridge and essentially rema ined there for the rest of the
w inte r.
By December 9 t he Sus itna River ice front had advanced upstream
i nto the middle r each above Talkeetna .The ice cover on the lower
river remained unstable and was marked by many extensive open
water areas ,e ither i n ma instem leads or in flooded side channels .
The Chu litna River,like the Talkeetna,had frozen over by lateral ice
growth at the headwaters and was by this t ime gener ating r ~l ittle ice
that no upstream accumulation occurred.The confluence area of the
Chulitna did not freeze over until late March ,1984.Th is was
entirely due to anchor ice and lateral growth of surface ice .
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Trapper Creek was not affected by Sus itna ma instem freeze-up .T he
water level i n the mainstem controls the location of the confluence .
At prefreeze-up stages Tr-apper-Creek d id not merge with the Sus itna
until RM 90.No s lush ice floes drifted up th is creek and fl ow
rema ined unrestricted by ice .With the except ion of some backwa te r ,
Birch Creek and Sunsh ine Creek were also unaffected by the ice
advance (Fig ure 6 .29 and 6.30).The flow in Rab ideux Creek was
low (discharge estimated less than 10 cfs)and the stag ing reached 7
feet over the open water level (Figu re 6.31).This caused the mouth
to flood and the backwater extended a cons iderable distance
upstream .Slush ice floes did enter the backwater area mostly
because the confluence is on the outside of the mainstem bend .The
momentum of the floes traveling down the mainstem propelled the f loes
into Rabideux Creek .When the stage receded the floes were stranded
in the confluence area (Figure 6.32).These ice blocks were strewn
about randomly and did not restrict flow from the creek .
Most of the s ide channels below Talkeetna were flooded to some ex-
tent ,often only saturating the snow cover (F igure 6 .33).Several
side channels ,such as Sunsh ine Slough and Kroto Slough ,remained
f looded all w inter.The max imum stag ing levels seem to be temporary
and water levels along the entire lower r iver receded once the leadi ng
edge had moved upstream several miles.Th is may be due to ice
cover eros ion or seepage of water i nto the underly ing gravels.
Stag ing on ly effects ma instem water levels,creat ing a hydrostat ic
imbalance between surface water and groundwater .The sands and
grave ls of the lower river are extremely permeab le.High surface
waters gradually seep into the sand until an equ il ibrium water level is
reached .Th is is evident by i ncreas i ng water levels i n s ide channel
ponds and decreas ing water levels i n the mainstem for several days
after an ice cover has formed (F igures 6.34).
A reduction in mainstem stage may cause the ice cover to sag and
eventually collapse (Figure 6.35).A th inning of the ice cover by
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erosion has also been measured over high velocity cells along a cross
sect ion .Ice thickness measurements along the banks usually reveal
thicknesses representative of the original ice cover at the time of
progress ion .Th in covers have been located over fast flowing water
e ither at mid-channel or along either bank.This is ind icative of
areas where water velocity (friction)is high enough to mechan ically
or thermally erode the underside of the ice cover .Figure 6.36
illustrates the general freeze-up sequence for the lower Sus itna
River.
6 .2 Breakup
The 1984 lower river breakup was not marked by any unusual or
dramatic events .The processes observed in the spring of 1983 were
essentially repeated.There seems to be no definite starting date for
breakup or,in fact,any well defined i nterval between freeze-up and
breakup.
As previously described,open water leads developed immediately in
some areas where water veloc ities were high enough to erode the
unders ide of the ice (Figure 6 .37).Slush ice thicknesses of 4 to 5
feet were generally required during the i nitial progression to
adequately stabil ize the ice cover .The top surface of this layer
qu ickly froze solid ,being in contact with the air .This layer
gradually th ickened ,as a funct ion of freezing degree-days.Solid ice
th icknesses by the end of January averaged 2 feet.The remaining
slush ice layer under the solid fraction is subjected to mechanical or
thermal eros ion imparted by the contacting flow.The slush ice is
generally loosely packed and when i n contact with veloc ities exceeding
approximately 2 ft/sec simply washes away.The contact surface
between flowing water and solid ice will melts from heat generated by
friction.This appears to be a slower process,however,than the
mechanical eros ion,which has been observed to remove an ice cover
within hours after the initial formation.The following r iver reaches
s6/mm60
seem to be pa rticularly suscept ible to open lead deve locrnerrt ,whe re
an ice cover cannot remain stable for any period of t ime un less co ld
air temperatures override all other i nfluences :
Below RM 9 (t idal i nfluence)
RM 62 to RM 66
RM 70.5 to RM 74
RM 78 to RM 86
RM 93 to RM 95
RM 96.5 to RM 98.5
The reach from RM 96 .5 to RM 98.5 opened with in 24 ho urs after ice
cover progression from November 27 to December 8 ,1983 to a w idth
of about 100 feet at LRX-3 (RM 98 .5).The open water surface area
gradually diminished through the winter but was not observed to
close in 1984 .Reach 5 also opened shortly after the in itial cover
developed in mid-November 1983 .A secondary accumulation pro-
gressed upstream though the lead but never ach ieved a complete
closure .The remain ing reaches eventually froze over by late
January 1984 (Figure 6.38).An ice cover that forms over open
leads,by nature will be less thick that the initial cover .For th is
reason these areas will be the first to open up aga in wit"warmer ~ir
temperatures .Th is is the pattern observed on the lower r iver over
the past three years.By early April 1984 the reaches listed above
were aga in ice free over a port ion of t he cross section.
The f irst i ndications of "breakup "on the lower r iver are the i n-
creased flows from the tributaries .Increased solar rad iation and a ir
temperatures melt the s now and deteriorates the ice .Ice on t he
tributaries is rapidly removed from the lower elevat ions , with open
water at the mouths being t he general cond ition by mid-April 1984.
The major"streams such a s the Talkeetna Riv~r,Montana Creek ,
Willow Creek and Desh ka River erode the Sus itna ma instem ice cover
for a considerable distance downstream from the confluence .The
d istance varies at each tributary and is dependent on tr ibutary f low
volume,velocity and mainstem ice conditions .All the open leads ,
whether at tributary mouths or at high veloc.ity reaches,constantly
enlarged as the ice gradually melted in 1984 .
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Increased flows are not reflected by dramatic increases i n stage on
the lower r iver as t hey are on the middle r iver (Figure 6.46).
Th erefore ,a more gradua l brea kup of the ice cover ta kes p lace on
the lower r iver wit hout t he f ractu r ing and subsequent bu ildup of ice
f ragments i nto j ams,wh ich i s cha ra cte r istic on t he r iver above
Ta lkeetna (R&M 1983 ).A majority of t he ice cover is i n itially
st ra nded on the channel banks.Even when it appears that the ri ver
is open ,as evidenced by the water in long continuous open leads ,
the ice on the ban ks rema ins until water levels i ncrease enoug h to
prov ide bouyancy and carry it downstream.T his occurs f irst from
the upstream port ion of the lower r iver reach .
The 1983 freeze-up init iated w ith flows at the Sunshine gage of about
13 ,000 cfs .The lead ing edge of the ice cover arrived at Talkeetna
w ith the discharge at Sunshine approximately 5,000 cfs.The majority
of the ice cove r in the downstream reaches of the lower r iver,formed
at higher stages , is subsequently no long float ing prior to breakup .
Discharge generally begins to increase in late March from the
Sunsh ine base flow of about 3,000 cfs.The corresponding stage
i ncrease consequent ly breaks up the ice cover ove r the upper reaches
of the lower r iver f irst,s ince th is ice developed at lower freeze-up
f lows .If the ice is st ill s tructu ra lly competent dur ing the d ischarge
i ncrease then large ic e sheets will break f ree from the shorefast ic e.
T hese rema in intact and dr ift downstream until they contact solid ice
or become lodged across the channel.In the latter case a new
bar r ie r is created ,wh ich may cause ice deb r is to accumulate i nto an
ice j am.Th is was observed at RM 79 i n 1984 .Th is ice j am rema ined
on the surface and no sign ificant backwater occurred .The ice floes
causing the blockage weakened ~ter three days and dis lodged.All
the accumulated ice debris rushed downst ream about 1 mile before
contacting a solid ice cover .Here a new ice jam formed,wh ich also
remained on the surface with no substantial increase In stage.
Historically , ice jams have been documented between RM 77 and RM 96
but ra rely do they cause much flooding s ince the broad flood plain
ad jacent to the ice choked channel has a large flow capacity .
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The lower river is usually ice free by May 6 .At th is t ime the middle
river usually has several very large ice jams and the upper r iver ice
may still be intac t.When the upper river ice finally d is integrates
and moves downstream,it takes out the remaining middle r iver jams
and the ice moves unrestricted through the lower r iver .
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TA BLE 6 .1
RE LATIV E STAGE LEVELS O F
S ELECTED TR I BUTAR I ES O N TH E
LOWER S US ITNA R IVER DURI NG F REEZE-UP 1983*
Lead in g Edge
I Loc at ion Alex and er Yen tn a Deshka De lta Willow
Da t e Riv er Mile S lo ugh River Rive r Islands C ree k
10121 0 .0 0 .0 0 .0
I 10127 15.0 1.0
11/1 3 1.5 2 .5 3 .0 0 .0 0.0 0 .0
11/4 42 .0 3 .9
I 11/7 57 .0 2 .5 3 .1
I Total Stag ing 2 .5 3 .0 3 .9 2 .5 3 .1
I
Lead ing Edge
Location Kas hw itna Sheep Goose Montana Rabideux
Date River Mil e Rive r Cree k Creek Creek Creek
I 11/1 3 1.5 0 .0 0 .0 0 .0
11/9 66 .0 0 .0 0 .0
11/1 5 77 .0 3 .1 0 .3 0 .4 2 .5
I 11/1 6 78 .5 7 .0
11 /1 8 8 2 .5 7 .1 1.0
11/21 89 .0 6 .9
11/2 5 9 1.0 1.6
I
To t a l Stag i ng 3 .1 0 .3 0.4 7 .1 6 .9
I
Lead in g Ed ge
I Date Loc a tion Bi rc h S lough C hu l itn a Co nf l uence
11/18 8 2 .5 0 .0 0.0
11/26 95 .5 3 .1
I 1212 2 3 .7
I Tot al Stag ing 3.1 3 .7
I *I nitia l v alues arb itra r ily set a t z ero.
I - 70 -
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s6/mm64
Date
October 26
27
November 1
4
7
9
15
16
17
18
19
21
25
26
December 8
13
22
28
January 5
27
TABLE 6 .2
SUSITNA RIVER ICE COVER
LEADING EDGE LOCATIONS DUR ING
1983 FREEZE-UP
Cook Inlet =River Mile (RM)0 .0
Leading Edge Location
Initia l Ice Bridge at RM 9 .0
RM 15 .0
RM 31.5
RM 42 .0
RM 57.0
RM 66.0
RM 77.0
RM 78.5
RM 79 .5
RM 82.5
RM 84.5
RM 89 .0
RM 91.0
RM 95 .5
RM 98 .5
RM 108
RM 116.2
New Ice Bridge at RM 120.7
Second Leading Edge at RM 127
RM 129 .5
RM 130 .2
New Ice Bridge at RM 135.7
Th ird Lead ing Edge at RM 136 .3
RM 137
- 71 -
--s6/ddl -----------------
TABLE 6 .3
SUSITNA RIVER
1 98~ICE THICKNESSES
0 1s ta nce Fro..Wate r Water Solid Sl ush
lJ!£!ll!!!!~t Bank hI!.1JJ Velocity ----l!1!L --l£L
Riv er Hlle 9 .1
(near Al e xand erl 360 11.~-2 .0 0
5 ~0 17.0 -2.0 0
Oate:January 2 3 7"0 3~.0 -1.6 0
Total Width =8~0 ft .
Average Th i ckne ss =1.9 ft.
To U I
Thi ckness
2 .0
2 .0
1.6
River Hlle 2 5 .9
(Su s ltna Stat lonl 300 \3--2 .0 ~.O 6.0
500 \3--2 .5 3 .5 6 .0
Date:January 2 4 700 13+-2 .3 3 .7 6.0
Tou I Wid th =1000 f t.
Average Th ickness =6.0 ft .
River Hlle 37 .2
(near Oeshka R ive r)2 00 \3--2 .2 0.9 3.1
50 0 \3--2.I 0.9 3 .0
Date :January 2Le 800 \3--2 .5 3 .5 6 .0
Total Width =1000 ft.
Average Thi ckness =~.O ft.
R iver H lle ~6 .5
(West Channel th rough
Del ta I sland s)200 \3--1.7 0 1.7-
300 11.0 -2.5 2.5 5.0
Oate :Janua ry 2 ~~OO 10 .0 -2 .5 3.5 6 .0
Total Width =600 ft .
Ave rage Thickness =5.5 ft.
--
River Hll e ~5 .1
(East Channel through
Del U Islandsl 100 10 -2 .5 0 2 . 5
200 10 -2.3 0 2.3
08 to :JanU8 ry Zit
Total Width =30U ft .
Average Th ickness =2 .~ft.
•Ihese value s were not I nc l uded I n the ave rage Ice thickness .Site evaluat ions were u sed to deter.lne
th e probabl e re p re sert t e t Ive Ice thickness at t he t l. a of Ice cover progression.
s6/dd2
TABLE 6.3
(cont'l
SUSITNA RIVER
1964 ICE THICKNESSES (Cant .)
b.!!£!!..I..lon
R iver loI i I e 6 1. 2
(naa r t<a sh...,i t.n a R i ve r )
Oate :J anua ry 2 4
Total Wid th =100 ft .
Av erage Thi ckne ss =7 .3 ft.
D i s ta nce from
_l&ll...l!!.n!!.
20 0
400
600
Water
!lID!.lh
13+
10.0
10 .0
Water Sol id Slush
Veloc ity ~--lll...
2 .9 5.I
2.7 5.3
3.0 4.0
To ta I
Th icknes s
7.0
8.0
7 .0
River Hi I e 68.5
(nea r Sheep Cr ee kI 7 00 13+-2 .8 5.2 6.0
..0 0 13+-2 .0 3 .0 5.0
Dat e : Ja nua ry 2 4 6 00 7 .0 -1.7 5.3 7.0
Total Width =60 0 ft .
Average Th ickn ess =6 .7 ft .
River Hi I e 17.U
(a t HonLana Cre ek I 20 0 7.0 -2 .0 5 .0 7 .0
400 6 .0 -2 .3 3.7 6 .0
Da ta:J alillit t'Y 2 1.4 6 00 13+-1.3 0 I.3*
TOL al Wid tl.=lO U f t .
Average Th icknes s =6.5 ft .
Ri ve r H i 10 92 .6
(nea r Birch S lough I 20 0 13 +-2 .3 0 2 .3
400 10.0 2.5 ft/.1.6 0 1.6
Oa t e :Ja nua r y 2 4 60 0 4 .4 -2 .3 0 2.3
l ot al Wid LII ="IOU f t .
Ave rage Thickness =2 . 1 ft .
Riv or Hi I e 9 6 .f>
(Chu I i t n a Co nf I u euc e )OPEN LEAD
86 6.2 4.4 ft/s 1.5 4.7 6 .0
Oa tti :J amlii f'Y 2 6
I llt al Widtl.=3UU f t.
Ave rag e Th i cknos s =6 .0 n .
•-it"lose-vilyuus-worti no t i nc I ud ud l "ilthe a ve rage --i ce th ickness .S ite evaluat io ns we re us ed to determ ine
the p rob abl e re p re se uua t I ve i cu th i ckness a t t he t ime o f i c e cover progres s ion .
--s 6/dd3 -----------------
TABLE 6 .3
(cont 'l
SU SI TNA R I VER
1984 ICE THICKNE SSES (Can t.)
D is tance From Wat e r Wa t er So li d Slush To ta I
Loca t i on Lef t Bank Dep t h Velo c ity --!£!L .i!1lL Thlc knes.§
R i ve r Hile 10 3 .3
(LR X-9 1
31 3 9 .0 -2 .0 7 .0 9.0
4 39 12 .0 1 .9 rc / «1.5 5.0 6 .5
Date :January 2 6 5 58 10.6 -2.0 7.0 9 .0
To tal Width =6 00 ft .
Av era ge Th i cknes s 8.2 ft.
Riv er Hi Ie 113.0
(LRX-18)2 38 6.6 1. 6 ft l s 2.0 0 2.0*
341 7 .6 -2.5 5 .1 7 .6
Date :Janua r y 2 6 4 67 6.0 -2.3 3 .5 5.8
To ta l Width =500 f t .
Ave rage Th i ckness =6.9 ft .
Ri ve r Hl le 120 .6
(LR X-24I 2 78 12 .2 -2.8 9 .4 1<:•.I
37 3 11.7 -2 .0 6 .6 8.6
Dat e:Ja nua ry 26 '141 8 .0 2.3ft/s 1.5 0 1.5*
Iota I Wi d t h =500 f t .
Ave rag e Thi ckness =10 .4 ft.
R ive r Hll e 123.4
(LRX-27I 284 11.5 -1.8 B.9 10.7
368 12 .2 -1.8 8 .7 10 .5
Date :Janua ry 26 461 5 .0 4 f t l s 2 .4 0 2.4*
To UI Width =50n ft .
Ave rage Thick ness =10 .6 f t.
River Hi I e 126 .2
(LRX-2 9I 2 52 4 .5 -2 .3 1.7 4 .0
381 6 .5 -1.8 4 .7 6 .5
Date :J an ua ry 26 5 13 8 .0 4 .5 ft l s 1.8 0 1.8*
Tota l Widtl.=5 75 f t .
Average Thickne ss =5 .3 ft •
•---l hese val ues we re not In c luded in t he average ice t h i ckness . S ite evaluat ions were used to dete ra lne
the p r ob nb t e r e pre se nt at ive ice t h ick ness at t he t lmo o f Ice cover progress ion .
s6/dd4
TABLE 6 .3
(cont',
SUSITNA RIVER
1964 ICE THICKNESSES (Cont .)
Oi s tance froll Water Water Solid Slush Tou I
b!!l1ll!mJ I eft Bank IWU.ll ye loc I tl(---l.!<L J.£lL Th i cknes s
River Hi Ie 126.5
(near lRX-311 369 4.6 -1.6 0 1.6*
469 6 .6 -1.6 3 .6 5 .2
Date :January 21 569 7 .0 4 .5 ftls 1.0 0 1.0*
lotal Width =6 00 ft .
Average Thi cklles s =5 .2 rt .
River Hi Ie 136 .6
(LRX-45 1 96 6 .0 5 ft /.1.1 0 1.1
166 9 .5 -0.9 3 .1 4 .0
Oa te :Janua r y 27 267 1 .1 -1.0 0.5 1.5
lotal Width =350 ft.
Averag e Thi ckness =2.2 ft.
*Ihese v a lues were not includ"d in the ave rag"ice thickne ...Site evaluation.were u.ed to detenolne
th"probable repre.entative Ie"thlckne.s at the time of I ce cover progression.
s6/mm65
through
to more
la ck of
S US ITN~J OINT V ENTURE
-76 -
..•
~"".'
F IGURE 6.2
October 17 ,1983 .Bord er ic e beg in s to deve lop on th e middl e r iver .
F IG JRE 6.1
October 18 ,1983 .Th e ice ge ne ra ted in th e u pper r iver can yon flo ats
th e middl e r ive r r ea ch wh ere much o f it melts .Thi s area i s e xposed
s olar r adi ati on b eca u se of th e n ort h /sout h riv er o r ientat ion and
to po gra phi c s had i ng .
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FI GURE 6 .3
October 21,1983 .When the water lev el in t he s eco nd ary ch ann els recedes,
then slush ic e becomes groun ded o n th e bottom an d t he chann el q uickly fill s
w ith ic e.
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-77 -
SUS/TNA J O/NT VENTURE
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R&M CONSUL.TANTS.INC......01""....O .O~O I.T .~"NH ....u.v....a ••
R IVER AT RIVER MILE Ii OCTOBER
FIGURE II."
78
SUSITNA J OINT VENTURE
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s6/mm68
"'-_.."...:5 '~.-......._---..........
~~:-='~~-~.~._,':~:'~i::i~
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FIGURE 6 .5
Octob er 25 , 19 83 .When hi gh volu mes of ice are generated and lower r iv er a ir
tempera t u res rema in b elow Do C,slu sh r each e s the r iver mouth where wa ter
ve locit ies a re s ign ifica nt ly c ontroll ed b y Cook I nlet t idal fluct uat ions .
..-------._----,
FIGURE 6.6
October 28 ,1983 .High tides o c curred duri ng t his tim e i n Octo ber .Th e s lush
ice v elocity slowed to th e po i nt th at fr ict ion along t he b an k and w ith in the ice
pack exce eded t he fri ctio n imp arted b y th e s low mov ing wa ter ,a nd t he f low ing
slus h s t opp ed mov in g .Look ing ups tream at riv er mile 9 ic e brid ge .
..79 ..
S US I TN ~JOINT VENTURE
I s6 /mm69
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SUSITN ~JOIfJT VENTURE
S lOpS ,
_....,
1
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- 80 -
FI GUR E 6 .7
When the flow in g s l us h ice cover s lows and f ina lly
accumulates along th e u p stream "edge" of the cover.
October 27,1983 .
'incomi ng slu sh rafts
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s6 /mm 71
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F IGURE 6.9
Nov ember 1 ,1983 .Th e ice co ver lengthens or pro gresses upst r eam as s l ush
accumu lates a long t he "lead ing edg e ". Wat er lev e l ri ses d ue to disp lacement b y
ice and r es ista n ce t o fl ow .
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~,
Ii -•
............_...
FI GURE 6 .10
Nov ember 1,1983.T he lead i ng edge at RM 3 1 .
i ndic a t e d b y t he f loo ded sn ow a nd d a rk p at ch es ad j acent
~,.';1
I
Note t he inc re ased
to t he ma i nst em .
stag e
I
I - 82 -
SUSITN I'J OINT VENTURE
-------------------
SUSITNA RIVER ICE LEADIN G E DGE PROGRESSION RA TES (mlles /deyl RELATIV E
TO THE THALWEG PRO FILE F ROM RIVER MILE 0 (Coo k Inletl TO RIVER MILE 155 (DEVIL C ANYO N)
160140
\OOLD CAUK
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'<,BL OUGH '
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AA.B'-AU.CAEEK ~../
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"OOOeE C RU K aL OUGH
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FIGURE 6 . 12
84 SUSITNA J OINT V ENTURE
s6 /mm74
slush ice r af ts
SUS/TN '&'J OIfJT V ENTURE
-8 5 -
F IG URF.:6 .14
s hows a fl o oded s ide ch an n el a nd t he
F lood ed snow is vi si ble as a d ar k b a nd .
-.:.-..:....'~--"--.-.-----:-::-...~
F
Nov emb er 1 ,198 3 .T his
r es tr icted t o t h e ma i nstem .
F IGURE 6.13
Nov e mb e r 1 ,1983 . Mo s t of th e lower riv er s ide cha n ne ls ,s uc h as A lexande r
Slou gh ,a re flooded wh en th e ma in c han ne l stages but few are deep e nou g h t o
allow passage o f sl ush raft s , wh ich ge ne ra lly require two to three feet of w at er
dept h .
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s6 /mm75
FIGURE 6.15
Nov em ber 1 ,1983 .Mou t h o f Will ow Creek .Mains et»
c aus ed a bac kwater a rea at t he conflu ence .Stage
ov e rtop p ed the a lluvial f an b ut fl ow was not r erouted .
ice co ver
in c reased
prog ress ion
and water
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-86 -
SUS /TN ,"-JOIfJT VENTURE
---_.'"-<._-
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F IGURE 6.16
O ctober 4 ,1983 . Mout h o f Ka shwit na R iver before f reez e-up . F low i s from le ft
to r ight .The Sus itna ma ins tem is in the foreground.
FIGURE 6 .17
Novembe r 1,198 3 .Mou th of Kas hwit na R iver just pr ior t o S us i tna f r eeze -up .
Lateral a cce ss c han nels hav e dewatered.Mai nstem f reeze -u p h as littl e effect on
Kas hw it na flo w .T his tr ibutary fr eezes ov er p r imarily b y lateral bord er ice
g row t h .
I - 87 -
S US /TNt.J O INT VENTURE
F IGURE 6 .18
October 4 ,1983 .Mouth of Sheep Cre ek.Thi s c reek ente rs a s ide ch ann el ,
whi ch r ema ins flooded all winter but littl e slush ic e e n ters f rom the ma in stem.
S USITN ,t.J OIN T V EN TURE
-88 -
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FIGURE 6.19
Novembe r 1 ,1983 .Mout h o f S h eep C reek.Ma in stem f reeze-up does not
s ig nif icantly effect th is area .Water le vel o n staff gage ro se about 0 .5 fe et .
An ic e c o ver ha s started to fo rm at th e mou th b y accumulating slush f rom
Sheep Creek .
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F IGURE 6 .20
Octob er 2 1,1983.Mouth of Goo se Creek .A s ide ch ann el f rom th e ma in stem
co mes in on th e left.Thi s s ide ch an nel e ve ntua lly dewaters and d id no t
o ve rtop du r ing f reez e-up in 1983 .Goose Cree k prov ided most of the fl ow i n
th e c h ann el.
F IGURE 6.21
November 1,'1983 .Mou th of Goos e Cre ek .Lookin g downstream a t the con flu -
ence w ith the dewatered side channel .Wat er level at th e staff g age rose
0 .45 fe et during main stem f ree ze -u p .
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SUSfTN,t.JOINT V ENTURE
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F IGURE 11 .22
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Octob er 4,1983 .Mo ut h
tr ibutary fl ows d i rect ly
stag i ng d uring f reez e-up .
FIGURE 6 .23
of Montan a Cree k.
into th e ma instem
F low
and
is f rom le ft to
is s ign if icant ly
r ig ht .Th is
e ffected b y
I ~...---..-.
--'
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FIGURE 6 .24
Dec embe r 28 ,198 3 .Mout h o f Montana Cree k .T he water lev el h a s rise n
feet an d flood ed the al luvial fan .Bac kw ater e xtended u p Mon ta na
b eyond th e Park s Hig hway bridge .S ome f low was r e routed t hroug h a
cha nnel a long the left b a nk.
s e ven
Creek
small
I - 91 -
SUSITN ,t.JO INT VE NTURE
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FIGURE 6 .25
Nov e mb er 24.1983 .Park s High w ay br idge at S u ns hine .Th e i nc rease i n w ater
le vel c aused the bord er ic e t o f ragme nt a nd be sh ov ed onto the left ban k .Th e
ic e cov e r h as e r oded aw ay to f orm an open lead between the second a nd t hi rd
p il ing .
FI GURE 6 .26
Octobe r 21 ,1983 .Entrance to S u ns h i ne s ide c hannel .
prio r t o f reeze -up .Th e ic e c o ve r c a us es o vertop p ing
rema ins f looded f o r t he durat ion of t he w i nter .
td?d /..;",
Th is a re a dewaters
and t h e s ide ch an nel
SU S/TN t.JOINT VE NTUR E
-9 2 -~/l
R &~M~":C~O;;;=::N=;:;S::'U~LT:::":A:='N==::T=S:=.=:''=I\:=='·=C:=.=....ca ........a ea L-CD .a T".I...""....A..I,J .V."'O••
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is I II the
i s flo o l ed
c ha n ne l
S ide c han nel
--
FI GURE 6 .28
Head entrance to B i rch Slough .
ice b ut n o wate r ente red th e s lo ug h .
............
~-..-
.\
"';....
s 6/mm82
Nov e mber ·26 ,1983 .
and pac ked w ith s lush
F IGURE 6.27
Sep tember 17 ,1983 .Head o f Bi r ch S loug h .S us itna s ide
f or egrou nd .a nd s lo ug h is dewatered .Flow is fro m left to r ig ht.
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I -93 -
SUSITN~J O/fJT V ENTURE
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FI GURE 6 .30
Novembe r 21 ,1983.Mou th of B i r ch C reek .Lead ing edg e is a dja cent to the
co nfl uence o n the ma in stem .Sta ge has i nc r ea se d and flo oded t he c r ee k mouth
but n o slush ice entered th e b ackwat e r a r ea .
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FIGURE 6 .29
S ep tember 17 ,1983 .Mou t h o f B irc h Cree k .
f oregro und ,fl ow is from left to rig ht .
....----.
Sus itna ma instem
r ;»
•
i s i n the
I ~~f\::;"~ClII===========
r=I&M CONSULTANTS,11\:::.
.....0 .........nc.O\.OOI5T "P I..A N .....,..!>U AV It"O Oll lo
-94 -
SUSITN ","J OINT VENTU RE
s 6 /mm84
F IGURE 6.3 1
October 21,1983 .Mou th o f Rab id e ux C ree k .T hi s a rea i s i nfl u e nc e d a ll y e a r
b y bac kw ater from hi gh ma i nstem stag es .F low is fro m r igh t t o left .Flow f rom
Rab id eu x C ree k w as n ot r ero u ted dur in g f re ez e-u p.
.•-.
1-
---
SUSITN;:'J OINT VENTURE
-95 -
~'L-
l=l&M CONS ULTA N TS ,I N C .
....a ........o co...oo .• ,..•....N .....A.5 U .V l''''C ••
FI GURE 6 .32
Nov emb er 23 ,1983 .Mout h o f Rab ideux C reek .Stagin g c aused water lev e ls ',0
i nc r e a s e o ver 6 .5 feet .The r esulti ng bac k wat e r wa s deep en ough to a llow
s lush ra ft s t o dr ift into the confluence area .The wat e r e v ent ual ly r eceded an d
le ft the ice f loes s tranded .
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FI GURE 6 .33
Nov emb er 2 7, 1983 .Nea r th e Ta l keet n a Ri v er c onfl uence .Le ad i ng e d ge h as
started adv a nci ng ag ain a fter a ct ua lly reced ing d ur ing th e p re vious s e ven d ay s.
No te floo ded s now an d ex tent of f looded ar ea.
I -96 -
S US I TN ~J OIN T V ENTURE
OPEN L EAD
D~EMBER
SUS/TNA JOINT VENTURE
OPEN LEAD
._- -
\
\
\
\
\
\
\-----
NOVEMBER
MONTH
FIGURE 11.34
9 7
~---------------
""'-------------
OCTOBER
-----._--------..-.-
5
4
3
2
·4
R&M CONSULTANTS,INC.
.Nlal....•••aaOl-oalaTa _I.. N"",. . .a u_v.yo••
RELATIVE STAGE LEVELS AT SELECTED SITES DURING 1983
SUSITNA RIVER FREEZE UP
LEGEND
----INTERPRETAT ION BASED ON OBSERVAT ION
--INTERPRETED STAGE BETWEEN DATA POINTS
•SURVE YED DATA POINTS
ALEXA NDER
SLOUG H
(RM 14 )
5
DELTA ISLANDS 4
S IDE CHANNE L 3
ENTRANCE 2 }
(RM 48)+...__L _
-------J \---\-------------
5
DESHKA RIVER /4
KROTO SLC'UGH 3
(RM 40.1 )2
1
5
CHUL ITNA
CONFL
(RM 98 .5 )
MONTANA
CREE K
(RM 76.9 )
KASHW ITNA
R IVER
(RM 60)
=================..=======
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IIIr;
III
f
/)
~C...
IIIr
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---"'--~~.~:.;'..::.:..
,;.:,\.~....>,---
.,--_.--~-
__-..'I
"_I '".:....-::'.'::..-:'..
--------::-,~-:;:,
.c--_.
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F IGURE 6 .35
December 28 .1983 .Nea r LR X-9 .Th is ice cov er is dete riorat i ng a s e vide n ced
b y t he sagg ing co ver over the f low ing wate r .A lead will e ve nt ua l ly o pen up i n
the s agged port ion of the sect ion.
I ::;~~'==!.~~/:,;,1='='=='======'============
R&M CO N S ULT A NTS,I N C •....D........OI;O..OD,. ,...•...A .........~..u....II '"0 ...
-98 -
SU S/TN,<-J O IN T V ENTURE
---------------LOWER RIVER TYPICAL CROSS SECTION ----
BANK SIDE CHANNEL MAIN CHANN EL I SLAND
SIDE
CHANNEL
SLUSH ICE COVER
OPEN LEAD
••I:IIIM~!I:;:·
SNOW CDV ER -
FRACTURED BORD ER IC E
FLOODED SNOW
WATER SURFAC E
...
"e:am..
i.>co
.n'0£2~m:c:
1~B:i
12I~.mc-"-!2~nI •
~i~
~»
is •
~~;:~
C!:tI~
"'§
<D
<D
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s6/mm89
F -.
.-...:...
"#:.,..-,'.
-~~,'.
,..•~:...
•':~1
"';:.\t~:
~\IX\.'"'"
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De cemb er
i nc reased
up.
28 19 83.
a bout s ix
FI GURE 6 .37
O pen lead downstr eam of Suns hin e near RM 8 0 .Sta ge
feet during progress ion and receded whe n th is lead opened
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FI GURE 6.38
December 28 ,1983 .Secon da ry leadi ng edge p rog res sin g up st ream throug h a n
o pen lea d.T he p ro gres sion rate is s low a nd the e nt i re length of thi s op en lead
di d not free ze o v er .
I R & M C O N S U LT A N T S ,INC••NGI........O.O~DO I .T._\.AN""...•.....v ...a ••
-100 -
SUS/TNA J O/NT VENTURE
7 .0 MIDDLE R IVER ICE STUDY
- 101 -
s6 /mm90
Da ily observat ion were made at t he Go ld Cree k bridge mon itor i ng the
follow ing pa ramete rs:
RM #
98 .2
98.4
98 .6
103 .3
106 .2
113 .0
120 .5
123 .3
126.1
128 .7
130.9
134 .2
136.5
2.2
2 .3
3
9
near 10.3
18
24
27
29
near 31
near 35
40
45
Cross Section #
Minimum and ma ximum da ily a ir tempera tures
Water temperature (mercury hand held thermometer)
Water level (wire we ight read ing )
Shore ice width and th ickness
Water velocity (surface max imum)
Depth of snow
Ice concentrat ion (percent of water surface covered)
Water leve ls we re measu red du r ing t he open water hydrograp h recess ion
and dur ing the f reez e-up of the midd le r iver reach (Table 1).Cont inuous
s tage rea .:J ings were recorded w ith a Datapod at LRX-3 (Ta ble 2)and da ily
measurements were obta ined w ith a w ire we ight at LRX-45 n ear Go ld C ree k
(Table 3 ).The rema in ing locations were measured per iod ica lly w ith a level
and su rvey rod .
As i ndi cated earlier in th is report ,the scope of work for f isca l y ear 1983
ice study emp has ized documenta tion 0 ;lower r iver ice processes .Quant i-
f ication of middle ri v er ice processes was also requ ired for ongoing
computer s imulat ions of w ith -project ice cover development .Water surface
elevat ions we re surveyed at the follow ing cross section :
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Porosity of the frazil slush was period ically measured throughout freeze-up
(Table 4).This parameter was required for computations of ice d ischarge
(Table 5).Frazil samples were collected at Watana,Gold Creek.and
LRX-3 at the Chulitna confluence .The procedure was as follows :
1 .A wire mesh (one-quarter inch)container with dimensions of "I
cubic foot was carried out to a water depth of about 2 feet .
Usually a slush ice raft was intercepted wh ich quickly f illed the
container.
2.The water was allowed to drain from the slush .A ma jority of
the water dra ined out immed iately but several minutes were
requi red until only drops issued from the conta iner .
3 .An Ohaus 100-pound capacity portable sca le was used at the s ite
to we igh the conta iner and then the conta iner w ith ice .
4.The weight of fraz il divided by the density of solid ice is the
percent of ice i n the conta iner,the rema in ing fract ion is t he
vo id space or a i r .
The results of these measurements were remarkably cons istent however.
they do not generally agree w ith published values for fraz il ice poros ity .
Average poros ity of Sus itna River ice was 0 .32,compared to the accepted
value range of 0.4 to 0 .6 .The low porosity of the samples taken on the
Susitna may be related to the age of the fraz il .I n fact.the ice samples
collected were composed of course (app roximate d iameter 3 /8 to 1/4 inc h).
compacted granules of ice wh ich hardly resemble frazi l (F igure 7 .1 ).The
ice gra ins were compacted so that each grain contacted another and only
the interstices conta ined water .Fu r t her compaction did not seem poss ible
w ithout deform ing t he gra ins .The accepted v alues for poros ity of f razil
are probably based on newly formed Ice crystals and not t he
me tamorphosed granules experienced on the Susitna .These observat ions
are s ign ificant when comput ing ice d ischarge .The ice v olume i s a
- 102 -
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n ecess ary parameter f or determ in i ng ice cover progress ion r a tes .Ice
d isc harge or the vo lume of ice i s computed based on s u rface v elocit y,
channel w idth,slush th ickness,surface ice co ncentrat ion and poros ity.
Prel iminary computations resulted in extr eme values of ice volumes ,
however,th is i s probably due to the use of a surface velocity wh ich was a
measured max imum and not an average cross sect ional velocity .The va lues
for ice vo lume s hown on Table 5 should be used for r ela tiv e da ily
compar ison on ly,and may no t represent the act ua l ice d ischa rge at Go ld
Creek .Furt her stud ies and data acq uis itio n w ill h elp to ref ine these
co mputations for more represen tat ive va lues.
Water temp-er-atur-es WE're mon itored a t Denal i,Jay Cree k and Watana during
September and October 1983 in order to track the cooling process down to
O°C .See Table 6 .
On December 9,19 83,t he leadi ng edge of the progress ing ice cover en-
t ered the midd le rrver reach a t RM 98 .6 .The freeze-up processes were
docume n ted once per w eek u nt il t he le adi ng edge reac hed Gold Cree k.
Water surface e le vat ions were surveyed above and be low the leadi ng edge,
h owev er ,the exact ice f ront became d iff icu lt t o def ine by mid -December .
On Decem be r 22 ,a second leading edg e was observed at RM 124 ,j ust
upstream of Curry .The r ive r downstream between RM .120 and RM 118
was st ill open and the lead ing edge was stalled.Hea vy anchor ice
depos its were observed w ith in the open lead .Th is ancho r ice had
not iceab ly ra ised th e wa ter le vel and flo oded the sur ro und ing shore ic e
and s now .Th e seco nd leadi ng edge apparent ly was i n iti ated b y a c ha nnel
cl o su re at RM 120.7 .S ince t he cl osure was not w itnessed t he p rocesses
lead in g u p t o th is e ve nt can on ly be i nterp r eted from th e e x ist ing ic e
s t ructu re .
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Th e s ide channel be low Curry wh ich
a la rge v olume of th e Ice f lowi ng
Apperrd !x B .The sharp r iver bend
r uns from RM 119 .2 to 120 .5 con veys
d own the Sus itna ,see sheet 11 ,
at RM 121 fo rces the water and ice
I - 103 -
•
s6/mm93
against the west bank adjacent to cross section 24.The momentum of the
flowing ice keeps the floes against this right bank and subsequently
carries most of the slush i nto the side channel.The proximity of the
leading edge near ,t he side channel mouth had ra ised the water surface
elevation and reduced the water velocity.The side channel therefore
quickly became ice choked and no longer capable of conveying all the slush
ice.The ice backed up in the s ide channel and was prevented f rom
diverting into the ma instem by the velocity d istribution and a gravel bar
located at RM 120 .3.A new leading edge was subsequently started and
moved past Curry (LRX-24)probably on December 21 ,1983 .
The open water be low Curry on the ma instem eventually froze over by
border ice growth .Two anchor ice dams were observed in the lead,at
RM 120 and RM 119 .6.Th is created some backwater pond ing which facil-
itated faster lateral growth of border ice (F igu re 7 .2).
By January 5 ,1983 the second lead ing edge was located at Sherman near
RM 130 and since very little slush ice was flowing i n the open water ,the
ice cover progress ion was relatively slow (F igure 7 .3).By this t ime the
river above Devil Canyon had essentially frozen over and stopped generat -
i ng substant ial volumes of frazi l.The remain ing open water through Devil
Canyon and on down to the lead ing edge appeared to produce relati vely
low volumes of slush.The frazil generated,however ,was "active"
meaning it would adhere to 'any object that the crystals contacted.The
anchor ice dams mentioned previously,had also developed at RM 130.5,
132.5,134,134 .'3 and 135 .5 .The anchor ice accumulated on the bottom
rocks to depths of 1 to 2 f eet .This subsequently raises the water level
and causes a backwater zone .Water levels may r ise enough to fractu re
border ice .F igure 7 .4 shows the results of th is process at RM 135 .6 i n
1983.A third leading edge began but progressed o nly about 1 mile before
becoming an indefinite zone of accumulat ion.The open water area between
RM 130 and RM 135 .6 eventually closed by border ice extens ion .
- 104 -
•
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•
•
•
•
•
•
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Figure 7.5 shows a schematic of the freeze-up sequence at a typical middle
river cross section .Day 1 shows open water with slush rafts floating
downstream,border ice with some slush deposited underneath .On day 2
the leading edge has progressed past the cross section.Stagil ..3 has
broken up the border ice which is now incorporated in the slush cover .
The ice cover has not solidified and is uniformly thick across the section.
Lateral shoving has pushed the ice f rom bank to bank .On day 20 the
illustration shows the ice cover has sagged due to reducing water level
and has also thinned over the high velocity sect ion of the channel.This
depiction misrepresents solid ice cover thickness however.Typically the
slush ice freezes from t he su rface down in a relatively even layer and
rarely has it been observed to freeze solid as shown .The true th ickness
of the solid layer depends on the number of freezing degree-days .Dur ing
a cold winter ,obv iously the solid fraction would be thicker than dur ing a
warmer winter .
Day 40 shows the th in portion of the ice cover finally eroded away to
expose open water.This occurs generally over high water velocity zones
where friction erodes the underside of the cover .
- 105 -
I s2lbb1
I
I TA BLE 7.1
SUSITNA R IVER Between th e
CH ULI T NA CO NFLUENCE (RM 98 .5)and
I GOLD CREEK (RM 136 .5)
Water Surface Elevat ion s i n Feet (MSL)
I
Date of Survey
I Locatio n 10/6 10/17 10/21 11 /4 11,'1 8--
L RX-45 Gol d Cree k RM 136 .5 683 .59 683 .35 683 .06 681.84 681 .24
I L RX-40 RM 134 .2 657 .21 654 .24
I Near
LR X-35 RM 130 .9 61 4 .92
I Near
LR X-31 RM 128 .7 59:..86
L RX-29 RM 126 .1 569 .44 56 j .55
I LR X-27 RM 123.3 541.11
I L RX-24 RM 120 .5 520 .93 520 .05
L RX-18 RM 113 .0 460 .18 457 .74
I Near
*L RX -1 0 .3 RM 106 .2 2 .25
I LR X-9 RM 103 .3 377 ..52 37 5 .67
I LR X-3 RM 98 .6 342 .55 341.51 34 1 .30 339 .65 339.40
L RX-2 .3 RM 98 .4 341 .24 339 .23
I LRX-2 .2 RM 98 .2 340 .86 33 9 .3 6
I
I Locat ion of Lea d i ng Edge No Co ver No Co ver No Co ver RM 42 .0 RM 82 .5
D ischarge (U SGS Gold Creek )8800 7800 6900 3900 2800
I *Surv ey ed f rom A rbit rary Reference Datum of 10 f eet .
I -106 -
s2lbb2
TABLE 7 .1 (cont.)
SUSITNA RIVER Between the
CHULITNA CONFLUENCE (RM 98 .5)and
GOLD CREEK (RM 136.5)
Water Surface Elevations i n Feet (MSL)
Date of Survey
Locat ion 12/13 12/22 12/28 1/5 1/27
LRX-45 RM 136.5 681.59 681 .96 682.73 683 .49 684 .64
Gold Creek
LRX-40 RM 134 .2 653 .86 654 .55 655 .23 657.58
Near
LRX-35 RM 130 .9 617.55 617 .05 618 .16
Near
LRX-31 RM 128 .7 593 .95 596 .54 595 .58 594 .99
LRX -29 RM 126.1 563 .49 573 .53 572 .59 571 .53 571 .08
LRX-27 RM 123.3 545.31 544.35 544 .43
LRX-24 RM 120 .5 520 .82 522 .26 523 .58 523 .89
LRX-18 RM 113. 0 461 .87 461.36 461 .13
Near
*LRX -l0 .3 RM 106.2 7.65
LRX-9 RM 103.3 383.57 381.32 381.41
LRX -3 RM 98 .6 342 .80 343 .07 343.00 341.34
LR X-2 .3 RM 98 .4
LRX-2 .2 RM 98 .2
Location of Leading Edge RM 108 RM 116.2 RM 129.5 RM 130.2 RM 130 .2
RM 127 .0 RM 136 .3 RM 136 .8
Discharge (USGS Gold Creek)3400 BACKWATER
*Surveyed from Arbitrary Reference Datum o f 10 feet .
- 107 -
- 108 -
s2 /bbJ
A max imum stage of 344 .63 feet was reached at 1530 on December 9 , 1983
co inc ident with the lead ing edge of ice cover pass ing this cross sect ion .
TABLE 7 .2
CHULITNA CONFLUENCE STAGE DATA
Recorded at LRX-3 ,Left Bank
33 9.50
339 .40
33 9.37
339 .50
339 .50
339.50
339.37
339 .17
341.47
342 .67
342 .83
342 .83 .
342.80
343 .03
342 .53
342 .37
342.43
342 .53
342 .67
342.63
343.00
December
1983
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Water Su rface Elevat ion
Date Feet (MSL)
333 .57
339 .50
339 .57
339.40
339 .57
339.53
339 .37
339 .43
339 .37
339 .53
340.10
339.87
340 .03
339.37
339 .50
339.57
339 .50
339 .53
339 .47
Water Surface Elevation
Feet (MSL)Date
November
1983
1
2
3
4
5
o
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
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I T ABLE 7.3
GOLD CREEK WI RE WE IGHT READ INGS (FEET )
I with cor respo nd ing values in USGS
Datum (f eet).Mean Sea Leve l (f e et)and Discharge (d /sec)
I
Date WW USGS MSL Q
I October ,1983
1 GO .10 8 .47 684.79 13600
I 2 59 .95 8 .32 684.64 12800
3 59 .65 8 .02 684.34 11600
4 59 .38 7 .75 684.07 10800
5 59 .10 7.47 683.79 9600
I 6 58 .90 7 .27 683.59 8800
7
8 57.90 6 .27 682.59 5750
I 9 58 .30 6 .67 682.99 6900
10 58.85 7 .22 683.54 8400
11 59 .05 7 .42 683 .74 9200
I .12 59 .45 7 .82 684 .14 10800
13 59 .75 8.12 684 .44 12000
14 59 .55 7.92 684.24 11200
15 59 .15 7.52 683.84 9600
I 16 58 .82 7.19 683 .51 8400
17 58 .61 6.98 683 .30 7800
18 58.48 6 .85 683.17 7500
I 19 58 .64 7 .01 683.33 7800
20 58 .44 6.81 683 .13 7200
21 58.37 6 .74 683.06 6900
I 22 58 .25 6 .62 682.94 6600
23 58.17 6 .54 682.86 6300
24 57 .97 6 .34 682 .66 5750
25 57.GO 5 .97 682.29 5000
I 26 57 .63 6 .00 682.32 5000
27 57 .64 6 .01 682.33 5000
28 57 .55 5 .92 682.24 4750
I 29 57 .61 5.98 682.30 5000
30 57.73 6.10 682.42 5250
31 57 .84 6.21 682.53 5500
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s 2/bb5
TA BLE 7 .3 (cont .)
GOLD CREEK WI RE WE IGHT RE AD INGS (FEET)
with co r responding va lues in USGS
Datum (feet ),Mean Sea Level (feet )and Discharge (d/sec )
•
Date WW USGS MSL Q
November ,1983
1 57 .63 6 .00 682 .32 5000
2 57 .58 5.95 682 .27 5000
3 57.40 5 .77 682 .09 4500
4 57 .15 5 .52 681 .84 3900
5 57.20 5 .57 681 .89 4000
6 57.05 5 .42 681 .74 3 700
7 56 .80 5 .17 681 .49 3300
8 56.70 5 .07 681.39 3100
9 56 .83 5 .20 681 .52 3300
10 56 .70 5 .0 7 681.39 3100
11 56.75 5.12 681.44 3100
12 56 .70 5 .07 681 .39 3 100
13 56 .65 5 .02 681 .34 3000
14 56 .65 5 .02 681 .34 3000
15 56 .77 5 .14 681.46 3 100
16 56 .60 4 .9 7 681.29 3000
17 56 .67 4 .9 4 681 .26 2800
18 56 .57 4 .94 681 .26 2800
19
20
21
22 56 .85 5.22 681 .54 3300
23 56 .94 5 .31 681 .63 3400
24 56 .75 5 .12 681 .44 .3100
25 56 .79 5 .19 681.51 3300
26 56 .85 5 .22 681 .54 3300
27 57.so 5 .87 682 .19 4800
28 56 .95 5 .32 681 .64 3400
29 56 .9 4 5 .31 681 .63 3400
30 56 .95 5.32 681 .64 3400
-110 -
s2/bb7
TABLE 7 .3 (cent ')
GOLD CREEK WIRE WEIGHT READINGS (FEET)
w ith correspond ing values in USGS
Da tum (feet),Mean Sea Level (feet)and Discharge (cf/sec)
Date
January ,1984
ww USGS MSL Q
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
58.52 6 .89 683.41 *58.45 6 .82 683.34 *58 .51 6 .88 683.40 *58.63 7 .00 683.52 *55 .60 7 .02 683.54 *55.83 7.25 683.77 *55 .97 7 .39 683.91 *56 .20 7 .62 684.14 *56 .32 7 .74 684.26 *56 .25 7.67 684.19 *56 .27 7 .69 684.21 *56 .30 7.72 684 .24 .*
*Backwater effect f rom ice bridge at LRX-43 and advanc i ng ice cover.
- 112 -
November 15
Locat ion
Sample Size 1 cubic foot
s2 /bb8
= 0 .67
= 0 .69
= 0 .69
= 0 .68
=0 .32
=0 .68
113 -
1 - 0 .69
Weight 39 .3 po unds of fraz il
57 .3 pounds sol id ice
Weight 39 .5 pounds of fraz il
57 .3 pounds solid ice
Weight 39 .0 pounds of frazil
57 .3 pounds sol id ice
Weight .38 .8 pounds of fraz il
57 .3 pounds solid ice
Sample S ize 1 cub ic foot
Sample'Size 1 cubic foot
November 18
Weight 36 .9 pounds of frazil = 0 .64
57.3 pounds sol id ice
Weight 39 .5 pounds of fraz il =0.69
57 .3 pounds sol id ice
January 5
TABLE 7.4
SUSITNA RIVER
FRAZIL ICE WEIGHTS
For Determ in ing Poros ity
POROSITY=
AVERAGE
Chu lit na Confluence
Octobe r 17
Gold Creek
October 17
Watana
Oc tober 17
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I s2/bb9
I
I T ABLE 7 .5
S US IT NA RIVER at GOLD CREE K
ICE DISCHARGE COMP UTATIONS
I Q j =C i \'~B1 t s (1-s)
I
Ice S u rface Channel S lush Ice
I Concentra tion Veloc ity Width Thi ckness Poros ity Discharge
Date C.(%)V (m/s)~1-!!!U.(m)3Q.(rn I S)--I -s --s--I--
I October
1983
I 1 0 1.5 106 0 .31 0 .0
2 0 1.5 106 0 .31 0 .0
3 0 1.5 106 0 .31 0 .0
4 0 1.5 106 0 .31 0 .0
I 5 0 1.5 106 0 .31 0 .0
6 0 1.5 106 0.31 0 .0
7 30 1.5 106 0.46 0 .31 15 .1
I 8 50 1.5 106 0 .46 0 .31 25 .2
9 50 1.5 106 0.46 0 .31 25 .2
10 35 1.5 106 0.46 0 .31 17.7
I 11 25 1.8 99 0.46 0 .31 14 .1
12 0 1.8 99 0 .31 0 .0
13 0 1.5 99 0 .31 0 .0
14 0 1.5 99 0 .31 0.0
I 15 5 1.5 99 0 .46 0 .31 2.4
16 30 1.5 99 0 .46 0 .31 14 .1
17 35 1.5 99 0.46 0.31 16.5
I 18 25 1.5 99 0.46 0 .3 1 11.8
19 5 1.5 99 0 .46 0 .31 2 .4
20 10 1.5 .99 0 .46 0 .31 4 .7
I 21 20 1.4 99 0 .46 0.31 8 .8
22 10 1.3 99 0.46 0 .31 4 .1
23 25 1.3 99 0 .46 0.31 10 .2
24 50 1.2 99 0.46 0 .31 18.8
I 25 75 1.2 99 0 .46 0 .31 28 .3
26 65 1.3 99 0 .46 0 .31 26.6
27 50 1.5 99 0 .46 0 .31 23 .6
I 28 50 1.5 99 0.46 0 .31 23.6
29 60 1.5 99 0 .46 0 .31 28 .3
30 35 1.5 99 0 .46 0 .31 16.5
I 3 1 30 1.3 99 0 .46 0 .31 12 .3
I
I -114 -
s2/bbl0
TABLE 7 .5 (cont .)
SUSIT NA RIVER at GOLD CREEK
ICE DISCHARGE COMPUT ATIONS
Q .=C.V B 1 t (1-)
I ISS S
Ice S u rlace Channel Slush Ice
Concent ration Velocity Width T h ickness Poros ity Discharge
Date C.(%)V (m/s)~1--l!!!l (m)Q.(m3/S)--I -s --s--I--
November
1983
1 50 1.5 99 0 .46 0 .3 1 23.6
2 40 1.5 99 0 .46 0 .31 18.9
3 60 1.5 99 0 .46 0 .::1 28.3
4 65 1.3 94 0 .46 0 .31 25. 2
5 75 1.2 94 0.46 0 .31 26 .9
6 75 1.2 94 0 .46 0 .31 26 .9
7 80 1.2 94 ·0 .46 0 .31 28.6
8 50 1.2 94 0 .46 0 .31 17.9
9 20 1.2 94 0 .46 0 .31 7 .2
10 20 1.2 94 0 .46 0 .3 1 7 .2
11 50 1.2 94 0 .46 0 .3 1 17.9
12 30 1.2 94 0 .46 0 .31 10.7
13 70 1.2 94 0.46 0 .31 25 .1
14 70 1.2 94 0 .46 0 .3 1 25.1
15 75 1.2 94 0 .46 0 .31 26 .9
16 55 1.2 94 0 .4 6 0 .31 19. 7
17 70 1.2 94 0 .46 0 .31 25.1
18 60 1.1 87 0.55 0 .31 21.8
19 70 1.1 87 0 .55 .0.31 25.4
20 70 1.1 87 0 .55 0 .31 25.4
21 40 1.1 87 0 .55 0 .31 14 .5
22 15 1.1 87 0 .55 0 .31 5.5
23 25 1.2 87 0.55 0 .31 9 .9
24 50 1.2 87 0 .55 0 .3 1 19 .8
25 55 1.2 87 0.55 0 .3 1 21.8
26 60 1.2 87 0 .55 0 .31 23.8
27 60 1.2 87 0 .55 0 .3 1 23.8
28 10 1.1 87 0 .30 0 .31 2 .0
29 10 0 .9 87 0 .30 0 .31 1.6
30 10 0 .9 87 0 .30 0 .31 1.6
-115 -
I s2l bb11
I
I TA BLE 7 .5 (cont .)
SUSIT NA RIVER at GOLD CREEK
ICE DISCHARGE COMP UTATIONS
I Q j =C":Vs B1 \(1-s )
I Ice Surface Channel S lush Ice
I Conce ntration Ve locity Width Th ic kness Poros ity Discharge
Date C.(%)V (rn/s )!!1--..J!!!l (rn)Q .(m3/S)--I -s --s--I--
I December
1983
I 1 10 0 .9 87 0 .30 0.31 1.6
2 10 0.9 87 0 .30 0.31 1.6
3 15 0.9 87 0 .30 0.31 2 .4
4 25 0.9 87 0 .30 0 .31 4 .1
I 5 15 0.9 87 0.30 0.31 2 .4
6 10 1.1 87 0.30 0 .31 2 .0
7 35 1.1 87 0 .30 0.31 6 .9
I 8 40 1.1 87 0 .30 0.31 7 .9
9 55 1.1 8 7 0 .30 0 .31 10.9
10 55 0 .9 87 0.30 0.31 8 .9
I 11 65 0 .9 87 0 .40 0 .31 14 .1
12 80 0 .9 87 0 .40 0 .3 1 17.3
13 80 0 .9 78 0 .40 0 .31 15 .5
14 80 0.9 78 0 .40 0 .31 15 .5
I 15 80 0 .9 78 0.40 0 .31 15. 5
16 80 0 .9 78 0 .40 0 .31 15 .5
17 60 0 .9 78 0 .40 0 .31 11.6
I 18 70 0 .9 78 0 .40 0 .3 1 13 .6
19 50 0 .9 78 0 .40 0 .3 1 9 .7
20 35 0 .9 78 0 .40 0 .31 6 .8
I 21 20 1.1 78 0 .40 0.31 4.7
22 50 1.1 78 0 .40 0 .3 1 11.8
23 50 0 .9 78 0 .40 0 .3 1 9.7
24 30 0 .9 78 0 .40 0 .31 5 .8
I 25 30 0 .9 78 0.40 0 .31 5 .8
26 40 0 .8 78 0 .40 0.31 6 .9
27 50 0 .8 78 0 .40 0 .31 8 .6
I 28 55 0.8 78 0 .40 0.3 1 9 .5
29 60 0 .8 78 0 .40 0 .31 10 .3
30 70 0 .8 78 0 .40 0.3 1 12 .1
I
31 50 0.8 78 0.40 0 .31 8.6
I
I -116 -
s 2lbb12
TABLE 7.5 (co nt.)
SUSIT NA RIVER at GOLD CREEK
ICE DISCHARGE COMPUTAT IONS
Ice Su rface Channel Slush Ice
Concentra tion Velocity Width Th ic kness Poros ity Discharge
Date C.(%)V (rn /s )~1~t (m)E Q .(m3/S)
-I -s -s --s--I--
January
1984
1
2 20 0 .8 78 0.3 0.31 2 .6
3 10 0 .8 78 0 .3 0 .3 1 1.3
4 20 0.6 78 0 .3 0 .31 1.9
5 50 0.6 63 0 .3 0.31 3.9
6 30 0 .6 63 0 .3 0 .31 2 .3
7 20 0 .6 63 0 .3 0.31 1.6
8 20 0 .6 63 0 .3 0 .31 1.6
9 20 0 .6 63 0 .3 0 .31 1.6
10 15 0 .6 63 0.3 0.31 1.2
11 5 0 .6 63 0 .3 0 .31 0 .4
12 5 0 .6 63 0.3 0 .31 0 .4
13 5 0 .6 63 0 .3 0 .31 0 .4
14 5 0 .6 63 0 .3 0 .31 0 .4
15 0
16 0
17 0
18 0
19 0
20 0
21 0
22 0
23 0
24 0
25 0
26 0
27 0
28 0
29 0
30 0
31 0
-117 -
I s 2/bb13
I
I TABLE 7 .6
SUSITNA RIVER
WATER TEMPERATURES DC
I
DENALI (RM 290.7)J AY CREEK (RM209 .5)WATANA (RM 183 )
I Date Min.Ma x .Mea n Min.Max .Mean Min.Max .Mean
September
I 1983
1 3 .5 7 .0 5 .3 6.1
2 4.6 3 .9 5 .8 4 .9 5.5 6.5 6 .0
I 3 1.8 4 .6 3 .2 3 .6 5 .0 4 .3 5.0 5 .8 5 .4
4 1.3 3 .0 2 .2 3 .7 5 .2 4 .5 4.3 5.5 4 .9
5 1.0 3 .5 2 .3 4 .3 5.0 4 .7 3 .8 5 .2 4 .1
I 6 0 .8 3.7 2 .3 4 .6 5.6 5 .1 3.2 5 .0 4 .1
7 1.3 3 .4 2 .4 4 .9 7.0 6 .0 3.3 4 .6 4 .0
8 2.0 4 .0 3 .0 4 .7 6.2 5 .5 4.0 5.2 4 .6
I 9 2.4 4 .0 3 .2 3 .9 5.2 4 .6 4 .2 5 .6 4 .9
10 2.4 5.0 3 .7 3.8 4 .6 4 .2 4.8 6 .2 5 .5
11 1.4 4 .8 3 .1 3.0 5.3 4 .2 4 .5 5.2 4 .9
12 2 .1 3.8 3 .0 2 .5 5.0 3 .8 4.5 5 .3 4 .9
I 13 1.8 3 .2 2.5 0 .5 6 .2 3.4 4 .6 5.0 4 .8
14 2 .0 3.3 2.7 0 .0 3.4 4 .1 3 .8
15 1.2 3 .1 2 .2 3 .0 6 .5 4 .8 3.7 4.7 4 .2
I 16 0.2 3 .2 1.7 4 .0 5.5 4 .8 2.8 4 .3 3 .6
17 0 .1 2 .9 1.5 4 .5 4 .9 4 .7 2 .5 3.7 3 .1
18 0 .3 2 .3 1.3 0.0 1.9 1.0 2 .0 3 .2 2 .6
I 19 0 .9 2 .6 1.8 0 .0 1 .8 0 .9 2 .4 3.2 2 .8
20 1.5 3 .0 2.3 0 .0 2 .5 1.3 3.0 4 .0 3 .5
21 2 .2 2 .9 2 .6 0.0 2 .0 1.0 3.8 4.5 4 .2
22 1.8 2 .2 2 .0 0 .0 1.8 0 .9 4 .2 4.6 4 .4
I 23 In ice 0 .0 0.0 0 .0 1.0 3 .5 2 .3
24 In ice 0 .0 0 .0 0 .0 0 .0 0.0 0 .0
25 In ice 0 .0 0 .0 0 .0 0.0 0 .0 0.0
I 26 In ice 0 .0 0 .0 0 .0 0.0 0 .0 0 .0
27 In ice 0 .0 0 .0 0.0 0 .0 0 .5 0 .0
28 In ice In ice Dewate red
I 29 In ice In ice Dewa tered
30 In ice In ice Dewatered
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I s2/bb14
I
I TABLE 7 .7
SUSITNA RIVER at GOLD CREEK
Water Tempe ratures DC
I
I Date Temperature DC Date Temperature DC Date Temperature DC
I Oct.Nov.Dec .
1983 1983 1983
I 1 1 0.2 1 0 .5
2 2 0 .3 2 0 .4
3 3 0.3 3 0.3
I 4 4 0 .2 4 0 .2
5 0 .8 5 0.2 8 0.3
6 0 .7 6 0.1 6 0.4
I 7 0 .5 7 0 .1 7 0 .2
8 0 .2 8 0.1 8 0 .1
9 0 .2 9 0 .2 9 0 .1
10 .0 .4 10 0 .1 10 0 .1
I 11 0 .7 11 0.2 11 0.1
12 0 .8 12 0 .1 12 0 .1
13 0 .5 13 0.1 13 0.1
I 14 0.2 14 0 .1 14 0.1
15 0 .6 15 0 .1 15 0 .1
16 0 .7 16 0 .1 16 0 .1
I 17 0 .8 17 0 .1 17 0 .1
18 0.8 18 0 .1 18 0 .1
19 0 .4 19 0 .1 19 0 .2
20 0.1 20 0 .1 20 0.3
I 21 0.4 21 0 .1 21 0 .1
22 0 .2 22 0 .3 22 0 .1
23 0.4 23 0 .3 23 0 .1
I 24 0 .3 24 0.1 24 0 .1
25 0.3 25 0 .1 25 0 .1
26 0 .4 26 0.4 26 0 .1
I 27 0 .2 27 0 .4 27 0 .0
28 0.3 28 0.4 28 0 .0
29 0.2 29 0 .5 29 0 .0
30 0 .4 30 0.5 30 0 .0
I 31 0.3 31 0 .1
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I
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1
'1
s 6 /mm95
FIGURE 7 .1
October 17.1983 . Ice cry st als obta ined f rom a slush ice raft.Th ese a re
cl uste rs of four t o f iv e ind ividua l crysta ls.This ice or ig inated f ar u ps tream
an d h as metamor pho sed int o t hese large particles with l ittle cohesi on between
gra in s .
FIG URE 7.2
December 28 .19 83 .An chor ice da m a t RM 142 .5.A ncho r ic e a ccumu late s o n
t he s ub s tra te a nd eff ecti v ely r a i ses t he water level.w hich su bs equent ly f loo ds
the su r roun di ng b ord er ic e a nd sn ow co ver .
'I R&M CONSULTANTS,INC••""0 ........O.Ot.OO'."..\............•_v ••o ••
- 120 -
SUSITNA JOINT VENTURE
F IGURE 7.4
J anua r y 5 .1983 .The e lev a ted s ta ge c rea ted by a nch or ice ca used bo rder ice
t o fr ac ture .T h e f r a gments dri ft e d do wns tre am a nd lodged .c r eat ing a b a rr ier
to i ncoming s l ush ic e .This br id ge o ccu rred a t RM 135.6.
I
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s6 /mm96
F IGURE 7.3
Dec ember 28.1983 .RM 130 lookin g up stream.I n 1983 th e
g ress ion end ed a t S he rma n (RM 135 ) .Oth er p rocesses t he n
rem a ini ng o pen wat er f reeze -up t o Dev il Ca n yon .
ice co v er pro -
d o mi na ted th e
I
I
~'ii-----------
R&M CCNSU LTA TS,INC.....0.........a.O~OI.TW ."'.v o ••
-121 -
SUSITNA JOINT VENTURE
II '"zctIII %...ct '"'"uzctII.a:a:
'"::)
C UI
Z
"'::)
a:
'"U%...
-UI cta:::)~u
z "'~"'~CUI
ct UI a:
~...~~UI
Q.II.::)
c('"~
C a:~UI
0 %
0 UI a:
~::)'"II.~0
UI a:
0
III
'"a:
::)...
U
c(
a:...
'"Z
c(
III
I
I
I
I-I(I),.
j
f-,
I
~-J...
I
:IE
I
I
I
I
I R&M CCNSULTANTS,INC•..........._1lI.~•••-w-................_.uav."OII.
FIGURE
~22
7.5
SUSITNA JOINT VENTURE
I
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I
I
I
I
I
I
s6/mm98
REFERENCES
Alaska Department of Fish and Game ,1982 Susitna Hydro Aquatic
Studies ,Phase II Basic Data Report .Anchorage ,Alaska .
5 Vol .
Michel,Bernard,1971.Winter Regime of Rivers and Lakes.U .S .
Army Corps of Eng ineers ,Cold Regions Research and Engineer-
ing Laboratory,Hanover,New Hampshire .130 pp .
Newbury,Robert W.1968.The Nelson River :A Study of Subarct ic
River Processes .University Microfilms ,lnc .,Ann Arbor,
Michigan .319 pp
R&M Consultants,Inc . ,1981 Ice Observations
1980-1981 .Anchorage,Alas ka.Alas ka
Power Authority .Susitna Hydroelectric Project.
Report of Acres American ,Inc .1 Vol.
1982 a.Ice Observations 1981-82 .Anchorage,Alaska.
Alaska Power Authority.Sus itna Hydroelectric Project .
Report for Acres American,Inc .1 Vol.
1982 b.Processed Climatic Data,October 1981 to
September 1982 .Anchorage,Alaska.Alaska Power
Authority .Susitna Hydroelectric Project .Report for
Acres American ,Inc .8 Vol.
1983 a .Susitna River Ice Study 1982-1983.
Anchorage ,Alaska .Alaska Power Authority.
Susitna Hydroelectric Project.Report for
Harza-Ebasco Susitna Jo int Venture .1 Vol.
1983 b.Processed Cl imatic Data,October 1982
to September 1983 .Anchorage,Alaska.Alaska
Power Authority .Sus itna Hydroelectric Project.
Report for Harza-Ebasco Joint Venture .6 Vol.
U .S.Geolog ical Survev , 1983.Water Resources Data ,Water
Year 1982 .Anchorage,Alaska.Water Resources Division,
U.S .Geological Survey.United States Department of the
Inter ior .
123
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I
APPENDIX A
MONTHLY METEOROLOGICAL SUMMARIES
FROM WEATHER STATIONS AT DENALI,WATANA,
DEVIL CANYON ,SHERMAN AND TALKEETNA
I ...
1l(A Sfe ca lUu el NET OIST
1
I
1
\(."13
UU:EE TU .ALU la
UL I([T"l l ltPORt
2~1 2 1
-LOCAL
CLIMA TOLOGICAL
Monthly Summary
[L(Ull DII •'lOtIO 1 ]415 f U T
DATA
1t9l(101£"LAS IU ......U'5 21
I E.PE RAT URE 'r OUIU Din .to "to "'IS ','I':'II I1 Ia MIND SUISMII(Sly CD.(I
I IS[U·f Nl:UPI 111'II ::",U.1".P .M .J lUI'IlSI1,os or e'lls s_
~s ~=2 Ion F05 00 ~..~!D fA,'.',"-]IMUl D(lSIOIII IC[01 ~-'••5 a 0~:::;-~I ~•-•1[['[LL £tS i'OnD :0 ;;c ::=~;:-~_.~-5 MIll II mi.••~•o~-~aa -;!;;~0 1 ::.
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a a -=,,=~-~•~_0 ~o _0 c0• •
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2 ~o 31 "·2 II "Q 1 0 I 0 !.H ,<.2 <.1 10 27 l <2
3 ~O 31 "-2 II "0 0 I 0 '.23 <1.1 3 .2 1 21 ,I 3
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0 ,."~O .<2 .,,2'0 0 "•11 II 2'II -I 33 24 0 0 0 0 ,."11 1.3 3 .3 7 "0 0 11
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23 II 21 31 -I 21 30 0 1 T .10 1.0 .:.2 0 ~I.',.s 11 03 1 7 23
24 33 22 21'-u 11 31 0 0 0 0 ,:.31 2 10 .0 10 .,21 03 I .2<I
21 31 2<31 -11 T3 l4 0 0 0 0
,...2 '.1 ,.,21 02 3 2
21 I
H 42 11 30 -1 2 II 31 0 0 0 0 ,."<<.2 ~.I I n 0
l\I2740"30 -11 31 0 0 T I 11 03 ,
21 31 31 l4 -I l4 31 0 T .".1 ,.",1 .1 ,.1 10 II '0 21
l'<2 31 <.0 .3'21 0 T 0 1 .12 0 '..,1 1 .1 ,.,T2 02 10 2'
30 I I ""1 <3 "0 ,0 .32 0 '.22 "7.1 1 .2 17 11 10 ,lO
"'I",o Il I •lutllU Of DUS Oil "01 I II 1101111 :lOll ,I ",'"'1 1 '...,...,.".
D['II .o •!'EmIlAIII <•U :Iftllk.."..,a".
<-»01 lie,.17 -
lultiE I or ons 1 0" 0 011 \....IE''LL""U(I1£$1 I I 14 "'S 110 DItU "UI[51 O£,IM 01 ,IOUID oro ,DIAL )1.0 11C M 1 S.....1(['Ell [tS 01 1(["0 Dltt""I"UIl I 1111 1111 IIlU"•1 1 'v'I '"S "I I •I •...IC,,o ••It .n ,I -I <-.
0 I 1 < C
..I •t uO 'ou •
II
1
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•EIl REoE r OR THE OONIU -LAST OC CURRENCE Ir OORE THAN ONE .
r TRACE AOOU NI .
• ALSO ON EARL I ER DATE l SI.
HEA VY FOG :VI SIBI LITY '/4 OI'E OR LE SS .
B'ANK ENTAIEI DENOTE NISS ING DR UNREPOR TE D DATA .
HO URS Dr DPS.•AT BE REDUCED ON A VARIA BLE SCHEDULE.
I
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OU A IN COLS &AND 12-15 ARE BAS ED ON 7 DR OORE OBSE'V ATIONI
AT 3-HOUR I MTER VALS .RE SU,TANI "IND IS TH E VECTOR IUO or 'IND
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SUSI"TNA HYDROELECTRIC PROJECT
MONTH LY SUMMARY FOR SHERMAN WEA TH ER ST ATION
DATA TAK EN DURING SeoteMb er ,1983
RES.RES.fWG.IlAX .IIAX .DAY 'S
IIAX ."IH.IlEAIl YINO YIND YIND GUST GUST P'VAL ItEAH IlEAH SOLAll
lAY TEIlP •TEIlP •TEIlP •DIR .SP O.SPO .OIR .SPO .DIR .RH or PREClP ENERGY DAY
DEG C DEG C DEGC BEG ",S "IS !lEG ",S %DEG C IlII IIll/SQII
I 12.4 5.B 9.1 19..2 .It 281 3.B SSiI 94 B.7 2.B \37,I
2 15 .3 -.9 7.2 1411 .4 .5 145 3.2 N 3B -.1 1.0 5145 2
3 11t.5 -1.5 7.5 123 .2 .5 341 2.5 EIlE 48 3.1 1.1 3Z91 3
4 13 .1 -2.3 5.4 1l1li .4 .4 194 3.B ME 42 -1.0 1.0 211t3 4
5 14 .2 -3.It 5.3 m .1 .5 195 3.2 IN 37 -1.1 0.1 4348 5
It \5.0 -4,3 5.4 152 .2 .5 184 3.B IIMII 31 -4.1 1.1 4ItZ5 It
7 14.7 -3.7 5.5 215 .1 .It 192 3.B HIlII 4B 1.9 0.1 3553 7
B 12.B 3.B B.3 Z5B .2 .4 227 3.2 SSII 01 5.\.2 2093 B
9 14.0 4.7 9.7 230 .3 .It 222 4.4 H 55 4.4 .2 3211 9
II 15.1 .9 B.O m .2 .4 152 1.9 HHII 54 4.5 .4 2408 II
II 15.5 1.0 B.3 294 .2 .3 25S 3.2 SSlI 51 3.7 1.1 2398 II
12 14.8 3.3 9.\229 .5 .0 245 4.4 SlI 54 3.0 1.1 23 BB \2
13 12.9 1.5 7.2 151 .•3 .4 071 3.2 EI£65 4.8 1.1 2231 13
14 7.5 .1 3.B IBIt .3 .7 203 3.B S 90 4.7 .0 \113 14
15 11.9 -3.7 4.1 DIS .3 .5 I2It 4.4 Y 54 1.4 1.0 2953 IS
lit 15.7 -4.8 5.5 037 .4 .0 249 4.4 HIN 39 -.0 1.1 3815 10
17 12 .B -5.1 3.9 219 .4 .7 224 4.4 IISlI 43 -.\0.0 309B \7
\B \3.5 -4.B 4.4 132 .3 .5 121 3.2 E 5\.2 1.1 2530 \B
\9 12.1 -3.1 4.5 039 .9 1.1 049 b.3 NJ£53 \.b G.D 1431 19
20 B.B 5.0 0.9 133 .4 .4 145 2.5 HE 91t 5.\3.B 090 2'
21 12 .2 5.9 9.\m .2 .4 104 2.5 N Bo 9.\0.1 \533 2\
22 U .3 5.\m .2 .7 217 4.4 NHII 74 -4.D .4 IIIB 22
23 3.4 -2.0 .4 055 \.4 1.5 14B B.9 HE 411 -\0.3 1.1 2335 23
24 -.0 -3.4 -2.1 lSI 3.2 3.3 15 \9.5 HE 42 -13.0 0.0 2205 24
Z5 3.7 -9.2 -2.B 154 2.1 2.\140 7.0 HE 37 -13.0 1.1 32 83 Z5
ZIt 3.9 -11.0 ·-3.9 007 1.0 1.\157 5.\ENE 39 -11 .2 1.0 3085 20
27 3.It -\1.1 -3.8 159 1.1 1.0 107 4.4 ENE 40 -9.D 0.1 1948 21
28 I.B -.9 .5 034 .0 .0 115 2.5 MHE B9 -1.4 .2 59B 2B
29 3.4 .2 \.B IIt3 .4 .5 339 1.9 EIIE '1 Hit..B.I 413 29
30 10 .2 2.3 b.3 223 I.G 1.3 230 7.1 SIl B5 b.I 4.2 13b3 30
lIOHTIf IIt.S -11 .b U lSI .3 .B 051 9.S HE 52 -.\20.B 74033
GU ST I)EL .AT MAX .GU ST MINU f 2 INTERVA LS 8 .3
GJ ST I)EL.AT HAX.GUST MINUS 1 I NT ERVAL 8 .3
GUS T VE L.AT MAX .GUST PLUS 1 INTERVAL 7.0
GUST VEL.AT MAX.GUST PLUS 2 INTE:RVALS 8 .9
NOTE:RELATIVE HUMID ITY READI NGS ARE UNRELIABLE WHEN WIND SPEEDS ARE LESS THAN ~l
ONE METER PF.:R SECON D.SUCH READINGS HAVE NOT BEEN INCLU DED IN THE DAIL Y
OR MONTHLY MEAN FOR RELATIVE HUMIDITY AND DEW POINT .
It ·lt*·lt SEe:NOTES AT THE BACK OF TH IS REPORT ·It·lt·lt *
I (.j (i}
.#
,~s:M CDN~:>UI...TANT S .:J :N C.
I SU~:>:J:TNA HYnl~D EI,..E CTI~:J:C p I ~O.T ECT
I MONTHLY SUMMARY FOR S HERMAN WEAT HER STATI ON
DATA TAK EN DUR I NG Octob er ,1983
I RES .RES .AIIC.IIAX.1lAX.DAY'S
!lAX."Ill.~lltND litHO WIND CIlST GUST P'VAL IIEAH IDN SllAR
I DAY TEIlP •Tm.TEIIP •DIR .SPD .SPD.DIR .SPD .DIR.RH DP PRECIP EllERGY DAY
DEC C DECC DEC C DEC "'S ",S DEC "'S Z DEC C Hfl WH/SlIIl
I 1.9 2.4 S.2 206 .5 1.1 20 9 5.I SSll ao 2.S 2.2 1431
2 10 .3 -.3 5.0 D49 1.3 1.3 861 1.0 NE 5-4 -1.S .4 1825 2
3 1.9 -3.2 2.4 863 1.1 1.2 844 S.1 NE 31 -9.I 0.1 2501 3
I 4 9.I -6.1 1.2 015 .3 .S 884 2.5 E 32 -8.8 0.0 2403 4
S 3.6 -I.I 1.3 049 .2 .3 97t t.9 E 63 -3.3 0.0 591 S
6 S.2 -1.9 -1.4 13S .3 .4 138 3.2 S 66 -S.3 .2 191b 6
1 .9 -11.1 -5.4 116 .6 .1 141 3.2 EJlE 36 -13 .I 0.0 2231 1
I 8 1.1 -13.4 -6.2 159 .6 .1 060 3.2 EJlE 40 -13.I U 1955 8
9 -1.3 -3.4 -2.4 141 .9 .9 153 3.8 lIE B6 -4.4 1.1 225 9
tD t.I -1.2 -.I 132 .2 .3 871 1.9 H II I ....2.0 365 II
I II 7.4 .5 U 115 .2 .8 208 4.4 ENE 83 2.1 3.4 1445 II
12 4.5 .S 2.S ZC6 .5 .7 215 3.8 SSll C5 .8 2.2 955 12
13 3.S -4.2 -.4 m .2 .4 149 t.9 H B7 -3,8 .4 945 13
I 14 3.0 -8.1 -2.5 054 .8 .1 059 2.5 NE 81 -8.3 0.0 2125 14
15 3.4 -3.1 -.2 154 1.2 1.8 169 5.1 lIE 53 -1.0 0.1 1121 15
16 3.I -4.&-.8 060 1.4 1.5 ISB 5.1 ENE 52 -9.1 c.c 1111 16
17 1.2 -4.4 1.4 151 .9 1.0 874 4.4 NNE 58 -6.1 1.1 1401 11
I 18 6.S -1.3 2.6 060 .9 .9 163 3.8 ENE 51 -4.&0.0 1611 18
19 .2 -6.1 -3.3 123 .8 .9 0D:l 3.2 HNE 69 -6.4 0.1 S61 19
20 .1 -6.1 -3,3 036 .6 .1 02 0 2.5 NNE 19 -6.8 0.0 331 21
I 21 3.8 -2.9 .5 044 .1 .1 115 3.8 NE 13 -3.1 U 551 21
Z2 5.4 -7.2 -.9 163 •I .7 22 4 5.7 NNE 65 -4.2 ~1310 22..
23 3.4 -11.7 -4.2 D91 •3 .6 815 4.4 ENE 63 -6.5 1.1 1m 23
I 24 I.S -12 .I -5.3 055 .9 t.t 832 3.8 ENE 49 -11.2 1.0 99S 24
25 -.2 -13.2 -6.7 052 .9 1.0 066 5.I E 47 -14 .5 Q.l 1301 :!S
26 1.7 -11.4 -4.9 221 .5 1.4 209 7.0 ssw 67 -9.8 0.0 928 26
27 2.6 -9,3 -3.4 050 1.1 1.2 048 S.I HE 55 -8.8 0.1 955 ':!JI282.0 -2.7 -.4 080 ~.9 220 5.7 ssw 62 -&.3 0.0 550 ZS..
29 -2.0 -9.0 -5.5 III 1111 .4 H I 1111 III II I IIlII 1.1 325 29
30 •I -7 .0 -3.5 19&.8 .9 199 3.2 ssw 88 -3.5 n.o 2b5 30
I 31 -1.9 -6.2 -4.\216 .3 .1 219 3.8 ssw 36 -4.7 0.1 23S JI
MONTH 11 .3 -\3 .4 -1.2 061 .5 .8 061 1.1 ENE 62 -6.2 11.0 35574
I GU ST 'JEL.AT MAX .GUST MI NU S 2 I NTF.R VAI.S 5 ·.j7
GU ST VEL .AT MA X.GU ST MINU S 1 IN TER VA L 5 .7.
GliST VEL .AT MAX.GUST PI.U S 1 IN TERVAL 5.1
GUST VEL.AT MA X.GUS T P LU S 2 I NT ERV ALS ..~'",.
I NOTE:REI.ATIVF.HUM TPlTY RE APINGS ARE UNRE'LJ AB LE ~H-lF.N WI ND SPEEDS A r~E'1.E SS THAN
ONE METER PER St:CON1).GUCH Rr::A1)I NG S HAVE NOT BE EN I NGLU n r::T)IN THe:DAILY
I OR MONnll Y MF.AN F OR REL ATIVE HUM IPITY AND DEH POl NT .
I
I ~
(~)
,~M C Cl N B U I...TAN T B _:1:N C .
B U BI T N A HYDRCl EI...EC'"RIC PRCl3EC 'Y"
MONTHLY S UMM ARY F OR SHE RM AN WF.A THER STATI ml
DATA TAK EN DUR ING NoveMbe r .1 983
RES .RES .AIIG.1lAX.!lAX.DAY 'S
"AX."IN.tl£AH IIIND 1I1HO IIIND GUST GUST P'VAL IlEAH "EAH SOLAR
DAY TEllP •TEIll'•TElIP •DIR.SPD .SPD .OIl.SPD .DIR.RH OP PRECIP ENERGY DAY
OEGC DEG C DEG C DEC "IS "IS DEC "IS I DEC C M lIH/Sllll
\-.6 -9.5 -5.\041 .8 .9 149 3.8 HE 8\-6,5 U 271 \
2 4.2 -7.1 -1.4 064 .8 .9 059 3.8 ENE 67 -4.0 .4 m 2
3 3.5 -9.4 -3.0 O~.9 t.Q .045 3.8 ENE 82 -6.J 0.0 1025 3
4 -1.8 -10.5 -6.2 079 .7 .8 O~3.8 E 84 -9,7 0.0 640 4
5 -1.4 -\4.3 -7.9 D72 .4 .5 047 1.9 E &\-8.7 0.0 930 5
&-8.4 -\7.3 -\2.9 0&5 .4 .4 076 3.2 EllE H H *H 0.0 6&5 &
7 -1.&-\0.3 -&.0 047 1.2 1.2 05\4.4 HE &9 -9.\0.0 4&1 7
8 2.7 -3 .6 -.5 036 .9 \.0 040 3.8 HHE 67 -6.1 0.0 485 8
9 4.3 -3.2 .6 06 \1.\\.2 m 4.4 Ell E 4&-\0 .0 0.0 745 9
\0 2.9 -3.\-.\0&3 \.2 \.3 069 3.8 ENE 48 -9,9 0.0 595 \0
11 .9 -9,\-4.1 151 1.0 \.0 071 3.8 ENE 59 -9,7 0.0 555 11
\2 -\.4 .-7.5 -4.5 162 .6 .6 038 2.5 E &0 -\0.2 0.0 385 \2
\3 -6.J -\5.4 -\0 .9 077 .6 .6 071 2.5 EllE 92 -H .I 0.0 491 \3
\4 -7,3 -\7.8 -\2 .&152 .6 .6 050 2.5 HE 90 -12.7 0.0 m \4
\5 .3 -13.9 -0.8 055 .9 1.1 045 3.2 ENE 69 -9,3 0.0 47 5 15
\6 -2.2 -10.&-&.4 050 .7 .7 151 3.2 HE 88 -7.1 Boa 400 1&
17 -6,9 -\5.4 -1\.2 0&8 .6 .6 0&2 2.5 ENE H HHI 0.0 3ia 17
\8 -&.5 -17 .6 -12 .\057 .6 .7 037 2.5 EN E 69 -\1.&0.0 40S \8
19 -15.1 -21 .2 -\a.\064 .3 .3 059 1.3 ENE H HIH 0.0 345 \9
20 -2.4 -20.&-11 .5 as?.7 .7 052 3.2 ElIE 82 -7.0 U m 20
2\3.4 -2.0 .7 054 .a .9 049 5.\EliE &9 -4.&0.0 305 21 I'22 .t -4,5 -2.2 057 1 .3 069 1.3 ENE H UH*0.0 2\5 22.~
23 -3.4 -9,9 -&.7 059 .3 .3 035 \.9 ENE H IIHI 0.0 285 23
24 -7.4 -\9 .6 -\3.5 052 .t .t 3\0 1.3 ENE H lUll 0.0 235 24 I2:5 -6.7 -\7.5 -\2 .\026 .3 .3 03\3.2 NHE 82 -\0 .\0.0 255 25
2&-4.4 -9,3 -6,9 m .8 .8 024 3.2 NNE 77 -9,6 0.0 2&0 2&
27 -2.5 -8.a -5.7 050 .7 .7 02\2.5 HE 9&-4.8 0.0 245 27 I282.&-4.1 -,8 055 U 1.0 054 3.8 £liE &9 -3.9 0.0 285 2B
29 U -V .3 05 4 .a .9 046 2.5 Nt 73 -4.7 0,0 290 29
30 3.4 -7 .0 -1.8 057 ,7 ,7 051 3.2 HE 61 -6.4 0.0 2BO 30
nONiH 4.3 -21.2 -~.3 055 .7 .7 049 s.i Ell E 67 -8.2 .4 130 33
GUST vst.,AT MAX.GUS T MIN US ':>INTERVALS ':>.:-
~~,.J
GUST 'v'EL.AT MAX . GUST MINU S 1 I NT ERVAL 3 .8
GUS T ll EI..AT MAX .GUST PLUS 1 INTERV AL.5 .1
GUST vsi..AT MA X.GUS T PLUS ':>INTERVA LS 5.1,-
!'l OTF.:~E LA Tr'.)F.HUMI DITY READINGS A!(t UNRELIA BL E WHEN I,H NfJ SP EEDS i~I~E LESS TH AN
ONE MF.:TER PF.:R SE:C O~ID .S UC H RF.:AD I NGS HA VE NOT B EF.:~1 INCLU DED I N THE DAL ''(·1
OR MONTHI ..'(ME AN FO R RELATIV E HUM IDITY AND DEW POINT.
Ai ·X-:k .)(-SEE NOT E:S AT THE BA CK OF TH IS RF.:?OR T ·x,·x··~·x,
7
2
265
281
265 3
170 4
155 5
245 6
291
255 9
281 ?
291 1D
265 11
241 \2
215 13
215 14
271 15
255 16
\71 17
215 IS
191 19
\81 ~I
175 21
Z20 ~
245 23
251 24
291 25
241 26
251::1
255 2ft
265 29
265 31
241 3 \
74D5
DAY'S
SllAR
EIOCT DAY
IlIVSIlII
1.1
1.1
'.1I.'
1.1
'.1
'.1
O.P
8.1
1.1'.1
I.D
1.1
1.0
0.1
1.1
1.1
1.1
1.1
0.0
1.1
0.1
1.1
1.1
1.1
1.1
1.1
U
1.1
0.1
1.1
0.1
3 .8
4.4
3.d
4.4
PRECIP
""
P I ~O :rECT
I1£AII
DP
DEH
..11111
..1"11
-\3 .5
2 INT ER VA LS
1 HH ERV AI.
1 INT ERVAL
2 INTERVA LS
ENE
ENE
ENE
3.2 HE
4.4 ENE 71
1.9 lIE ..
2.5 ENE II
3.8 HE 7J
3.2 ENE 85
2 .5 ENE 93
1.9 ENE 91
2.5 ENE II
1.9 ENE II
I.9 ENE ..
1.9 ENE II
1.9 EIIE II
4.4 lIE 67
2.5 ENE 77
I.9 lIE 91
I.9 tIE II
1.3 NE ..
t.J llHE
\.9 ENE
5.1 EII£71
1lAX.
GUST P'VAl nEM
SPD .DIR.R1I
ntS Z
IIAX .
J;UST
DIR.
DEC
MINUS
MINUS
PI.U S
PLU S
.7 164
.3 175
•I 159
.2 146
.2 162
.2 .61
D.I 025
...134
.4 D49
1.8 166
\.6 lSI
.9 138
1.1 166
.3 '145
.2 D72
.8 159
I.D 159
.7 175
.5 165
.6 C51
.5 146
.5
.4 161
.6 174
I.I 139
.8 153
.4 182
.4 0C9
.3 042
•I OllS
.6 139
.6 11>6
AUG .
WIND
SPD.
nlS
GUST
GUST
GUST
GU ST
.7
.2
.t
~.~
.3
.2
1.1
0.0
.4
1.8
1.6
.8
.9
.3
.2
.8
.9
.7
.5
.5
.5
.5
.3
.6
1.1
.8
.4
.3
.3
.I
.5
.5
RES.
WIND
SPD.
nlS
E,~TcC)N~:>U I...TA NT ~:1 _
H Y D I~C)E J...E,:C T I~:1:C
RES .
WIND
DII.
DEC
AT MAX.
AT MAX .
AT MAX.
AT MAX.
-.5 159
-5.7 12b
-5 .1 042
-5 .8 152
-3 .\153
-6 .1 17\
-13.2 III
-16.1 II'
-\7.9 O~
-\0.3 070
-7.0 067
-11.7 046
-9.9 059
-18.6 157
-22.\072
-15.\054
-IU 152
-\2.8 151
-12.2 167
-5 .2 164
-4.1 059
-12.\062
-\8.9 157
-\4.5 066
-4.7 15\
-12.4 181
-\7.8 152
-22.3 044
-23.9 057
-22.I 05\
-13.3 154
-\2.I 059
'v'EL .
VEL.
'v'EL.
'.)(L.•
I~
-3 .I
-8.5
-6.5
-8.8
-3 .8
-10 .7
-15.6
-21.6
-22.9
-14.5
-9.5
-16.I
-14.3
-21.2
-25.7
-17.7
-12.6
-17.8
-17.5
-7.\
-5.S
-19 .9
-21.3
-19.5
-11.1
-11 .1
-22.2
-23.9
-26.0
-27 .3
-\6.3
-27.3
GU ST
GU ST
GU ST
GU ST
1lAX.nlll.IlEAH
DAY T£II'•IDIP .TEIlP •
DEC C DEC C DEC C
I 2.2
2 -2.9
3 -3.4
4 -2.8
5 -2.4
6 -1.5
7 -11.7
8 -11.4
9 -12.9
10 -6.I
II -4.5
12 -7.2
13 -5.5
14 -16.0
15 -18.4
16 -12 .5
17 -8.5
18 -7.1
19 -6.8
20 -3.3
21 -2 .2
22 -4,3
2:l -16.5
24 -9 .4
25 .6
26 -7.7
27 -13.J
28 -21 .1
:!9 -21.1
30 -lb.7
31 -11 .2
IIONTH 2.2
I.
I
I MONTHL Y SUMMARY FOR S HE RMAN WEATHER STATTON
DATA TAK EN DU RING D e ~p.M b e r ,1 983
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I NOT E :RELATIVE HUM IDITY R EADI NG~ARE UNRE I_I ARLE WH EN ~II N D S PFf DG
ONr METER rE R SECOND.S UC H REAOINGS HAV(NOT BEC N INCLUD EO
OR MONTHLY MEAN FOR RELATIV E HUM IDITY AND DEW POINT.
AR E I.F.S r:TIIA N
HI TIlE DA I LY
I ~..(.~c 0 N C:'lJ I 'T'A N 'T'<:'().\.N c".""X •.r _...:)0 _.....,.....__
S USIT N A H Y D R OELE C T R IC PRO J E C T
MONTHLY S UMMARY FO R DEVIL CANYON WEATH ER STATI ON
DATA TAKEN DU RING SepteMb er ..1 9 83
IES.IES .iWIi .IIAX .I!AX .DAY'S
IIAX."IH .IlEAll WIND WIND WIND GUST GUST P'VAL 101I IlEAIl SOI..AIl
DAY TEIlP •TEIlP •TEIlP •DlI .SPlI .SPlI .1II1 .SPlI .DlI.RH lIP PRECIP EIlERGl DAY
DEC C DEC C DEC C DEC illS'illS DEC illS %lIECC I1Il lIIII~llll
I \1.2 5.&7.9 m .•1 .8 27 4 .5.1 EIl£14 -21 .3 1.0 1081 I
2 12 .1 1.0 &.&14&.3 \,1 1\&3.8 SE 3&-1G.1 '.0 4495 2
3 \3.1 .&&.8 088 .9 \,3 297 4.4 E &&.1 I.Q 2748 3
4 8.9 -\'1 3.9 179 .8 \,3 119 5.7 ESE &9 -2,4 1.0 22&4 4
5 1\.&-3.0 4.3 1\9 .5 \,3 231 4.4 E &5 -3 .1 1.0 3498 5
&I\,4 -2.1 4.7 187 \,.1.5 114 •S .I E 38 -12.2 0.1 4280 &
7 1\.1 -n .s .3 0&5 .&\,1 147 :U .lIE 72 -1.2 1.0 2&81 7
8 9.&3.8 &.7 170 .1 .8 248 .~ESE 53 -9.2 0.0 1&&8 8J.~
9 1\.8 3.5 7.7 :m .3 .9 310 3.8 WIN 5&-3.1 1.0 1895 9
\I 1\.7 3.7 7.7 144 .2 .7 157 2.S SE &0 -5.7 1.0 189 5 10
\I 13.1 3.2 8.1 .&9 .7 1.1 191 4.4 £HE SO -4.7 1.0 2143 \I
12 11.5 3.7 7.&31 &.&\,3 319 5.7 IlNY 71 3.2 I.'21 83 12
13 11.1 2.7 &.9 193 .9 \,2 113 5.7 E 49 -5.8 I .a 28\Q 13
14 &.4 2.&4.5 245 .5 \,0 2B2 5.1 SSE 39 -15 .3 1.0 1403 14
15 8.9 -\,&3.7 23B .3 1.1 019 4.4 Y 7&.4 o.a 2385 15
1&12 .5 -3.1 4.8 111 .&\,2 GOO ~.i E 50 -7.2 I.'3173 1&
17 11.1 -2.&3.7 ISS .1 \,3 27&4.4 E &8 -\'9 1.0 3aB5 17
18 11.3 -8.4 \,5 191 1.1 1.4 ISS 3.8 £HE &8 -2.4 1.1 2705 18
19 9.4 -.2 U \19 1.3 \,5 094 5.1 ESE &&.4 0.0 144 3 19
20 8.7 3.&&.2 121 .2 .5 141 \,9 E 13 -21.8 1.0 903 2D
21 1\,3 5.7 8.5 189 .3 .8 138 2.5 E 13 -20.2 0.0 1&08 21
22 7.3 -.9 3.2 22J .4 \,1 033 5.1 Y 17 -19 .2 1.0 1285 22
23 -.1 -5.8 -3.0 089 1.7 2.1 041 8.9 £HE 54 -I\,4 0.0 1;!28 23
24 &.4 -9.3 -1.5 035 \,9 2.4 028 9.5 £HE 51 -13.&1.0 2351 24
2S -.8 -6.7 -3.8 183 2.0 2.&143 10 'Z ESE 45 -14.2 1.0 2847 25
2&1.1 -8.9 -4.5 13&\,&\,8 11 8 &.3 S 50 -12.4 1.0 30 48 2&
27 .&-9.0 -4,2 098 \,4 \,7 0&1 5.7 E 53 -10 .5 0.1 2183 27
2B 2.1 -2.8 -.4 092 \,2 \,3 081 5.1 E &&-8.7 1.0 10 15 28
29 3.7 .1 1.9 120 .9 1.1 11&3.2 ESE 28 -20 .0 0.0 i>:ia 29
30 7.3 2.4 U 10 8 .4 1.0 121 3.8 E 17 -23 .2 0.0 1090 3D
IIOHTH 13.0 -IU U 093 .5 \,2 143 I e .;ESE 52 -9.2 U &4 543
GUST IJEL.AT MAX.GUS T MINU S 2 IN TERVALS 8 .9
GUST VI::L.AT MAX .GUST MINU S 1 ItHI::RVAL 5 .7
GUST I')EL.AT MA X.GUST PLUS 1 INTERW\I_3.2
GUST VEL.AT MAX.GUS T PLU S '"INTERV ALS 3 ",<-•<-
NOTE :RE LATI VE HU MIDITY REA DINGS AR E UNRELIABLE WHEN WIN D S P EEDS A I~E LESS TH AN
a NI::MI::n:.:~PER SECON D.SU CH RI::AD IN GS HA VE NOT B EE ~I INCLU DED IN TH E DAIL l'~t,OR MO NTHLY MEAN FOR RELATIV E HUM IDITY AN D DEW P OI NT .
,io':l'o ;" ':'SEE NOTE S AT THE BACK OF TH IS RF.:PORT '~'Jt .~.~
I (~.(..."-.•.
,~~.M C O NS I...II...TI~NT S ":J:N r :~.
I S US:I:TNA HYD1~c)EI...ECTI~:I:C P ,~0 ,~I'E C T
I MO NT HLY S UM MAIH FOR IlEVIL CANYO N WEATH ER !:;T ATJON
OAT A TA KEN OURING Oc r o b er-..1 983
I RES .RES.AUG ./lAX."AX .PAY 'S
!lAX ."IN .IlEAN WIND WIND ~IND GUST l:UST P'WtI./lEAN IlEAN WI
I DAY TEIlP •TEIlP.TEIlP •DIR.SPD.SPD.DIR .SPD .DlR .RH DP PRECTP EIOCT DAY
DEG C DEGC DEC C DEC "'S "'5 DEC ",S %IEGC IlIJ WHlSllIl
I 1 5.8 ,3.1 289 .5 .9 1«3.8 IISll 17 -22 .4 0.0 988..
2 7.7
,4.1 lI8 .6 1.1 112 8.3 SE 60 -2.5 0.0 1548 2..
3 4.4 -3.0 .7 IBJ 1.2 1.8 121 7.6 ESE 57 -I"b 0.1 1881 3
I 4 6.6 -4.1 1.3 110 .7 1.2 145 4.4 [68 -b.7 0.0 1987 4
5 2.2 -l.b .3 abb ••.6 162 ~.5 [NE 72 -4.9 0.1 711 5
s 2.2 -8 .3 -3.1 lI9 .7 .8 111 3.8 SE 80 -7.6 0.0 1497 6
7 -2.3 -11 .9 -6.6 lI4 1.6 1.9 101 5.7 [~-lI .5 '.1 1m 7I8 -.8 -13 .2 -7.0 098 1.6 1.8 087 4.4 SE 69 -12 .1 a.o m l 8
9 -2.4 -5.2 -3.8 089 1.0 1.1 07'1 3.3 [55 -18.2 0.'63.9
11 1.8 -2 .8 -.9 no .3 .3 076 3.2 [18 -2t.6 0.0 350 10
I II 7.7 .1 3.9 211 .6 .9 254 b.3 5 19 -24.6 1.6 1341 11
12 3.8 -.2 1.8 182 .3 .8 232 3.2 E 16 -25.2 .2 805 12
13 1.5 -5.6 -2.1 J34 .1 .5 302 1.9 NNE II -29.5 1.1 431 13
I 14 -.5 -10.0 -5.3 131 1.1 1.3 132 3.2 SSE 45 -21.1 1.0 1470 14
15 .8 -7.0 -3.1 104 1.5 1.5 095 4••ESE 68 -5.2 I .'831 15
16 .4 -8.9 -4.3 103 2.1 2.1 088 7.1 ESE 71 -6.8 1.0 lI~16
17 5.1 -5.1 '.0 132 1.2 1.4 lI2 3.8 SE 74 -3.9 U 1171 11I183.4 -1.1 1.2 102 1.5 1.6 074 4.4 [SE 81 -1.4 Q.G 1215 19
19 -.1 -3.5 -2.1 111 1.2 1.3 oas 4.4 E 88 -7.1 1.1 555 19
20 -.~-3.5 -2.1 191 1.0 1.1 058 5.1 [14 -9.8 0.0 485 21
I 21 4.3 -2.1 1.2 128 1.1 1.3 098 6.3 SE 71 -2.4 ...905 21
22 3.1 -3.5 .1 lI4 1.1 1.4 099 5.1 E b2 -9.2 1.0 195 22
23 .9 -8.1 -3.9 110 1.4 1.5 lI3 1.1 ESE 45 -18.4 1.8 378 23
I 24 -1.6 -1D.9 -6.3 121 .8 .9
123 3.8 ESE 47 -15.0 '.0 1207 24
25 -3.3 -12 .5 -1.9 111 1.1 1.3 112 4.4 ESE 12 -IU 0.1 81 8 ::!5
26 -t.6 -9 .2 -5.4 108 1.1 t.s !14 6.3 [59 -1 4.1 0.0 131 tb
I 21 -.2 -28 .4 -14 .3 131 1.1 1.3 093 5.1 ESE 'Sl -6.\0.0 1146 21
28 .1 -4.0 -2.1 121 .1 1.2 105 5.1 SE 53 -12.1 n.o bt4 29
~9 -2.1 -U .O -6.0 111 .8 1.0 011 3.3 [14 -36.8 ...415 29
30 -1.4 -5.2 -3.3 253 .3 .6 2 4~2.5 WSll 22 -2b.7 0.0 m 30
I 31 -3.5 -8 .~-5.9 166 .3 .1 m 3 ,~wsw 1 -35.4 n.1 JD4 :;1
"ONTH 7.1 -28.4 -2.5 112 .8 1.2 012 8.3 fSE 'Sl -14.1 r .n 30578
I GW:;T 'JE t.. AT MAX.GUS T MI NU S 2 n n U~~'A I.s ..,.0"'.....t...
r;U S T \}i ~L .AT MAX .cus r MHI IJ::;1 T.N TERV AL C".,
....1 ••
GUS T \}EL .AT MAX .GUST PI.U B 1 I NTERVAL ~l,.,"\
I Nm E :
GWH VEL .Ar MA X.G U ~1T fl U .1!)2 INT ERVA LS 7,0
~E I .ATIV E HU M]OJTY P F.AD I NGS AR F I.J NRF I.IAfll.E ~!H I-::N I,IT NI>:~P l:~.j)!::AI ~F I I ::-~:S nlo~\rJ
ON ~Mt-:TF::R P f::R !:lI:·x rJNl).SUCH Rf::A DING S HAI }E NIH BI.'F.N I NCL UOl.'])Til I -DAI I..Y
I or~MONT HI ..Y MF.P.N F OR REI.ATT VE HU MTl lTTY AN D IlFl·1 POTNT.
I
I~
('.'~
.".?J.
&-1"1
(ifj
CONSULTAN·T"S.INC.
SlJSITNA I-IYDROELECTR :[C PI~OJECT
MONTHL Y SU MMA RY FOR WATAN A WEAT HER STATION
DATA TA KEN DUR ING Se p teMOer .1983
RES .RES .AUG.~JU.IIAX .DAY 'S
IIAX .IIIN.lIEAIt WINIl WIND WIND GUST GUST P''JAl IlEAH ~.EAN SOLAR
DAY TEIlP •TEJlP .TEIlP •DIR.SPD.SPD.m.SPD.DIR.RH DP PRECIP ENE.~CY DAY
~C C DEC C DEC C DEC illS illS DEC illS I D"C C M IliIISQII
I n ...I''''H'"II'IH.n .....I'"III H ........,IIIIH I
2 "IH IHH .....IH H".H.IH ....IH H .....U 7&69 2
1 &.1 1.4 1.8 078 1.8 2.0 048 5.1 E 55 -5.1 1.0 2755 1
4 10 .1 4.4 7.2 143 2.2 2.9 195 &.1 NNE SO -3,3 1.0 7428 4
5 'HH .....I ...........I'".......I"I'I ....III'......5
&"H'...n t .......t ...t ...n.tHI II'n n •••I'"t .....&
7 a.3 2.3 5.1 089 1.3 1.7 2&6 Q.3 E 8Z 2.7 2.a no 7
a 3.4 3.2 3.3 118 1.2 1.2 024 1.9 NNE 99 3.1 ....240 a
9 a.8 u ~.2 2BQ I.Z .loS 2ao &.1 W 74 2.6 \.0 2421 9
10 11.0 4.2 7.&Z9Z \.3 2.1 252 5.1 N &9 1.9 0.0 4151 10
\I 11.1 1.&&.4 la4 I.Z 1.&093 4.4 E 71 .9 \.0 18 14 \I
12 II.Z 2.&&.9 283 .5 1.&293 5.7 NNE b7 .9 0.0 3123 12
13 8.1 1.2 4.8 081 U 1.9 089 9.5 E &7 -1.5 0.0 1981 13
14 5.2 .1 2.7 03&.b 2.7 091 5.7 EII E 70 -&.2 1.2 1m 14
15 7.~.1 1.9 015 .&1.5 257 4.4 N 4&-11.9 0.0 2b&a IS
1&10.7 -3.2 3.8 0&&1.3 1.8 12&&.1 NNE &2 -2.4 0.0 4123 1&
17 10.1 -4,7 2.7 305 .9.2.1 243 &.1 HItE &7 -3.1 2.0 4414 17
18 B.&-&.7 I.G m 2.5 2.9 083 44.B E &4 -u '.0 2403 19
19 7.2 U 4.4 oal 4.8 4.9 093 10 .2 E sa--&.0 1.8 1851 19
20 a.s 2.7 5.&0&&2.1 3.0 195 8.3 EIIE 41 -14 .9 1.2 1975 20
21 a.l 4.5 ~.4 094 1.1 1.4 083 5.7 ESE 27 -20 .0 U 1943 21
Z2 t ....i ......-tttl ift if"if..if.I'"t ..n lit..lilt 111'11 22
23 I ....t ....ntll I"I'"1.11 n.I.tt .n H Ittll ""III'"23
24 I""tt'"...tt ttl tHI n ..t"tt..t ••t."'11 I'"II....24
ZS tlill tI..t t ••"ttl ....n ....t "II til ..nt..H"IttHI 25
2&IHtl .....HH1I Itt ....I'"...ttt.t ....illft t ...tftlH 2&
27 11111 111ft "'it Itt ....Ht....lI.t III H III""II u ...t 27
28 ...tt 1..1t tHIl HI Htt I'"I"ill I II'..11114 Iftt Htl.1 29
29 .1•••IItlt flJlI lit 1111 1111 ttt 1111 ttl II u ....II...UtHt 29
30 f,ltt ttttf I t t l .ttt IItt Itt.ttt Itlt Itt II fI 't.Htt uttll 30
IIfJH Tri u.a -u U Q ~1.4 2.5 083 44.0 ..&1 -u 11.0 53997
GUST VF.L .;,T M ~\;(•GU S T MI NU S 2 IN TE RV ALS 2 .5
GUS T Vt:L.AT MA X.GUS T MI NUS 1 I NT F::RVAL 4.4
GUST '/EL .
AT MAX.GUST P LU S I ItlT ER'JAI 1 .9
GuS T VF.L .AT MA X.GUST PLUS 2 INTE:RVAL S 1.9
I ~O T F.':RE I..ATJ 'JE HU MI DITY REA DIN G::>AR E UNR ELIA BLE WHEN WI ND SP EED S fll~E LESS THMl IONt:METER flF::R SECG N f,.S UCH RE:A Dt NG S HAVF:NOT BEF::rI I NCLUDE!)H i THE DAIL Y \~OR MONTHI .Y i1F AN F OI~I~ELA TI IJF.HUMI DITY AND DEW PO I NT.
.~•.)(o;*.f:S E:E NOTES AT THE:BAC K OF THIS RF:PO RT .x,.x,x,·x·
I r c.-.
I~~,.M C O NSUL T A NTS __:t:NC .
I S l.J~:;:I :TN A H Y 1)I~D E I...t:::C T I ~:I:C PI~o :r E C T
I MONTH LY SUMMAR Y FOR WAT AN A WEAT HER STATI ON
DA TA TAKEN DUR I NG Oct o ber ..1983
I RES.RES.AVG.IIAX .IIAX.DAY'S
I
W ."IN ."EAN lIND lINt 11111I CUST MT P·VAl.IlEMf !IAN SQ.AR
DAY TEIP.TBIP .TEIlP •DIR .SPO .SPO .OIR.SPO .DIR .RH Ill'PRECIP ENEReY OAY
DEG C DECC DECC DEC "IS "IS DEC illS %DEC C III lIH1SO"
I \IUH .HH _....._
""-HH 'H H -HH _HI \
2 _H HH.1_'H'HH 1-.H IH'H'H .-HH .-2
3 H ' H
H_H H '
,H HII
_-HH -H tH..HH H,HI 3
I ~_H HIH .-IU .H.HM 'H 1-.H H HH.HII -~
5 _H IUH HIH 'H IU.-IU IH."'U HIH •HI ."H•5
b H'H HIH .HII IH -.tH IU IIU IU H IUH HH .-b
7 H'H
_.I ....H'-.-H'"""'H ..-IIH IUtH 7
I 8 "'"UtH "--IH.HM tH I'"-H ---8
9 ."H IHH un.IU .IU ,H,IU un IH n lUll ..0 H ....9
II .."I tHft '''H ...H ..--tH..H U
_.
tH.HUH 10
I 1\.-flUl 'H"IH UH .HI 'H HH 'H H IlIU .HI IH,"1\
12 UHI IHH IUH IH IH.UH H'.-'"H _0 IIH .H_\2
\3 HIH ._.HIH IU .IU
__.-IU H UH.Hli
_...13
I 1~UH.,HH HH.'H HH Hft H'IIH IU H tHH HH -H
15 HIH
_.
HH..H
_.-IU
1_
'H H .-HH HHII 15
Ib HfH HIH
_.-HH .fH H'.IU -H H_lUI HHH Ib
I \7 .9 -.8 .\171 1.1 1.1 187 b.3 EI£81 -2.2 1.1 lI b~17
18 .5 -5.I -2 .3 Obb 2.7 2.7 07~7.b EI£75 -5.b 1.0 \510 \8
19 -2.7 -6.3 .....5 Obi 2.~2.b 059 b.3 EJ(71 -8.8 1.1 S75 19
20 -2.7 -5 .2 .....1 Ib9 4.7 ~.8 lSI 9.5 ENE 77 -7.b .2 Hl5 20
I 21 1.8 -3.2 -.7 Ob7 3.8 4.1 195 9.5 ENE b7 -6.4 1.1 11 41 21
22 -.\-4,6 -2.4 lbe 3.\3.2 Dbb 9.5 EJ£b9 -7.3 .4 1291 22
2J -1.9 -7.\-4,5 164 3.\3.4 185 11.2 EllE 75 -8.6 1.1 1431 23
I 2~-2.4 -U .5 -b.5 17b I.b 2.1 115 5.7 E ss -\2.8 D.D 13bl 24
25 -b.7 -9.4 -8.\15D 4.9 4.9 057 8.9 HE 51 -\b.5 1.1 1495 25
2b -4.b -9 .\-b.9 172 4.5 5.1 058 \4.D EllE 71 -\1.9 .8 1\81 2b
I 2J -2.7 -1\.8 -7.3 162 2.9 3.\D57 b.3 NE be -11.b 1.1 975 27
28 -2.9 -8 .3 -5.b 180 3.2 3.b D84 \1.4 ENE 77 -7.8 .8 781 28
29 -1.3 -9,6 -5.5 Ib9 2.5 2.b D79 8.3 ENE 85 -b.5 1.1 bJD 29
3D -2.3 -&.I -4.2 295 1.1 1.5 294 ~.4 IIHII 91 -6.4 .8 82S 31
I 31 -3.b -\1.9 -7.8 175 .8 3.4 182 11 .8 E 81 -s.s 1.1 470 31
1l0llTH 1.8 -\1.9 -4.7 Ibb 2.8 3.2 058 \4.1 EJ£73 -8.5 J.D Ib529
I GUST VEL.AT MAX.GUST MI NUS 2 I NTERVALS 8 .9
GUST VEL.AT MAX .GU BT MINUS 1 I NTER VA L 1 3 .3
GUS T VEL.AT MAX. GUST P LUS 1 IN TER VA L 1 0 .2
I GUST 'J EL.AT MAX .GUST PLUS 2 I NTERV ALS 1 1 .4
NOTE :RELATIVE SPF.E DSHUMIDITYREAJ)INGS ARE UNRELI ABLE WH EN WIND AR E LESS THAN
I ONE METER PER SECOND .SUCH READINGS HAV E NOT BF.EN I NCLUI>!::l>I N THE DA I LY
OR MONTHLY MEAN FOR RELATIVE HUM IDITY AND DEW POINT .
****SEE NO TES AT THE BACK OF THIS REPORT 1(-***
I
I~
SUSITNA ~IYDROELECTRIC PROJ ECT
MON THL Y S UMMARY FOR WATA NA WEATH ER STATION
DAT A TA KEN DURI NG NoveMb e r.1 983
RE S.RES.AIJG.!lAX.1lAX.DAY'S
"AX."IH.IlEA H WIND WIHD WIND GUST GUST P'VAL IlEAH J'iEAH SOLA R
DA Y TEllP •TEill'•TEll!'•DIR.S1'D .S1'D.DIR .SPD .DIR.RH DP PREC IP EllER GY DAY
DEGC DEC C DEGe DtC IV S IV S DEC IV S %DEC C IIIl IlH/Sg"
I -2.3 -13.4 -7,9 108 3.9 U 184 8.9 ENE 69 -11.9 0.1 745 \
2 -\.8 .-\1.2 -/1,1 165 5.\5.4 157 11.4 EltE 08 -9.9 1.1 555 2
3 -1.8 -18.Il -6.2 167 2.1 2.3 151 5.7 E 72 -11.2 0.1 1445 3
4 -3.3 -!I.9 -7 .6 164 3.9 4.1 180 8.3 EltE 61 -13.6 1.0 6\5 4
5 -5.1 -12.I -a,&163 1.4 1.6 114 4.4 E 7G -12 .8 1.0 630 5
6 -1.7 -14 .8 -1\.3 073 2.7 2.9 174 1G.2 EltE 75 -15.0 1.0 11 95 6
7 -6.8 -11.6 -9.2 161 6.5 6.6 056 12.1 EltE 69 -14.3 D.I SIS 7
8 -.2 -7.l -3.b 163 4,7 4.B 061 8.9 EltE 57 -\\.I U 510 8
9 -\.0 -8.4 -4,7 071 6.0 6.0 078 12.1 tIlE 42 -15.4 0.0 eSI 9
IB -4.1 -8.4 -6,3 073 4.9 5.0 084 12.1 EltE 44 -16 .4 1.0 b80 II
\I -2.5 -9.9 -6.2 on 3.3 3.5 076 8.9 EHE 49 -16.1 U 591 \I
12 -b.8 -12 .3 -u 073 \.4 1.6 062 6.3 E 62 -15.8 1.0 361 12
13 -7.1 -15.6 -11.4 08 0 3.1 3.1 176 7.6 E 71 -IS.4 1.0 1001 13
14 -9,2 -15.1 -12 .2 084 3.2 3.3 188 8.3 E 72 -15.9 1.0 941 14
15 -6.6 -16.2 -11.4 o~S.O 5.1 068 9.5 E 65 -15.7 1.0 415 15
16 -u -15 .0 -11 .8 073 2.6 2.7 181 \1.2 ENE 83 -\3 .\.4 597 \6
17 -7.8 -15 .9 -11.9 171 3.1 3.2 066 11 .8 ENE 84 -14 .7 U 395 17
18 -11.2 -18 .\-\4.2 056 1.7 \.9 184 4.4 E 84 -\6.9 8.1 6\5 \8
19 -ID .I -18.1 -14.1 046 1.0 1.3 329 3.8 EltE 87 -16.6 1.0 525 19
20 -6.7 -18.5 -\2 .6 m 6.\b.2 175 \2.7 ENE 83 -13.3 U 250 20
21 .9 -6.2 -2.7 184 7.1 7.8 194 14 .6 E 7B -5.1 0.1 241 21
22 -.8 -9,\-S .I 169 2.2 2.3 089 8.3 E 88 -b.4 0.0 355 22
23 ·6.4 -19.6 -8.5 196 2.1 2.0 09S 5.\E 88 -10.0 U 281 23
24 -7.5 -\4.5 -11.8 078 3.4 3.6 066 7.1 E 81 -13 .7 U 530 24
25 -II .0 -14.5 -12.8 863 4.6 4.7 .76 9.S EHE 83 -15.0 0.0 480 25
26 -7.5 -11.7 -9.6 16 8 4.7 4.B 159 8.3 EltE 74 -13.0 U 33S 26
27 -5.\-u -7.4 062 3.4 3.S ISS 7.6 EItE 82 -9 .8 U 225 27
28 .8 -boa -3.0 m 6.7 6.8 O~14.0 ENE 78 -&.6 0.0 288 28
29 \.8 -I.~.1 072 U 6.2 095 13.3 ~1tE 57 -7.2 0.0 29S 29
31 •-2.5 -l.O m 5.\5.3 883 \2.\ENE 55 -9.1 1.0 315 30."
nliHT H 1.6 -1&.5 -ij .2 071 3.9 4.0 094 14.6 tilE 71 -12.7 .4 10792
GU ST 1...'i L,AT MAX.GUS T MI NUS 2 IN TER'JALS 1 3 .3
GU ST VF::L .AT MAX.GU ST MINUS 1 INTE:RVAL 1 3 .3
GUS T VEL.AT MAX .GUST P LUS 1 IN TERV AL 1 4 .0
GUST VE:I...AT MAX.GUST PLUS 2 I NTF::RVALS 1 3 . 3
:,OTi:':RE'L AT J'JF.HUMIDITY Rt=:ADJrJGS ARE UNRE LIABLE WHEN WI ND SP EED S A I ~E LESS ,HA ,'!
ONE ME:T F::R PF::R SE:CON D.SUCh READ INGS HAVE:NOT BE F.:N I NCLUDED IN TH E DAILY ~I
Of(MO NT :"1 1..1 ME AN t=OR RELATI'.'F.hUM I DITY AND DEW POI NT .
k lt 'k '""SF::E NOT ES AT THE BACK OF THIS RF::PORT ·It·X··>t,·x·
I (j (i~
,~/f;M f'"'Cl N c-,l J 'TAN T c·~:;.?:t:NC••JO ....:).•• •••...:)...
I S U S:J:T N A
HYI)'~Cl E L E CT,~:t :C p I ~Cl .r E C T
I MO NTH LY SUMMARY FOR WATAN A ~.IE ATH ER STATI ON
DA TA TAK EN DURI NG Dec e Mb er ..1983
I
IES.IES .IWC .IIAX.IIAX.DAY 'S
IIAX.HIH.IlEAIl WIND WIND WIND CUST CUST P'VAl ~EAIl H£AN stlAIl
I DAY TEIlP •rutP .TEI1P •011.SPO.SPO.DII.SPO .DII .IH DP PRECIP EIDCT DAY
OEC C DEC C DEC C DEC HIS HIS DEC HIS %DEC C ""WHlSIlll
I 1 .3 -4.2 -2.0 170 4.0 4.2 IS4 8.3 ENE 1>8 -6.8 0.1 231 1
2 -2.4 -~.3 -4.4 038 .7 1.3 151 4.4 E 91 -6.0 1.1 rn 2
3 -6.1 -11 .6 -8.4 085 1.1 1.3 118 3.8 E 9Q -9.8 1.1 321 ,
"
I 4 -7.0 -8,6 -7.8 074 3.2 3.3 079 9.5 ENE 90 -9.0 1.0 141 4
5 -3.9
-7.9 -5.9 01>8 1.6 1.7 055 4.4 E 9Q -6.8 ...141 5
6 -4,2 -6,4 -5.3 oea 2.1 2.2 178 8.3 E 91 -6.7 0.0 205 6
7 -5.1 -8.7 -6.9 178 5.3 5.3 178 9.5 ENE 37 -8.1 0.0 JJ5 7
I 8 -8.6 -14 .5 -11.6 076 5.0 5.1 192 10.8 ENE 85 -13 .8 1.0 J85 8
9 -13 .6 -20 .2 -1 6.9 082 6.5 6.5 077 11.4 E 65 -23 .1 0.1 345 9
11 -13.7 -19 .2 -16.5 069 7.7 7.7 169 12 .1 ENE 65 -21.8 1.0 245 10
I II -11 .3 -15.2 -12.8 175 6.3 6.4 177 11.8 ENE 7J -16.6 1.1 215 11
12 -10.4 -15.2 -12.8 083 5.4 5.4 081 11 .8 E 7J -16.1 0.0 1'r.l 12
13 -12 .6 -14.7 -13.7 168 5.8 5.8 165 1D.8 ENE 79 -16.3 1.1 151 13
I 14 -15.3 -22.7 -19.1 176 1.5 1.6 082 3.2 E 84 -21.1 '.P 320 14
IS -17.2 -24 .3 -21.8 066 4.4 4.4 067 .10.2 ENE 79 -22.4 '.1 381 15
16 -18 .4 -21.9 -20 .2 158 2.9 3.3 075 7.1 NNE 77 -23 .2 0.0 221 16
17 -15 .1 -19 .7 -17.4 101 2.4 2.5 069 6.3 ESE 83 -19 .2 1.0 1BI 17
I 18 -9.2 -11>.7 -13 .0 oea 3.0 3.1 083 10 .8 E 85 -15.6 0.0 275 18
19 -8.1 -14.0 -11.0 178 5.5 5.5 181 11.8 EHE 74 -13.9 1.1 191 19
20 -6.3 -1D.2 -8.3 181 2.8 2.9 178 6.3 ENE 76 -11 .5 0.0 181 20
I 21 -5.5 -13 .0 -9.3 162 3.6 3.7 188 7.6 ENE 88 -9,3 U 191 21
22 -12 .6 -16.9 -14.8 080 1.8 1.8 m 3.8 E 89 -15 .9 0.0 341 ~2
2J -13.5 -17.2 -15.4 I7J 1.9 2.1 087 4.4 ENE 88 -16 .7 1.1 37S 23
I 24 -1.7 -17.7 -9.7 099 2.5 2.6 115 8.3 E 84 -14.7 1.1 J75 24
25 -3.6 -13.9 -8.8 091 3.1 3.2 171 5.7 E 72 -13.7 1.1 3S5 25
26 -6.2 -1 3.4 -9 .8 I7J 2.7 2.8 169 6.3 ENE 65 -15.4 0.0 285 26
I 'l7 -7.9 -18.1 -13 .1 083 2.3 2.4 198 5.1 E 7J -19 .1 1.1 271 27
28 -17.1 -22 .7 -19 .9 076 2.5 2.6 176 6.3 ENE 77 -22.2 U 35 1 28
29 -21.0 -22 .7 -21.4 074 2.2 2.2 192 4.4 E 79 -23.9 0.0 361 29
30 -21.4 -26.7 -24 .1 081 1.8 1.9 167 4.4 E 79 -26.4 0.0 345 31
I 31 -11 .9 -22.2 -16 .6 095 2.2 2.3 168 7.1 ESE 82 -19.1 D.I 145 31
IIONTH .3 -26.7 -12 .8 077 3.3 J.S 069 12.1 ENE SO -15.6 0.0 S2'15
I GU ST 'JEt..AT i'I AX.GU S T MINU S 2 I NT ERVA l.S 10.n
GW3T VEL .AT MAX.GU S T MINUS 1 IN TER l.JA L 10 .n
GU ST VEL.AT MA X.GUS T PLU S 1 I NTERV Al...10 .n
I GUST VEL.AT MA X.GUST PLU B 2 I NTE RVALS 1 0 .8
NO TE:RE LATIVE HUMIDITY READ I NG S AI ~E UNR ELI AB LE lm EN
WI ND SPEr DS AR E LESS THAN
ON C MET ER PErl Sf::GONI>.:;UGH READINGS HAVE NOT Be EN I NCLUDED IN f il E DAI I.Y
I or~MON THLY ~I E ~,N F OI~RELATIV E HUM I DITY AND D EI ~P OI NT .
I
L
(,('"",'I~&M CONSULTANTS.:I:N (: .
SUSI "TNA ~IYDI~O ELECTRIC PROJI~CT
MONTHLY SUMMARY FO R DENALI WEATH ER STATION
DAT A TAKF.:N DURI NG SePTeMber ..1 983
ilES.RES.A'JI;.IIAX.1lAX.DAY 'S
"AX."IN .Il£AH 'lliHIl IIIND 1100 CUST GUST ?'lJAL l'£AH NtA N SOLAR
DAY Ttr.!'•TEIlP •T£!l,O •DIR.SPD .S?D.DII .S?D .DII.RH DP PRECIP EllERey DAY
DEC C DECC nt CC DEC MIS illS DEC "IS %DEC C ""lllIISQII
I I""II'"II'"IH 1111 III'tH ....I"I.IIH..0 IItI..I
2 7.4 -.1 3.7 338 2.5 2.7 ~8.3 NNII SO -5.'.2 4531 2
3 9.4 -.0 4.4 173 1.5 2.2 102 7.'S 52 -5.9 O.•3922 3
4 5.3 .4 2.9 ...0.'1.0 tI.0.'.H H .....'.0 3990 4
5 5.4 -1.5 2.0 .......I ..'tH .......47 -ta .1 Q.i 3324 5
0 b.b -.9 2.9 •••.... ....I"II"-53 -7,5 0.0 4801 &
7 8.0 -.9 3.&I"........tI.1..1 ...52 -7.1 0.0 2&85 7
8 7.0 \.1 4.4 ....... .....It ....I"49 -9.1 .4 2410 8
9 9.3 2.0 U I..I'"....II'....I"59 -5.4 0 m &9.~
10 10.0 .1 5.1 ...lit...............52 -8.5 0.0 3225 10
11 10.3 -2.5 3.9 .H 1.1t .........II I ..58 -b,3 o••27&8 11
12 u.i 2.4 &.3 .11 "11 ....III .......40 -8.0 0.0 1984 12
13 U .I 4.1 II.........I'•"II '"49 -8.7 0.0 221&13
14 1.4 .&4.0 ...'.H.....-till -5&-7.7 i .a 1552 14
IS U -2,5 U ...II".H....I ...I ..55 -10 .7 0.0 3503 15
1&8.0 -2.'3.0 -1111
_........"'43 -13.1 U 4070 1&
17 9.4 -4.5 2.S I ..II "............If 55 -7.8 U 4047 17
18 7.9 -5 .2 1.4 ...0.0 ...n •0.0 .n II '""U 3130 18
19 &.8 .1 3.5 I ..""""I"""III 52 -10 .0 0 1859 19.~
20 9.3 .7 5.0 "'11 11 ""'"I'"III n -2.5 5.2 12&&20
21 7.3 3.3 5.3 I"........I"....I..59 -u .8 1098 21
22 5.2 -4.4 .4 I"""111I ....11.I "47 -9.0 1.4 124&"..
23 -4.8 -8.2 "'~.5 I"1111 1-"'....III 57 -15 .7 0.8 233&23
24 -7.&-ID .O -8.9 .......111I '"....-&7 -14 .8 1.0 197 1 24
25 -5.8 -12.7 -6.9 tI.....I'"...I ' "
'-it 52 -18.4 0.0 3203 25 I2&-5.5 -17.1 -I U ...•11...............50 ..21.2 U 3327 2&
27 -3,7 -15 .7 -9,7 I II ....H II ...""I II 57 -17 .4 0.0 2773 27
28 .7 -4.a -?.1 •••"II I'"..."II "I 60 -9,8 0.0 131 5 28
29 .7 -408 -2.1 n.nt.JI.I ...lilt U.&0 -9.8 0.8 1315 29
30 7.3 3.3 5.3 ............It .......59 -5.9 La 12 49 30
~u ~T ~10.3 -17.1 1.1 W .1 .9 -re-e 8.3 S 55 -9,7 11.2 7i J1 52~""
GlJ ST VF.L.AT MAX .GUST MINUS 2 I NTERVAl S 9 99 .0
GU ST IJt:l_•AT MAX .GUST rl1:NUS 1 I NTERV AL 9 99 .0
GUST VEL.AT MAX.GUST PLUS I I NTER l)AL 6 .3
GUS T VF.:L .AT MA X.GUS T P I.US ~I NTERVALS 7 .0,-
NOT!C :RF.Lf'tTIVF.:HUMI DITY READINGS ARE UNRELIAB LE WH EN WIN D S PEEDS A I~E LESS THAi'H
O NF.:i":F.:TF.R PI".R S SCO;-'If) .S UC H RF.ADII'I GS HAVF.:NOT t.EF.N I NCLUDE D lf~TI"IE fJA i l..(
OR MON THL.Y MFAN FOR RE LAiI'JF HUMIDIT Y AND DEW P OH 'i,
i':.x-.x-·x·S EF.NDT F.:S AT THE B ACI(OF TH IS RF.:POR T .)t"~.~,,,
(I (-.'
..~..}
I~~M C C)N SUI...TAN T S .:I: N C
I S U ~:>:t:TNA H Y J)I~C)EI...ECTI~:J:C p I~C).T ECT
I MONTHLY S U M ~I A RY FOR I>F.:N ALI WE ATHE R STATI ON
DA TA TAI<F.::N DURI NG NO\le Mb er ,1 983
I RE S.RES.AVG .IlAX ./lAX .DAT 'S
/lAX .HIN .Il£AIl WIND WIND WIND I;UST I;UST P'VAL ItEM MEAN Wi
I OAT TEW .TEMP .TEMP .DU .SPD .SPD .DIR.SPD.DU.RH or PRECIP ENERGT OA T
DEC C DEC C DEC C DEC HIS HIS DEC HIS %DEC C ""WHlSlllI
I I -0.0 -13.0 -9.5 :H2 1.2 2.1 172 7.6 N II 11111 '.1 rn I
2 -2.4 -12 .7 -7.6 182 2.7 3.7 176 14.0 S II H ...0.0 60S 2
3 -7.5 -19.4 -13.5 :H2 .9 1.2 339 3.2 N H .IIH 1.1 1361 3
I 4 -11.7 -21 .5 -16 .1 3S2 .9 1.2 117 3.8 N II IHII 1.0 761 4
5 -9.5 -17 .2 -13 .4 3.."7 .4 1.1 167 4.4 NNII II IIHI '.1 645 5
6 -13.4 -20.8 -17 .1 3S5 .3 .8 309 5.7 NNE II HIH 0.'1020 6
7 -bob -14.9 -10.8 193 5.7 5.9 181 11.4 S H .....'.1 561 ~.
I 8 -2.1 -11.9 -7.1 214 1.1 2.3 209 7.6 SSW II IHH 0.0 640 a
9 -3.8 -14 .4 -9.1 195 t.S 2.9 197 IU ssw H IIIH 0.1 985 9
10 -b.S -16.8 -11 .8 027 .2 1.7 ISS 8.3 ~II IIIH 1.0 710 10
I II -8.1 -15.7 -II.9 173 1.2 2.8 173 11 .8 N H IHII 1.1 93S 11
12 -8.2 -16.0 -12.1 182 .2 1.1 182 8.3 SSW II IHH 1.8 540 12
13 -12.0 -20.5 -16.3 .122 .1 .6 827 1.9 S II .....1.1 10SS 13
I 14 -15 .9 -20.8 -18 .4 029 .8 .8 006 1.9 NNE H .....0.0 568 14
15 -16.8 -24.3 -20 .6 360 .2 .6 278 2.5 N II 111II 0.1 475 15
16 -9.4 -19 .4 -14.4 144 .3 1.3 153 8.9 NNE 29 -22 .7 0.8 725 16
17 -17.8 -2\.?-19 .9 347 .5 .9 DOD 3.2 N 25 -35.3 0.1 48S 17
I 18 -14.7 -21.2 -18.0 009 .8 .8 006 2.5 N 36 -30.7 1.0 7SS 18
19 -7.8 -22.1 -14.9 295 .1 .9 149 2.5 SSW 47 -24,8 1.1 391 19
20 -3.5 -16.9 -ID .2 169 5.4 5.8 143 17 .1 S 4b -23.7 0.0 :ISS 20
I 21 2.6 -2.0 -.1 151 6.9 7.3 152 2:'.2 S£b1 -9.8 1.1 3S5 21
22 -1.1 -11.6 -6.4 183 2.9 3.3 m 11 .8 S 47 -17.5 0.0 4tD 22
23 -5.1 -16.1 -11 .5 114 2.2 2.4 3S7 7.1 NNE 36 -22 .9 1.1 621 23
I 24 -8.5 -21.8 -15 .2 DOl .8 1.7 121 6.3 NNE 3S -27.7 1.1 7SS 24
25 -1 2.1 -17 .7 -14.9 171 2.3 .3.t 175 10.2 S 76 -16 .9 1.1 505 25
26 -11 .8 -18 .3 -15 .1 33 9 .3 1.1 181 3.8 NNE 65 -20 .3 G.D 425 26
27 -7.6 -16.1 -11.9 21l'I .3 1.6 188 6.3 N b2 -21.2 U 331 '2JI284.2 -1D.b -3.2 152 6.5 6.9 154 21.6 S£52 -1 1.&U 375 28
29 5.0 -2.1 1.5 177 ~~2.8 14~14.6 SSW 50 -~.7 U 3S5 :!9...
30 .1 -5.3 -2,2 193 1.7 2.4 182 11.4.S 54 -11.4 U 480 31
I ItOHrH 5.0 -24.J -11.7 171 t.O 2.4 152 .,."N ~1 -21.2 0.1 18a65i,.&",,-
GU ST VEL .AT MAX.GUS T MI Nt :S 2 JNTF.RV ALS 2 1 .0
I GUS T '.)[1...AT MAX,GUST MI NUS 1 I NTERVAl.15.'I
GUST 'JEl..AT MAX .GUS T PLU S 1 I NT FR~!AI..15 .2
GUST ll EI..AT MAX .GUS r P LUS 2 I NTERvALS 15 .9
I NOT F.:RELATIVE HU MJ IlITY READJNr,S ARE"UNRELIABl.E I·!H~:N I.IT NIl SP F.:F n s Ar~F I.E SS TH AN
ONE MET F:R Pr::R s eCOND.!i UCH READ INGG HA\.Jf '.Nor BE F.N I N I ~L..U n I.':O I N T"HE DAI ,_Y
O l~MO NTH LY MEMJ FOI~RELATIVE HUMJD JTY AND )l EI.'pn INT.
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CONSULTANTS.:J:NC .
SUS :J:TN A H Y D I ~DEI...E C T I~:I:C P l~Cl .T E C T
MONTHLY SUM~IARY FOR nENALI ~!F.:ATHER STATION
DA TA TAK EN DURING De,=I?Mb er-.'1983
tES.tE S.AIJC./lAX.HAX .flAY'S
HAX."IN .ItEAII \l IND \lIND \lIND GUST CIJST P'VAl.MEAN lEAH SOlAR
DAY TEIlP •TEIIP .TEIIP •DIR .SPD.SPD.DIR.SPD .DIR.RH DP PRECIP ENERGY DAY
DEC C DEC C DEC C DEC MIS "IS DEC MIS %DEC C I1ll WHiSOlt
1 -.8 -4,9 -2.9 179 .9 \.S 189 7.0 S 5~-12.7 1.1 355 1
2 -2.'-7.S .....8 170 1.3 1.6 163 S.7 SS E 47 -1 ~.4 U 340 2
3 -3.1 -11.7 -7.~219 .S \.8 189 3.8 SSII 37 -20.7 U m 3
~-6.2 -10 .8 -a.S 117 3.7 4.1 183 10 .8 5 23 -2U 0.0 281 ~
S -5.4 -9.3 -7.~117 1.1 I.S 176 6.3 S 'll -22.8 '.1 281 S
6 -6.5 -7,D .-6.8 268 .~.7 303 1.9 IlHII If Iflfl 0.0 120 6
7 -5.3 -7.1 -6.2 IS3 .7 t.3 174 9.5 SSII 31 -21.2 O.I m 7
8 -5.4 -12.6 -9.0 165 2.0 3.1 I7Z 8.9 S 38 -23 .3 U 315 8
9 -12 .5 -14.0 -1 3.3 m .9 .9 34-1 1.9 NNII 7 -41.2 '.1 2~'9
10 -I~.~-17 .2 -IS.8 009 .7 .7 no 8.9 II 21 Hili 0.0 640 10
1\-16 .6 -16.6 -16.6 0~7 2.0 2.1 052 6.3 NNE «11111 t.O 72.1I
12 lUll 11111 11111 IH IIH 1111 III 1111 HI H Ilffl HH IIHII 12
13 HIH 11111 .....III IIff IIH Iff IIff III II 11111 1111 H IIII 13
1~Iliff .....1IH1 HI IIff HH Iff IIH HI II Iffll IHI 1111I1 14
IS IIIH IHII 11111 HI IHI 11I1 IH 111I III II 1111I 1111 HUll lS
16 HIH IHII .....HI 1111 IIH III HII HI II 11I11 IHI 111111 16
17 Hili 11111 11I11 III HH 1111 Iff 1111 III H 11111 Hli HIIII 17
18 Iffll 11111 11I11 III IIH 11I1 III IHI III II 11I11 1111 fl ~II"18
19 HIff HIH .....IH HH IIff III IIff III H IHII Iffl IfllIl 19
20 11111 11111 Iliff IH HH IH."'IIH IH II 11111 1111 111111 20
21 IIIH 11111 IHH IH 1111 1111 HI IIH H'II IIIH 1111 111111 21
22 11111 IIIH 11111 III 1111 1111 HI IIH IH II HIli 1111 111111 22
23 HH.H'"IIIH III IIff 1111 IH 111I III II 111I1 IHI HIIII 23
2~IIHI 11111 IIHI IH 1111 III'IH 111I III II 1'111 1111 111111 2(I2S11111 11111 11I11 III 1111 1111 III 1111 III II 11111 ......*I..2S
26 'IIH I IHII HIli III IHI IIff II.1111 III II Hili HII 111111 26
27 11111 IHII 11111 III 111I IHI II.1111 IH II 11111 I H I HIHI .,.,."28 11111 11111
Hili III 1111 HII III IHI HI II 11111 1111 111111 29 I29lUll1111111111IH1111IIHIH1111IIIIIifill111111111129
30 11111 11111 IIIH III 1111 1111 III 1111 II'II 11111 1111 111111 3n
31 11111 11111 11111 III 1111 III'III IIH III II 11111 1111 HIIII :1I IIUlNTH-.8 -17 .2 -9.0 174 1.3 1.9 183 10 .8 S 36 -22 .8 0.0 38SS
Gm;T VEL .AT MAX.GUST MINUS 2 INT ERVA I.S (7.5 IGIJSTVr::L.AT MAX.GUST MINUS 1 INTER '.J AL 9 .5
GU ST VE L.AT MAX.GUST PLU S 1 I NTF.:RVAL 9 .~.j
GUS T VI'L .AT MAX .GUS T P I.IJS 2 INTERVA LS 9 . 5
NOT F.:RE LATIV E HUM IDITY IH::AD INGS AR E UNR ELIABLE WH F.N lH NI)S P F.E D~~AR F.I..ESn T.IN
ON E METER P ER S I ::CONO.SUCH REAOW GS IIA \J F.NOT f.iE I~N t NGLUllf.'j)III f HE DA II ..V
Ol~MONT HLY MEAN FDR RELATIVE HIHIIDITY AND DF.:!.!POI NT.
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APPENDIX B
BLUELINE PRIN T S OF AERIAL PHOTO -MOSA ICS
OF SUSITNA R IVER FROM COOK IN L ET TO TALKEETNA
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ALASKA POWER AUTHORITY
SUSrTN A HYDROELECTJUC PROJECT
LOWER SUSlTNA RIVER
~n:Of ....OTOG.~!iV T Il ,ltns:w :".lOa)'~T :r Of"r .
QU t .Z -1 ·'~-_.......
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lOW ER SUSITNA RIVER
:loITl Ol ""'O'"C{,· &"""51·':.:~)•Of 21
5C.OL ("":lCll 0.0.'"1:Z-f-'.
--F~L------
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lL ~_____L..:..:..:_____l
lOWER Sl.ISl'TM.A fWER
o.oTt Ot'~'S[".,••..a 4
:tCAU :IO·ZOOO·tt€n :•M .
0101'1 :I -f ·' .
~1.U1I.1IUU----...!-'!'I ~.~..t
._-~~~...-~
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~~l..-r..t.~ZJ·'1l2:~--:::-.__.....-".""-,,,.,,,,,,
ALASKA POWER A un:~~~
SUSrTNA HYOROEI.fClllIC
L OWER SUSITN A RIVER
~y!Of PM.:)TOG~.P""SE"T ~~~3 •or 11
So;£...l r-ecco llo<U :.7-'.
II ----~-
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----...--..---------------.---.-----------------
ALA SKA POWER AlITHORfTY
.ilISlTNA HYDROa..£CTRIC PRO.ECT
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ALASKA POWER AlJl}iORrTY
SUSITNA HYOAOELECTRIC PROJECT
LOWER SUSlTNA RIV£R
esrr ~"""OlOGQU·,,.SEPT ",191 \3se....t I"'20«1 "5>otET ,0'11
DAl[2·7 -U
ALASKA POWER A~
SUSlTNA HYDA ~CTRIC PflO.ECT
LOWER SUSlTNA~l't OT -aT RtV£A
su,;.r ,'.:&JOMY 51"...IM]S><l£T 10 0""
1:-- - - - - - --,:
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:~------
WER AlJTHQR lTYALASKA PO ELfCTRtC PROJECTSUSrTNAHYDRO
AlASKA POWER AUTHORITY
SUSfTNA HYDROELE CTRIC PROJECT
LOWER SU SlTNA RIVER
:lIoTt Of -..o':x.-..~Sf"".IM)
SU;.I '",200)'50><£[1 ."or n
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lOWER SUSlTNA RfV£R
ALA SKA PO\'VER Al1l'HORfT'f
Sl1SfTNA HYDROELECTRIC PRo..ECl
tlo'T(0'...:;I1 oc;........5("...".,
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SUSlTNA HYDROElECTRIC PflOJECT
LOW£A SUSlTHA.RfV£R
OIoTt 1JIf....".~SPT ...a"
S'-';.l .".lOCI)'S>ClT :••CW II
0101'1.'·T-"
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ALASKA POWER AUTHORITY
SUSITNA HYDROElECTRIC PROJECT
L OWER SUSlTN oI,RIVER
l)I.T[0#hoOT~Sl"" ....]
SUI..(IOo Z'OOO°WI T ~01'"
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LOWER SUSITNA RIVER
ALAS KA POWER AUTHO RITY
SUSfTNA HYOROEUCTRJC PROJECT
OoIoT[01'....D T OG ~..~T SlPT ".IM'
SC""-E,1"'l :Y.lO'~[T :"or II
Dl.Tt :2_1_'.
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Dill r:JI "'oOT~:''''''$I"".....)
5CAl.l r-,loaf w n ."OF PI
out .l -T-••
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SUSITHA HYDROELECTRIC PROJEC l
LOWD:~RIVER
~n 0'PMOTO'~_Sf"....."')
SCIoo.t :1"'lOOO·MU ·'.Of''''
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ALASKA POWER AtmiORITY
SlJSf1l\IA.HYDROELECTFlIC PROJECT
1;WJ .rn::~----
D&T (or ""'01'O~"""Y _I"T ".IM'
5U<.l ,"olOOO P<[':'10 Of'U
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SUSlTNA HYDROELECTRIC PROJECT
LOWER SUSlTNA AfVER
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SCAU '-,2ODO "M tT :II OF n
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SUSfTlol"HYDROE1.ECTRIC PA()..ECT
LOWER SUSO'NA RlY[A
DoLfI 17 ~T O_$I"....Usc.....(,'.lOOO'StClT n Of'U
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DUt Of .~~.....,....,.:u~n CW II
tc.ol.t ,·ZOOO (l,l,T(Z. 1 -14
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susrrNA HYDROEUetRIC PAO.ECT
LOWDI SUS/'TloI A RIVER
llIlT1:'"1'ooCT~$("....,
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AlJTHQRfT'I .AlASKA POWER1lUC PROJEC:"
SUSfTN4 HYDROELEC
t:~l--£:.__._-
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SusrTNA HYDROElECTRIC Pf:lOJECT
LOW EA 5USmlA RrViA
GATt Of ""'OToc.auo.T SlI'"T 16...'
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-::::~--~-
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