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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
SuWa 238
Geomorphology study (Study 6.5), 2014 update of sediment-transport
relationships and a revised sediment balance for the middle and lower
Susitna River segments, technical memorandum
Author(s) – Personal:
Author(s) – Corporate:
Tetra Tech, Inc.
AEA-identified category, if specified:
September 17, 2014 technical memorandum filings
AEA-identified series, if specified:
Series (ARLIS-assigned report number): Existing numbers on document:
Susitna-Watana Hydroelectric Project document number 238
Published by: Date published:
[Anchorage, Alaska : Alaska Energy Authority, 2014] September 2014
Published for: Date or date range of report: Prepared for Alaska Energy Authority
Volume and/or Part numbers:
Final or Draft status, as indicated:
Attachment J
Document type: Pagination:
Technical memorandum 83 p. in various pagings
Related work(s): Pages added/changed by ARLIS:
Cover letter to this report: Susitna-Watana Hydroelectric
Project, FERC Project no. 14241-000; Initial filing of September
2014 technical memoranda. (SuWa 228)
Attachments A-I (SuWa 229 - 237)
Added cover letter
Notes:
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
September 17, 2014
Ms. Kimberly D. Bose
Secretary
Federal Energy Regulatory Commission
888 First Street, N.E.
Washington, D.C. 20426
Re:Susitna-Watana Hydroelectric Project, Project No. 14241-000
Initial Filing of September 2014 Technical Memoranda
Dear Secretary Bose:
By letter dated January 28, 2014, the Federal Energy Regulatory Commission
(Commission or FERC) extended the procedural schedule for the preparation and review
of the Initial Study Report (ISR) for the proposed Susitna-Watana Hydroelectric Project,
FERC Project No. 14241 (Project).1 In particular, the Commission’s January 28 letter
established a deadline of June 3, 2014 for the Alaska Energy Authority (AEA) to file the
ISR, and provided a 120-day period for licensing participants to review the ISR prior to
the ISR meetings, which are scheduled to begin the week of October 13.2 The purpose of
this filing is to provide several technical memoranda to Commission Staff and licensing
participants prior to the ISR meetings.
As required by the Commission’s January 28 letter, AEA filed the ISR with the
Commission on June 3. Among other things, the ISR detailed AEA’s planned work
during the 2014 field season.3 As AEA was preparing this 2014 work plan, it recognized
that data gathered during the 2014 field season, together with other study work conducted
prior to the October 2014 ISR meetings,could assist Commission Staff, AEA, and other
licensing participants in developing the Project’s licensing study program for 2015. For
this reason, the ISR provided for AEA to prepare certain technical memoranda and other
information based on 2014 work.
AEA recognizes that Commission Staff and licensing participants need a
reasonable amount of time prior to the ISR meetings to review this additional
information. AEA and licensing participants consulted with Commission Staff on this
1 Letter from Jeff Wright, Federal Energy Regulatory Commission, to Wayne Dyok, Alaska Energy
Authority, Project No. 14241-000 (issued Jan. 28, 2014)[hereinafter, “January 28 letter”].
2 The full schedule for the ISR meetings appears in Section 1.5 of the ISR, as well as on AEA’s
licensing website, http://www.susitna-watanahydro.org/meetings/.
3 E.g., Initial Study Report §1.3 & Table 3, Project No. 14241-000 (filed June 3, 2014) [hereinafter,
“ISR”].
2
matter, and Staff directed that any additional information should be filed with the
Commission and made available to licensing participants no later than 15 days prior to
the ISR meetings, consistent with the typically applicable deadline under the
Commission’s Integrated Licensing Process regulations.4
With this letter, AEA is filing and distributing the first set of technical
memoranda and other information generated during the 2014 study season, as described
below. As part of its continued implementation of the study plan, AEA expects to file
certain additional technical memoranda prior to October 1, 2014, in accordance with
Commission Staff direction.
This first set of technical memoranda and other information consists of the
following:
Attachment A: Proposal to Eliminate the Chulitna Corridor from Further
Study. As explained in the ISR, throughout the licensing process AEA has
continually evaluated its proposal for Project development based on
environmental review, technical feasibility, practical considerations, and other
factors. As part of this iterative process, AEA notified the Commission and
licensing participants in the ISR that it was evaluating whether to continue
study of the Chulitna Corridor.5 Attachment A details AEA’s conclusion that
development of the Chulitna Corridor is not a reasonable alternative, and
therefore AEA proposes to eliminate the corridor from further study. AEA
seeks any comments or information on this proposal from federal and state
resource agencies and other participants in the licensing process.
Attachment B: Ice Processes in the Susitna River Study (Study 7.6),Detailed
Ice Observations October 2013 –May 2014 Technical Memorandum. The
ISR indicated that AEA would provide a summary of the 2014 break-up
observations.6 This technical memorandum describes all field activities and
observations between October 16, 2013 and May 15, 2014 for the Ice
Processes in the Susitna River Study (Study 7.6).
Attachment C: Study of Fish Distribution and Abundance in the Upper
Susitna River (Study 9.5), Proposed 2015 Modifications to Fish Distribution
and Abundance Study Plan Implementation Technical Memorandum. Based
on AEA’s experience in implementing the study plan for the Study of Fish
Distribution and Abundance in the Upper Susitna River (Study 9.5)during
2014, this technical memorandum proposes to continue certain modifications
to the implementation of this study during 2015.
4 See 18 C.F.R. §5.15(c)(2).
5 See ISR, ISR Overview §1.4.
6 See id., Ice Processes in the Susitna River Study,Study Plan 7.6, Part C §7.2.
3
Attachment D: Study of Fish Distribution and Abundance in the Middle and
Lower Susitna River Study (Study 9.6), 2013-2014 Winter Fish Study
Technical Memorandum. At the time the ISR was filed, AEA was still in the
process of conducting data entry, quality control, and analysis of winter
sampling for this study. AEA reported in the ISR that it would develop plans
for completing this study in a technical memorandum to be filed with the
Commission.7 This technical memorandum fulfills this commitment and sets
forth AEA’s proposal for winter efforts, including proposed methodologies
and modifications.
Attachment E: Characterization and Mapping of Aquatic Habitats (Study
9.9), 2013 and 2014 Aquatic Habitat Mapping Field Season Completion
Progress Technical Memorandum. In the ISR, AEA reported that its 2014
activities for the Characterization and Mapping of Aquatic Habitats Study
(Study 9.9) would consist of various ground-truthing surveys and collection of
habitat information for the 12 lakes within the potential reservoir inundation
zone.8 This technical memorandum reports on these activities.
Attachment F: Eulachon Run Timing, Distribution, and Spawning in the
Susitna River (Study 9.16), 2015 Proposed Eulachon Spawning Habitat Study
Modifications Technical Memorandum.After reviewing the 2013 and 2014
results from the Cook Inlet Beluga Whale Study (Study 9.17) and discussing
the results with the National Marine Fisheries Service, AEA has determined
that additional data are needed regarding eulachon spawning habitats. This
technical memorandum describes a proposed modification to the Study of
Eulachon Run Timing, Distribution and Spawning in the Susitna River (Study
9.16)to include an assessment of eulachon spawning habitats.
Attachment G: Fish and Aquatics Instream Flow Study (Study 8.5),
Evaluation of Relationships between Fish Abundance and Specific
Microhabitat Variables Technical Memorandum. Consistent with the
Commission’s study plan determination,9 this technical memorandum
provides a detailed evaluation of the comparison of fish abundance measures
with specific microhabitat variable measurements where sampling overlaps.
This memorandum is used to determine whether a relationship between a
specific microhabitat variable and fish abundance is evident.
Attachment H: Fish and Aquatics Instream Flow Study (Study 8.5), 2013-
2014 Instream Flow Winter Studies Technical Memorandum.In the ISR,
AEA reported that it would distribute its finding concerning the 2013-2014
7 See id., Study of Fish Distribution and Abundance in the Middle and Lower Susitna River Study,
Study Plan 9.6, Part C §7.1.2.5.
8 See id., Characterization and Mapping of Aquatic Habitats, Study Plan 9.9, Part C § 7.1.
9 See Study Plan Determination on 14 Remaining Studies for the Susitna-Watana Hydroelectric Project,
Appendix B at B-84 to B-86, Project No. 14241-000 (issued Apr. 1, 2013).
4
winter activities in 2014.10 This technical memorandum describes the
methods applied, and data and information collected, as part of the Instream
Flow Study 2013-2014 winter studies.
Attachment I: Geomorphology Study (Study 6.5), Susitna River Historical
Cross Section Comparison (1980s to Current) Technical Memorandum. As
specified in Revised Study Plan Section 6.5.4.1.2.3, this technical
memorandum describes changes within the main and side channels of the
Susitna River by comparing historical survey data from the 1980s with survey
data from the current Project.
Attachment J: Geomorphology Study (Study 6.5), 2014 Update of Sediment-
Transport Relationships and a Revised Sediment Balance for the Middle and
Lower Susitna River Segments Technical Memorandum. The purpose of this
technical memorandum is to update the sediment load rating curves and
preliminary estimates of the overall sediment balance in the Middle and
Lower River segments under pre-Project conditions that were initially
provided in “Development of Sediment-Transport Relationships and an Initial
Sediment Balance for the Middle and Lower Susitna River Segments,” (Tetra
Tech, Inc. 2013a). This update is based on additional data collected by the
U.S. Geological Survey in 2012 and 2013.
AEA appreciates the opportunity to provide this additional information to the
Commission and licensing participants, which it believes will be helpful in determining
the appropriate development of the 2015 study plan as set forth in the ISR. If you have
questions concerning this submission please contact me at wdyok@aidea.org or (907)
771-3955.
Sincerely,
Wayne Dyok
Project Manager
Alaska Energy Authority
Attachments
cc: Distribution List (w/o Attachments)
10 See ISR, Fish and Aquatics Instream Flow Study, Study Plan 8.5, Part C §7.5.2.
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Geomorphology Study (Study 6.5)
2014 Update of Sediment-Transport Relationships
and a Revised Sediment Balance for the
Middle and Lower Susitna River Segments
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
Tetra Tech, Inc.
September 2014
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i September 2014
TABLE OF CONTENTS
Summary .........................................................................................................................................v
1. Introduction ........................................................................................................................1
2. Study Objectives.................................................................................................................2
3. Study Area and Available Data ........................................................................................2
4. Methods ...............................................................................................................................4
4.1. Variations from Study Plan ......................................................................................4
4.2. Sediment Load Rating Curves .................................................................................4
4.3. Bias Correction and Annual Load Estimates ...........................................................5
5. Results .................................................................................................................................6
6. Discussion............................................................................................................................7
7. References .........................................................................................................................10
8. Tables ................................................................................................................................12
9. Figures ...............................................................................................................................19
LIST OF TABLES
Table 3.0-1. List of streamflow gages. ........................................................................................ 13
Table 3.0-2. Sediment-transport data summary. .......................................................................... 14
Table 4.1-1. Summary of sediment load relationships used for the analysis. .............................. 15
Table 6.0-1. 1984 sediment transport measurements at Portage Creek and Indian River (Knott et
al. 1986). ............................................................................................................................... 16
Table 6.0-2. Comparison of average annual sediment loads under pre-Project conditions. ........ 17
Table 6.0-3. Comparison of sediment concentration under pre-Project conditions. ................... 18
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii September 2014
LIST OF FIGURES
Figure 3.0-1. Susitna River study area and large-scale river segments ....................................... 20
Figure 5.1-1. Estimated annual silt/clay, sand and gravel loads at the Gold Creek (Gage No.
15292000)/, Susitna River near Talkeetna (Gage No. 15292100) gage over the 61-year
period of flows under pre-Project conditions. Also shown is the annual flow volume for
each of the years .................................................................................................................... 21
Figure 5.1-2. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Sunshine
(Gage No. 15292780) gage over the 61-year period of flows under pre-Project
conditions. Also shown is the annual flow volume for each of the years. ........................... 22
Figure 5.1-3. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Susitna
Station (Gage No. 15294350) gage over the 61-year period of flows under pre-Project
conditions. Also shown is the annual flow volume for each of the years. ........................... 23
Figure 5.1-4. Estimated annual silt/clay, sand and gravel loads at the Chulitna River near
Talkeetna (Gage No. 15292400), Chulitna River below Canyon near Talkeetna (Gage No.
15292410) gage over the 61-year period of flows under pre-Project conditions. Also shown
is the annual flow volume for each of the years. .................................................................. 24
Figure 5.1-5. Estimated annual silt/clay, sand and gravel loads at the Talkeetna River near
Talkeetna (Gage No. 15292700) gage over the 61-year period of flows under pre-Project
conditions. Also shown is the annual flow volume for each of the years. ........................... 25
Figure 5.1-6. Estimated annual silt/clay, sand and gravel loads at the Yentna River near Susitna
Station (Gage No. 15294345) gage over the 61-year period of flows under pre-Project
conditions. Also shown is the annual flow volume for each of the years. ........................... 26
Figure 5.1-7. Average annual silt/clay, sand and gravel loads under pre-Project conditions for
the three mainstem gages and three major tributary gages considered in the analysis. ........ 27
Figure 6.0-1. Average annual silt/clay loads at the three mainstem gages and the three primary
tributary gages under pre-Project conditions. ....................................................................... 28
Figure 6.0-2. Average annual sand loads at the three mainstem gages and the three primary
tributary gages under pre-Project conditions. ....................................................................... 29
Figure 6.0-3. Average annual gravel loads at the three mainstem gages and the three primary
tributary gages under pre-Project conditions. ....................................................................... 30
Figure 6.0-4. Average annual sand loads at the mainstem (dark blue) and tributary (light blue)
gages, along with the estimated annual sand load from ungaged tributaries, under pre-
Project conditions. Also shown is the accumulated sediment supply to key points along the
reach based on the gaged and ungaged sand loads. .............................................................. 31
Figure 6.0-5. Average annual gravel loads at the mainstem (dark blue) and tributary (light blue)
gages, along with the estimated annual gravel load from ungaged tributaries, under pre-
Project conditions. Also shown is the accumulated sediment supply to key points along the
reach based on the gaged and ungaged gravel loads. ............................................................ 32
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii September 2014
LIST OF APPENDICES
Appendix A: Sediment-transport Data and Regression Summary
Appendix B: Annual Sediment Load Tabular Summary for pre-Project Conditions
Appendix C: Sediment Transport Rating Curves Data
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv September 2014
LIST OF ACRONYMS AND SCIENTIFIC LABELS
Abbreviation Definition
AEA Alaska Energy Authority
cfs cubic feet per second
FERC Federal Energy Regulatory Commission
ILP Integrated Licensing Process
M Million
Mm Millimeter
MVUE Minimum Variance Unbiased Estimator
NEPA National Environmental Policy Act
NGVD National Geodetic Vertical Datum
NWIS National Water Information System
OS Operation Scenario
PRM Project River Mile
RM River Mile
RSP Revised Study Plan
sq mi square mile
USGS U.S. Geological Survey
WY Water Year
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v September 2014
SUMMARY
The purpose of the study effort was to update the sediment load rating curves and preliminary
estimates of the overall sediment balance in the Middle and Lower River segments under pre-
Project conditions that were initially provided in “Development of Sediment-Transport
Relationships and an Initial Sediment Balance for the Middle and Lower Susitna River
Segments,” (Tetra Tech, Inc. 2013a). This update is based on additional data collected by the
U.S. Geological Survey (USGS) in 2012 and 2013. The sediment rating curves are applied in
this memorandum to develop the sediment balance along the Susitna River mainstem and they
will be used as sediment inflow rating curves for the 1-D Fluvial Geomorphology Modeling
Study (Study 6.6) tasks. A sediment balance is the determination of the difference between the
inflowing sediment (supply) to a reach and the outflowing sediment from the reach (transport).
If the sediment inflow to the reach is greater than the outflow, then sediment is stored within the
reach. If the sediment supply into the reach is less than the sediment outflow from the reach,
then sediment is removed from the reach. In the former case, the reach is considered depositional
and in the latter case it is considered aggradational. If the sediment inflow and outflow are nearly
equal, the reach is considered in balance with its sediment supply and transport.
Sediment transport relationships (sediment load versus water discharge) were developed at five
locations on the mainstem Susitna River: Denali, Cantwell (Vee Canyon), Gold Creek, Sunshine,
and Susitna Station, and on the three largest tributaries, the Chulitna, Talkeetna and Yentna
Rivers. Since the ability of the river to transport sediment and its response to the sediment being
supplied varies greatly with the size of the sediment, relationships were developed for three sizes
of sediment, wash load (silts and clay), sand load and gravel load. These are the same size
classes used in the preliminary sediment transport analysis in 2013 (Tetra Tech, Inc. 2013a). Just
as in Tetra Tech, Inc. 2013a, the relationships were applied to the long term hydrologic
conditions represented by existing (pre-Project) conditions. This was done primarily as a check
for consistency with the preliminary analysis. Unlike the 2013 analyses, operational conditions
were not considered as part of this task because 1-D bed evolution modeling will be used to
develop sediment transport information throughout the river between the proposed Watana Dam
location and PRM 29.9 for both existing and operational conditions. The modeling will not only
provide sediment loading for the various scenarios, but will be used to evaluate channel change
(e.g. aggradation, degradation, and sediment gradations) and the resulting changes in hydraulics
(e.g. water surface elevations, flow depths, and flow velocities). All future reach-scale sediment
transport analyses will be performed with the 1-D bed evolution modeling to evaluate pre-Project
to the range of operational scenarios.
The data collected in 2012 and 2013 are very similar to previous data collected by the USGS.
The sediment rating curves have been updated to include all the data, are also similar but are
considered more representative than the earlier rating curves. Therefore, the data and rating
curves are sufficient for all remaining analyses. Except for measurements made in 2014, no
additional data collection will be performed. Any data collected by the USGS in 2014 will be
reviewed, but AEA does not anticipate further revision of the sediment rating curves or
calculations of annual sediment loads reported in this TM.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 September 2014
1. INTRODUCTION
The Alaska Energy Authority (AEA) is preparing a License Application that will be submitted to
the Federal Energy Regulatory Commission (FERC) for the Susitna-Watana Hydroelectric
Project using the Integrated Licensing Process. The Project is located on the Susitna River, an
approximately 300-mile-long river in the south-central region of Alaska. The Project’s dam site
will be located at Project River Mile (PRM) 187.1. The results of this study will provide
information needed to support the FERC’s National Environmental Policy Act analysis for the
Project license.
The 2012 study effort G-S4: Reconnaissance-level Geomorphic and Aquatic Habitat Assessment
of Project Effects on Lower River Channel study plan included, among other objectives, a
preliminary evaluation of the relative magnitude of changes in the sediment regime associated
the Susitna-Watana Hydroelectric Project. The previous memorandum (Tetra Tech 2013a)
summarized work performed under the Sediment Load Comparison section of the Sediment
Transport Assessment task to meet this objective, including the development of sediment-
transport relationships using the available sediment-transport data, and an initial sediment
balance for the Middle and Lower Susitna River segments, based on the pre-Project hydrology
and post-Project hydrology under an operations scenario referred to as Maximum Load
Following Operation Scenario 1 (OS-1). These two hydrology scenarios were analyzed in detail
in Tetra Tech (2013b).
The primary purpose of this technical memorandum is to update the sediment transport
relationships (sediment rating curves) for gages located on the mainstem Susitna River and three
of the gages are located on major tributaries (the Chulitna, Talkeetna and Yentna Rivers). The
update effort is part of the Geomorphology Study (Study 6.5) and is identified as part of RSP
Section 6.5.4.3 Study Component: Sediment Supply and Transport Middle and Lower Susitna
River Segments. The relationships are used to estimate sediment loads along the Susitna River
and contributed from the major tributaries. The primary uses of these relationships are as input
to the 1-D bed evolution modeling and to evaluate model performance at gages located within
the model reaches. The pre-Project sediment load analysis was performed for six streamflow
gages located in the Susitna Basin using 61 years of extended hydrologic records developed by
the U.S. Geological Survey (USGS 2012) for the period from Water Year (WY) 1950 through
WY2010.
The main components of the sediment-transport analysis include the following:
A review of previously published relationships between discharge and (1) suspended
sediment load, (2) bed load, and (3) total sediment load (Knott et al. 1987), and refinement of
those relationships using all additional available data.
Application of selected relationships to both the pre-Project flow records to estimate annual
sediment loads for suspended silt/clay (i.e., wash load), total sand load based on independent
estimates of the amount of sand being carried in suspension and as bed load, and the gravel
component of the bed load.
Comparison of the estimated annual sediment loads to provide an approximate sediment
balance in the river reaches between the mainstem gages in the Middle and Lower Rivers.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 September 2014
2. STUDY OBJECTIVES
The overall objective of this memorandum is to make preliminary estimates of the overall
sediment balance in the Middle and Lower River segments under pre-project conditions
including the specific assessments of the following, interrelated topics:
Determination of the suitability of previously published sediment transport relationships
between discharge and sediment load and update the relationships if necessary.
Selection of the most appropriate sediment transport relationships for use in the preliminary
sediment balance.
Use the selected sediment transport relationships to estimate the pre-Project annual loads.
The sediment loads will be divided into wash load (silt and clay), sand load and gravel load.
Comparison of estimated annual sediment loads at the three mainstem Susitna River gages to
characterize the overall sediment balance under pre-Project conditions.
Provide sediment transport relationships that will be used for 1-D bed morphology modeling
tasks. These will be used as sediment boundary conditions at Watana Dam site and the three
major tributaries (Chulitna, Talkeetna, and Yentna Rivers).
A sediment balance is the determination of the difference between the inflowing sediment
(supply) to a reach and the outflowing sediment from the reach (transport). If the sediment
inflow to the reach is greater than the outflow, then sediment is stored within the reach. If the
sediment supply into the reach is less than the sediment outflow from the reach, then sediment is
removed from the reach. In the former case, the reach is considered depositional and in the latter
case it is considered aggradational. If the sediment inflow and outflow are nearly equal, then the
reach is considered in balance or in equilibrium in terms of sediment supply and transport. Other
sources of sediment, especially tributary sediment inputs, must also be considered. The three
major tributaries are included based on the available data. Minor tributaries may also have
significant local effects and cumulative effects at the reach scale. Minor tributaries will be
incorporated as this information is further developed in 2015.
3. STUDY AREA AND AVAILABLE DATA
The Susitna River, located in Southcentral Alaska, drains an area of approximately 20,010 square
miles and flows about 320 miles from its headwaters at the Susitna, West Fork Susitna and East
Fork Susitna glaciers to the Cook Inlet (USGS 2012). The Susitna River basin is bounded on the
west and north by the Alaska Range, on the east by the Talkeetna Mountains and Copper River
Lowlands and on the south by Cook Inlet. The highest elevations in the basin are at Mt.
McKinley at 20,320 feet while its lowest elevations are at sea level where the river discharges
into Cook Inlet. Major tributaries to the Susitna River between the headwaters and Cook Inlet
include the Chulitna, Talkeetna and Yentna Rivers that are also glacially fed in their respective
headwaters. The basin receives, on average, 35 inches of precipitation annually with average
annual air temperatures of approximately 29oF.
There are 14 USGS streamflow gages located in the Susitna River Basin plus one on the Little
Susitna River that was used as an index station (Table 3.0-1 and Figure 3.0-1). The period of
recorded data available for these gages ranges from 58 years at the Gold Creek gage to less than
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 3 September 2014
10 years at gages such as the Yentna River at Susitna Station and the Susitna River at Sunshine
gages. The data available from many of these gages may not adequately represent long-term
streamflow conditions in the Susitna River Basin because of the short period of record and the
distribution of years during which data were collected (USGS 2012). To provide a consistent
long-term record, the USGS extended the record of 11 of these gages to 61 years (WY1950 –
WY2010). WY1950 was selected for the start of the record because this was the first full water
year of data collection for the primary index station at Gold Creek. The Montana Creek (Mont),
Deception Creek (Decep), and the Deshka River (Desh) gages were not included in the extended
record analysis because they could not be adequately correlated to any long-term index station
for the entire study period (USGS 2012).
Three main stem gages and three primary tributary gages locations downstream of the Project
site PRM 187.1 (Figure 3.0-1) were used to characterize the sediment-transport regime under the
61-year hydrology record for each portion of the reach, as follows:
Main Steam Gages
o Middle River Mainstem: Susitna River at Gold Creek Gage (15292000) and Susitna
River near Talkeetna Gage (15292100)1
o Lower River mainstem below Three Rivers Confluence: Susitna River at Sunshine
Gage (15292780)
o Lower River mainstem below Yentna River: Susitna River at Susitna Station Gage
(15294350)
Primary Tributary Gages
o Tributary Supply to Three River Confluence (Chulitna River near Talkeetna Gage
(15292400) and the Chulitna River below canyon near Talkeetna gage (15292410)1)
o Talkeetna River near Talkeetna Gage (15292700)
o Tributary Supply to Lower River: Yentna River near Susitna Station Gage
(15294345)
Other Locations
o Upper River Mainstem: Susitna River near Denali Gage (15291000)
o Upper River Tributary: Maclaren River near Paxson Gage (15291200)
o Upper River Mainstem: Susitna River near Cantwell Gage (15291500)
o Middle River Tributary: Portage Creek near Gold Creek (625000149223500)2
o Middle River Tributary: Indian Creek near Gold Creek (624718149393600)2
The number and types of sediment samples, and the dates of sampling vary among the gages, but
generally include both the magnitude and gradation of the suspended sediment and bed load for
samples collected between the late-1970s and the late-1980s (Table 3.0-2). The bulk of these
1 Data from both these gages were combined into a single data set for the USGS (Knott et al. 1987) analysis; this approach was
adopted for this preliminary study, as well.
2 Suspended and bed load sampling conducted in WY1984 and reported in Knott et al. (1986).
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 4 September 2014
data that were collected through WY1985 were previously analyzed by Knott et al. (1987). As
part of the current analysis, the available data for each of the gages were downloaded from the
USGS National Water Information System (NWIS) website (http://waterdata.usgs.gov), and
relevant data collected after 1985 were added to the data sets. Data for Portage Creek and Indian
River were obtained from Tables 2 and 3 of Knott et al. (1986).
4. METHODS
This section describes the methods used to select or develop relationships between discharge and
sediment load for each component of the sediment load at the six USGS gaging stations, and
apply these relationships, with the minimum variance unbiased estimator (MVUE) bias-
correction technique, to the pre-Project extended flow records to estimate the annual sediment
loads for each size range.
4.1. Variations from Study Plan
The Study Plan calls for comparison of the total sediment load at the Sunshine and Susitna
Station gaging stations for an average, wet, and dry year between pre-Project and adjusted post-
Project conditions using adjusted post-Project rating curves. Because the 61-year daily flow
record was available for pre-Project and Maximum Load Following OS-1 conditions, the full
record was used for this purpose in lieu of selecting specific years for the analysis, with sediment
loads compared on an average annual basis over all years, and the variability assessed by
considering the range of annual loads from the 61-year record. This more comprehensive
approach to assessing sediment loads provides a better assessment of the long-term project
influence on sediment transport than considering only the three “representative” years.
4.2. Sediment Load Rating Curves
Knott et al. (1987) used the data collected through WY1985 at the six gages to characterize
sediment-transport conditions in the reach. This included development of relationships between
discharge and sediment loads from data for four components of the total sediment load collected
during the period between October 1984 and September 1985, data collected from WY1981
through WY1984, and historical records (USGS 1953 to 1980):
Suspended silt/clay
Suspended sand
Sand bed load,
Gravel bed load
The Knott et al. (1987) relationships were of the power-function form: 𝑄𝑠=𝑎(𝑄)𝑏 (4.2-1)
where:
Qs = sediment load (tons/day)
a = coefficient
b = exponent
Q = discharge (cubic feet/second)
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 5 September 2014
For consistency with Knott et al. (1987) and standard practice in developing sediment load rating
curves (USGS, 1992), power function relationships were also used for the current study.
As an initial step in the analysis, the available data through WY1985 in each size-range at each
of the gages was plotted and compared with the data plots in Knott et al. (1987). This
comparison revealed a limited number of available data points from the NWIS database that
were not used in the Knott et al. (1987) analysis. No explanation was provided in their report for
why these data points were not used. In an attempt to ascertain the reason(s), Mr. Gary Solin at
the USGS Alaska Science Center, where the original data collection and analysis were
performed, was contacted. Mr. Solin indicated that the individuals who performed the analysis
were either retired and out of contact; thus, he was not able to provide specific information about
the issue. He did, however, suggest that the data points used in the analysis were probably
limited to those directly collected by the study team and/or for which the study team had specific
knowledge. Because including the additional, recently (2012 and 2013) collected data is
desirable to develop the most representative sediment load information, all appropriate prior data
were included in this analysis. A data point was excluded when it was an obvious outlier that
significantly impacted the resulting relationship.
The data sets were updated by adding relevant data collected since WY1985 (2014 data have not
been received from the USGS and were not included in the analysis). Power-function regression
lines were then fit to the extended data sets using the least-squares regression technique and
compared to the Knott et al. (1987) line-of-best-fit. The new regression equations are presented
in Table 4.1-1 and Appendix A. In some cases, no relationship was evident. In these cases a
power function relationship was passed through the means of the log-transformed data (a
requirement of linear regression) and a slope was selected that represented the observable trends.
This was only done for some bed load sand and gravel data, which are small in comparison to
suspended load sand.
4.3. Bias Correction and Annual Load Estimates
The selected relationships between discharge and the various components of the sediment load
were then used with the MVUE bias-correction technique to estimate daily sediment loads for
the entire 61-year record of mean daily flows for pre-Project conditions. The MVUE technique
was used to correct for the statistical bias that occurs in basic power-function regression, based
guidance from USGS (1992). Previous studies have demonstrated that the bias occurs in the
process of linearizing the data set by transforming it into the logarithmic domain and then back-
transforming the resulting relationship into the arithmetic domain (Walling 1977b; Thomas
1985; Ferguson 1986). Various procedures are available to address the bias, including accounting
for seasonal differences in sediment transport and accounting for hysteresis related to rising and
falling limbs of flood hydrographs (Guy 1964; Walling 1974). Koch and Smillie (1986) and
Cohn and Gilroy (1991) described methods of numerically correcting for the bias that depend on
the expected distribution of errors. USGS (1992) endorsed the recommendations in Cohn and
Gilroy (1991) to use the MVUE bias correction for normally distributed errors, or the Smearing
Estimator (Duan 1983) when a non-normal error distribution is identified. The MVUE method
was selected in this analysis to remove the bias from the log-transformed sediment loads because
the errors are generally normally-distributed. The MVUE technique was also used to convert the
sediment load regression lines into sediment load rating curves for use as boundary conditions in
the 1-D bed evolution models.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 6 September 2014
5. RESULTS
This section summarizes the annual sediment yields developed using the methods described in
Section 4. As noted above, Knott et al. (1987) divided the total sediment load into four
components, primarily because of the manner in which the data are collected. It is, however,
more meaningful from a river-process perspective to re-group these components into three
components, consisting of the wash load (i.e., silt/clay that is almost exclusively carried in
suspension), the sand component of the bed material load that consists of the sand that is carried
both in suspension and as bed load, and the gravel component of the bed load. The sand load is
being treated separately in this analysis because it may be strongly supply-limited in the Middle
River, and thus more correctly categorized as part of the wash load in the Middle River and some
tributaries; however, in the Lower River especially in the area of Susitna Station and further
downstream, the sand load may be transport limited. The significant presence of sand in the
Lower River and differences between the Middle and Lower River bed material are described in
Tetra Tech (2014). The bed in the Middle River is very armored but the bed in the Lower River
is very mobile.
Under pre-Project conditions, the estimated total annual sediment loads at the Gold Creek/near
Talkeetna gage average about 3.4 million (M) tons, varying from about 680,000 tons to 9.3M
tons (Figure 5.1-1). Of these amounts, the silt/clay, wash load accounts for about 57 percent
(2.0M tons) of the total, on average, while the sand accounts for about 42 percent (1.4M tons)
and the gravel bed load accounts for only about 1 percent (20,000 tons) of the total.
At the Sunshine gage, the average, pre-Project total annual sediment load increases to about
15.8M tons, ranging from about 4.8M to 25.5M tons (Figure 5.1-2). The relative proportion of
wash load increases to about 61 percent (9.6M tons) of the total, with the sand and gravel loads
accounting for about 38 and 1.5 percent (6M and 240,000 tons) of the total, respectively.
The annual total load at the Susitna Station gage averages about 33.7M tons, and ranges from
18.3M to 52M tons (Figure 5.1-3). The silt/clay load accounts for about 58 percent (19.4M
tons), and the sand and gravel loads account for about 42 percent (14.1M tons) and less than 1
percent (169,000 tons) of the total, respectively, at this location.
The three primary tributaries supply a significant amount of the sediment to the mainstem. The
annual load from the Chulitna River, for example, averages about 8.6M tons, ranging from 4.5M
tons to 20.5M tons (Figure 5.1-4), and the Talkeetna River supplies an average of about 1.9M
tons/year, ranging from about 420,000 to 6.9M tons/year (Figure 5.1-5). The Yentna River
carries the largest total load of the three, averaging about 14.5M tons/year and ranging from
8.2M to 25M tons/year (Figure 5.1-6). The transported load in the Chulitna River includes a
higher proportion of gravel than either the mainstem or the other two major tributaries (about 5
percent versus < 1, 2.3 and 1.3 percent for the mainstem, Talkeetna and Yentna Rivers,
respectively). Wash load comprises 48 percent of the sediment transported by the Yentna River
compared to 57 percent on the mainstem, and 60 and 50 percent for the Chulitna and Talkeetna
Rivers, respectively.
Based on these results, the Middle River supplies about 24 percent of the total sediment load to
the Three Rivers Confluence, and the Chulitna and Talkeetna Rivers supply about 62 and 14
percent of the total load, respectively (Figure 5.1-7). On a by-size-fraction basis, the relative
contributions of silt/clay and sand are about the same as the total load; however, the Chulitna
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 7 September 2014
River supplies the bulk of the gravel load that is key to the channel morphology (about 87
percent of the total, compared to about 4 percent from the Middle River and 9 percent from the
Talkeetna River). The total sediment load from the Yentna River represents about 48 percent of
the total load at Susitna Station, and about 44 percent of the gravel load. A tabulation of the
estimated annual loads under pre-Project conditions for each component of the load at each of
the six gages is provided Appendix B.
The tributary loads referenced above assume that these loads are delivered from the point of
measurement, which is well upstream from the tributary mouth in each case (approximately 12, 4
and 12 miles for the Chulitna, Talkeetna, and Yentna Rivers). The lower 8 miles of the Chulitna
and lower 2 miles of both the Talkeetna and Yentna River exhibit channel forms (braid plains,
island and bar systems, and multiple channel networks) that are indicative of long-term sediment
storage. Therefore, the sediment loads associated with these major tributaries are probably not
being entirely delivered to the Susitna River. This is one reason why the 1-D bed evolution
modeling includes the Chulitna and Talkeetna Rivers as individual reaches.
6. DISCUSSION
The sediment load analyses presented in the previous sections provide a basis for development of
a preliminary sediment balance for the Middle and Lower Rivers. In general, sediment rating
curves developed using regression equations tended to have lower slopes than those presented in
Knott et al. (1987), which were predominantly used in the prior analyses (Tetra Tech 2013a).
This results in very comparable long-term loads (mean annual) but tends to decrease loads for
high flow years and increase loads for low flow years.
This Technical Memorandum completes Study Component described in RSP (AEA 2012)
Section 6.5.4.2, Bedload and Suspended Load Data Collection at Tsusena Creek, Gold Creek
and Sunshine Gage Stations on the Susitna River, Chulitna River near Talkeetna, ant he
Talkeetna River near Talkeetna. The data collected in 2012 and 2013 are very similar to
previous data. Although the regression analyses included in this TM generally produce lower
slopes than the earlier USGS relationships, it is the improved method of analysis, rather than the
data, that produces the change. The sediment rating curves were updated to include all the data
and are considered more representative of transport conditions than the earlier rating curves. The
data and rating curves are sufficient for all remaining analyses. Except for measurements made
in 2014, no additional sediment transport measurements will be performed. Any data collected
by the USGS in 2014 will be reviewed, but AEA does not anticipate further revision of the
sediment rating curves or calculations of annual sediment loads reported in this TM.
The effects of the dam on the sediment balance would vary between the silt/clay, sand and gravel
loads and will be evaluated based on sediment transport modeling. Initial estimates are that the
dam would likely cut off at least 90 percent of the silt/clay supply and essentially all of the sand
and gravel supply to the head of the Middle River. The effects on all components of the sediment
load would diminish in the downstream direction due to contributions from the tributaries and
entrainment of material that is currently stored in the channel. The silt/clay load is carried
almost exclusively in suspension. As a result, the effects of sediment trapping in the reservoir on
downstream silt/clay loads would be felt within a very short time-frame (i.e., on the order of the
travel time of the water) throughout the Middle and Lower Rivers after closure of the dam.
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 8 September 2014
A significant change in this analysis from the initial sediment balance analysis (Tetra Tech
2013a) is in the estimates of ungaged tributary loads. In the initial sediment balance the loads
were estimated based on assuming sediment loading in proportion to drainage area. This is
appropriate for reasonably similar basin conditions, but in this instance does not address
differences in glaciated versus non-glaciated basins. Field observations indicate that other than
the Chulitna, Talkeetna, and Yentna Rivers, the Middle and Lower River tributaries are clear-
water supplying virtually no wash load and little sand to the Susitna River. Data were collected
by the USGS at Portage Creek and Indian River in 1984 and are presented in Table 6.0-1. These
data are in significant contrast to the mainstem sediment conditions. Where the mainstem and
major tributaries are dominated by wash load and sand with orders of magnitude less gravel, the
Middle River tributaries have negligible amounts of wash load (silt/clay), slightly higher
amounts of sand, and yet larger amounts of gravel.
The information from Section 5 was used to develop a preliminary sediment balance for the
Lower and Middle Rivers under pre-Project and presented in Table 6.0-1. Ungaged tributaries
between the Watana Dam site and the Gold Creek gage account for about 16 percent of the total
drainage at Gold Creek, and ungaged tributaries between Sunshine and Susitna Station account
for about 11 percent of the total drainage area at Susitna Station. Sediment loading from the
Middle River tributaries is based on 3ppm silt/clay, 7 ppm sand, and 20 ppm gravel. For the
wash load and sand, the loads are negligible. For the gravel, the loading from tributaries exceeds
the transport capacity at the lower end of the Middle River. If this is actually the case, then the
gravel is either being stored in fans at the tributary mouths, or is being stored along the Middle
River channel. Although fan storage is considered more likely, if the entire 34,000 tons/year of
tributary-supplied gravel at 100 lb/ft3 bulk weight were distributed over a 600 ft channel width
and 70 miles of the Middle River (excluding Devils Canyon), the resulting aggradation would
average only 0.3 ft in 100 years.
For the Lower River it was assumed that all ungaged tributary loads are negligible. In many
cases these tributaries cross terraces before feeding into side channels. There are also no
significant fan deposits at these tributaries. Although these estimates are low, the amounts of
sediment delivered from non-major tributaries is insignificant compared to the Susitna River
transport. Sediment transport models are being developed to estimate tributary sediment supply
to the Lower River, but field observations indicate that these loads are minimal for all but the
major tributaries. These results do bring into question some of the values in Table 6.0-2,
primarily when the supply above Sunshine (or Susitna Station) is less than the amount computed
at Sunshine (or Susitna Station). Although these differences could be attributed to tributary
inputs, other factors could be contributing to these differences. The factors include bank erosion
into terraces, landslides that briefly produce large amounts of sediment, or uncertainties in
computing the loads. The differences are less than 10 percent for total load, which for sediment
load estimates is well within the uncertainties.
To demonstrate the differences between the glacially fed source areas and minor tributaries,
Table 6.0-3 shows mean annual sediment concentrations in PPM by weight. At low
concentrations these PPM values are essentially the same as concentration in mg/l. In table 6.0-3
silt/clay loads along the Susitna River and its major tributaries range from 200 to 600 PPM, sand
loads range from 150 to 500 ppm, and gravel from 3 to 50 PPM. This compares to less than 10
PPM for silt/clay and sand for the measurements at Indian River and Portage Creek and
generally between 10 and 20 ppm for gravel. In terms of sediment concentration (weight of
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 9 September 2014
sediment divided by the weight of water-sediment mixture), the Middle River tributary flows
may contain only 0.01 times the concentration of silt/clay, 0.04 times the concentration of sand,
but as much as 10 times the gravel than mainstem Middle River flows. The values for ungaged
Middle and Lower River tributaries will be refined using sediment transport capacity calculations
for surveyed tributaries.
These analyses will be used to support the following analyses:
1. The updated sediment-transport rating curves for Watana dam location and the major
tributary gages will be used as inputs to the reach-scale 1-D sediment-transport model. The
rating tables are presented in Appendix C of this report.
2. The updated sediment-transport rating curves for the mainstem gages will be used to
calibrate the sediment-transport rates in the reach-scale 1-D sediment-transport model.
3. In the current analysis, sediment loading from all ungaged sources was lumped into the
“ungaged tributary” category. In reality, sediment is also supplied to the river from bank
erosion and mass wasting from unstable hillslopes. Estimates of the sediment loading from
all of these sources, including the ungaged tributaries, will be segregated and improved based
on field observations, evaluation of lateral bankline shifting and bed material measurements
and transport capacity calculations in the lower end of a selected number of the larger
ungaged tributaries. As described in RSP Section 6.6.4.1.2.6 (AEA 2012), sediment-load
rating curves for the ungaged tributaries will be developed by surveying cross sections and
collecting bed material samples in an appropriate reach near the mouth, developing 1-D
hydraulic conditions using either step-backwater or normal depth calculations, as appropriate,
and applying an appropriate bed material transport equations with the measured bed material
gradations. For those tributaries that enter the river within the Focus Areas, the hydraulic
and sediment-transport analysis to assess the response of the Susitna River channel to Project
conditions will be performed using the 2-D model(s). For the selected tributaries outside the
focus areas, the analysis will be performed using 1-D hydraulic modeling with relatively
closely spaced cross sections in the vicinity of the confluence.
4. The tributary-specific sediment loads estimated in the previous task will be used to assess the
potential impact of changes in flow and sediment load in the mainstem on the sediment-
transport behavior at the tributary mouths. A key question to be answered by this analysis is
the extent to which the coarse-grained sediment from the tributaries will be entrained and
transported downstream away from the tributary mouth versus building of the delta in a
manner that could potentially affect fish passage into the tributary and/or constrict the river
causing other impacts to water-surface elevations and channel stability. Similar to the
sediment loading analysis, the analysis for those tributaries that are located within a Focus
Area will be conducted using the 2-D mobile-boundary model. At the selected tributaries
outside the Focus Areas, additional mainstem cross sections (typically 5 to 7, in total) will be
surveyed in the vicinity of the mouth, and 1-D hydraulic modeling and sediment-transport
calculations will used to perform the assessment.
5. AEA has extended the 1-D sediment-transport model downstream to at least Susitna Station
(PRM 29) (Tetra Tech 2013c). Based on bed material samples, the bed is primarily gravel
with median (D50) size in the range of 50 to 100 millimeters (mm), and only a small amount
of sand (typically <5 percent) at Sunshine. In contrast, the bed material at Susitna Station is
primarily sand (D50~0.4 mm and nearly 90 percent <2 mm based on one sample). This
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 10 September 2014
indicates aggradation of gravel sizes between Sunshine and Susitna Station. The results for
sand are not as clear. Although from the rating curve analysis it appears that sand may be in
balance along the lower river, the channel form indicates potential for aggradation. This
determination will be important in understanding potential Project effects and will be based
on the sediment transport modeling results. The sediment-transport behavior of mainstem at
the tributary mouths will also be an important factor in understanding Project effects in the
Middle and Lower Rivers, particularly in the reaches upstream from the gravel-sand
transition zone.
The 1-D bed morphology modeling will be an important tool in making comparisons of pre-
Project and the range of operational scenarios, as well as providing input to the detailed Focus
Area (2-D) bed morphology models. The sediment-transport relationships contained in this
Technical Memorandum are a key input for the 1-D bed morphology models, which will be used
for all future reach-scale sediment transport analyses.
7. REFERENCES
AEA (Alaska Energy Authority). 2012. Revised Study Plan: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. December 2012. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/study-plan.
Cohn, T.A., and E.J. Gilroy. 1991. Estimating Loads from Periodic Records. U.S. Geological
Survey Branch of Systems Analysis Technical Report 91.01. 81 p.
Duan, N. 1983. Smearing Estimate: A Nonparametric Retransformation Method. Journal of the
American Statistical Association, v 78(383): 605–610.
Ferguson, R.I. 1986. River Loads Underestimated by Rating Curves. Water Resources Research,
v 22(1): 74–76.
Guy, H.P. 1964. An Analysis of Some Storm-Period Variables Affecting Stream Sediment
Transport. U.S. Geological Survey Professional Paper No. 462E.
Interagency Advisory Committee on Water Data (IACWD). 1982. Guidelines for determining
flow frequency: Reston, Va., U.S. Geological Survey, Office of Water Data
Coordination, Hydrology Subcommittee Bulletin 17B.
Koch, R.W. and G.M. Smillie. 1986. Bias in Hydrologic Prediction Using Log-Transformed
Regression Models. Journal of the American Water Resources Association. v 22: 717–
723.
Knott, J.M., S.W. Lipscomb, and T.W. Lewis. 1986. Sediment Transport Characteristics of
Selected Streams in the Susitna River Basin, Alaska: October 1983 to September 1984.
U.S. Geological Survey Open-File Report 86-424W. Prepared in cooperation with the
Alaska Power Authority. Anchorage, Alaska. 73 p.
Knott, J.M., S.W. Lipscomb, and T.W. Lewis. 1987. Sediment Transport Characteristics of
Selected Streams in the Susitna River Basin, Alaska: Data for Water Year 1985 and
Trends in Bed-load Discharge, 1981-95. U.S. Geological Survey Open-File Report 87-
229. Prepared in cooperation with the Alaska Power Authority. Anchorage, Alaska. 51 p.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 11 September 2014
MWH. 2012. Susitna-Watana Hydroelectric Project, Preliminary Susitna River Pre-Project and
Post-Project Flow Stages, presented at Technical Work Group Meetings, October 23-25.
Tetra Tech, Inc. 2013a Development of Sediment-Transport Relationships and an Initial
Sediment Balance for the Middle and Lower Susitna River Segments (FERC No. 14241).
Prepared for Alaska Energy Authority, 39 p. plus appendices.
Tetra Tech, Inc. 2013b. Streamflow Assessment, Susitna-Watana Hydroelectric Project (FERC
No. 14241). Prepared for Alaska Energy Authority, 94 p. plus appendices.
Tetra Tech, Inc. 2013c. Reconnaissance Level Assessment of Potential Channel Change in the
Lower Susitna River Segment, Susitna-Watana Hydroelectric Project (FERC No. 14241).
Prepared for Alaska Energy Authority.
Tetra Tech, Inc. 2014. Winter Sampling of Main Channel Bed Material, Susitna-Watana
Hydroelectric Project (FERC No. 14241). Prepared for Alaska Energy Authority.
Thomas, R.B. 1985. Estimating Total Suspended Sediment Yield with Probability Sampling.
Water Resources Research. v 21(9): 1381–1388.
U.S. Geological Survey. 1992. Recommendations for Use of Retransformation Methods in
Regression Models Used to Estimated Sediment Loads [“The Bias Correction Problem”].
Office of Surface Water Technical Memorandum No. 93.08. December 31.
U.S. Geological Survey. 2012. Streamflow Record Extension for Selected Streams in the
Susitna River Basin, Alaska (Scientific Investigations Report 2012–5210).
Walling, D.E. 1974. Suspended Sediment and Solute Yields from a Small Catchment Prior to
Urbanization. Institute of British Geographers Special Publication No. 6: 169–192.
Walling, D.E. 1977a. Limitations of the Rating Curve technique for Estimating Suspended
Sediment Loads, with Particular Reference to British Rivers. In: Erosion and Solid Matter
Transport in Inland Waters, Proceedings of Paris Symposium. July. IAHS Publication
No. 122: 34–48.
Walling, D.E. 1977b. Assessing the Accuracy of Suspended Sediment Rating Curves for a Small
Basin. Water Resources Research. v 13(3): 531–538.
Wolman, M.G. and J.P. Miller. 1960. Magnitude and frequency of forces in geomorphic
processes. Journal of Geology. v 68(1): 54–74.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 12 September 2014
8. TABLES
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 13 September 2014
Table 3.0-1. List of streamflow gages.
Gage Number Gage Name
Drainage Area (sq mi)
Gage Datum (NGVD 29, feet) Latitude Longitude Available Record Extended
Record
Main Stem
River Mile
15290000 Little Susitna River near Palmer 63 917 61o 42' 37" 149o 13' 47" 1948 - 2011 -
15291000 Susitna River near Denali 950 2,440 63o 06' 14" 147o 30' 57" 1957 - 1966; 1968 - 1986 Yes 291
15291200 Maclaren River near Paxson 280 2,866 63o 07' 10" 146o 31' 45" 1958 - 1986 Yes -
15291500 Susitna River near Cantwell 4,140 1,900 62o 41' 55" 147o 32' 42" 1961 - 1972; 1980 - 1986 Yes 223
15292000 Susitna River at Gold Creek 6,160 677 62o 46' 04" 149o 41' 28" 1949 - 1996; 2001 – 2014 Yes 136
15292400 Chulitna River near Talkeetna 2,570 520 62o 33' 31" 150o 14' 02" 1958 - 1972; 1980 - 1986,
2012-2014 Yes -
15292700 Talkeetna River near Talkeetna 1,996 400 62o 20' 49" 150o 01' 01" 1964 – 2013 Yes -
15292780 Susitna River at Sunshine 11,100 270 62o 10' 31.3" 150o 10' 13.5" 1981 - 2014 Yes 84
15292800 Montana Creek near Montana 164 250 62o 06' 19" 150o 03' 27" 2005 - 2006; 2008 - 2011 -
15294005 Willow Creek near Willow 166 350 61o 46' 51" 149o 53' 04" 1978 - 1993; 2001 - 2011 Yes -
15294010 Deception Creek near Willow 48 250 61o 44' 52" 149o 56' 14" 1978 - 1985 -
15294100 Deshka River near Willow 591 80 61o 46' 05" 150 20' 13" 1978 - 1986; 1998 - 2001 -
15294300 Skwentna River near Skwentna 2,250 200 61o 52' 23" 151 22' 01" 1959 - 1982 Yes -
15294345 Yentna River near Susitna Station 6,180 80 61o 41' 55" 150 39' 02 1980 - 2014 Yes -
15294350 Susitna River at Susitna Station 19,400 40 61o 32' 41" 150 30' 45 1974 - 2014 Yes 28
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 14 September 2014
Table 3.0-2. Sediment-transport data summary.
Gage
Number Gage Name
Number of Samples
Record Suspended Silt/Clay Suspended Sand Bed-load Sand Bed-load Gravel
Pre-2012 2012/2013 Pre-2012 2012/2013 Pre-2012 2012/2013 Pre-2012 2012/2013
15292000 Susitna River at Gold Creek 50 13 51 13 42 9 37 9 1962 - 2013
15292400 Chulitna River near Talkeetna 50 11 48 11 46 8 46 8 1973 - 2013
15292700 Talkeetna River near Talkeetna 76 6 78 6 44 5 38 4 1967 - 2013
15292780 Susitna River at Sunshine 54 11 55 11 47 10 47 10 1971 - 2013
15294345 Yentna River near Susitna Station 24 5 24 5 11 4 11 4 1981 - 2013
15294350 Susitna River at Susitna Station 46 5 44 5 15 4 13 4 1975 - 2013
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 15 September 2014
Table 4.1-1. Summary of sediment load relationships used for the analysis.
Gage Number Gage Name Suspended Load Bed Load
Silt/Clay Sand Sand Gravel
15292000 Susitna River at Gold
Creek
2.11E-8 Q2.67 2.90E-11 Q3.29 1.86E-6 Q1.85 2.45E-18 Q4.34
n = 63 (50/13), R2 = 0.74 n = 64 (51/13), R2 = 0.86 n = 51 (42/9), R2 = 0.40 n = 46 (37/9), R2 = 0.46
15292400 Chulitna River near
Talkeetna
2.18E-7 Q2.59 8.46E-6 Q2.16 0.12 Q1.00 (see note below) 7.20E-6 Q2.00 (see note
below)
n = 61 (50/11), R2 = 0.90 n = 59 (48/11), R2 = 0.86 n = 54 (46/8) n = 54 (46/8)
15292700 Talkeetna River near
Talkeetna
2.75E-8 Q2.79 2.48E-6 Q2.32 2.78E-2 Q1.08 1.94E-10 Q2.99
n = 82 (76/6), R2 = 0.76 n = 84 (78/6), R2 = 0.86 n = 49 (44/5), R2 = 0.30 n = 42 (38/4), R2 = 0.65
15292780 Susitna River at
Sunshine
4.97E-8 Q2.54 3.60E-6 Q2.10 6.65 Q0.48 5.08E-4 Q1.32
n = 65 (54/11), R2 = 0.82 n = 66 (55/11), R2 = 0.83 n = 57 (47/10), R2 = 0.09 n = 57 (47/10), R2 = 0.20
15294345 Yentna River near
Susitna Station
6.10E-7 Q2.33 7.90E-3 Q1.43 1.47E+3 Q0.15 1.03E-7 Q2.32 (see note
below)
n = 29 (24/5), R2 = 0.91 n = 29 (24/5), R2 = 0.88 n = 15 (11/4), R2 = 0.03 n = 15 (11/4)
15294350 Susitna River at
Susitna Station
7.13E-8 Q2.42 1.77E-3 Q1.52 4.60E-1 Q0.83 2.98E-5 Q1.50
n = 51 (46/5), R2 = 0.86 n = 49 (44/5), R2 = 0.74 n = 19 (15/4), R2 = 0.46 n = 17 (13/4), R2 = 0.62
Notes:
Note: Relationships noted above do not use a least squares regression. These relationships use one or more lines of best fit to estimate transported material.
Sediment load in tons/day (tpd)
Q = Water discharge in cfs
n = Total number of sample points (pre-2012 data/2012 & 2013 data)
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 16 September 2014
Table 6.0-1. 1984 sediment transport measurements at Portage Creek and Indian River (Knott et al. 1986).
Location Date Q (cfs) Qs (t/d) Sorted (t/d) Concentration, PPM-wt
Silt/Clay Sand Gravel Silt/Clay Sand Gravel Total
Portage Creek
30-May-84 597 21.4 4.4 6.4 10.7 3 4 7 13
26-Jun-84 1440 96 4.0 37.6 54.4 1 10 14 25
24-Jul-84 782 53.3 4.7 8.6 40.0 2 4 19 25
27-Sep-84 392 7.5 6.4 1.1 0.0 6 1 0 7
Indian River
30-May-84 339 7.3 1.8 3.7 1.7 2 4 2 8
27-Jun-84 481 36.6 0.9 9.8 25.8 1 8 20 28
25-Jul-84 388 22.1 1.7 7.1 13.3 2 7 13 21
27-Sep-84 195 1.6 1.1 0.5 0.0 2 1 0 3
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 17 September 2014
Table 6.0-2. Comparison of average annual sediment loads under pre-Project conditions.
Gage1 Drainage Area (mi2)
Water Discharge
(acre-ft)
Average Annual Load (tons)
Wash Load Bed Material Total Load Silt/Clay Sand Gravel Total
Denali2 950 2,017,000 1,662,000 1,294,000 NA NA 2,957,000
Maclaren2 280 711,000 324,000 183,000 NA NA 507,000
Cantwell (Vee Canyon)2 4,140 4,486,000 2,688,000 1,981,000 NA NA 4,669,000
Watana 5,180 5,803,000 1,952,000 1,443,000 20,000 1,463,000 3,415,000
Ungaged Tributaries 980 1,242,000 5,000 12,000 34,000 46,000 51,000
Supply above Gold Creek 6,160 7,045,000 1,957,000 1,455,000 54,000 1,509,000 3,466,000
Gold Creek/Susitna nr Talkeetna 6,160 7,045,000 1,952,000 1,443,000 20,000 1,463,000 3,415,000
Talkeetna 1,996 2,938,000 950,000 921,000 45,000 966,000 1,916,000
Chulitna 2,570 6,231,000 5,195,000 2,985,000 429,000 3,414,000 8,609,000
Supply above Sunshine 10,726 16,213,000 8,097,000 5,349,000 495,000 5,844,000 13,941,000
Sunshine 11,100 17,426,000 9,627,000 5,958,000 239,000 6,197,000 15,824,000
Ungaged Tributaries 2,120 3,654,000 0 0 0 0 0
Yentna 6,180 14,102,000 6,918,000 7,392,000 191,000 7,583,000 14,500,000
Supply above Susitna Station 19,400 35,182,000 16,545,000 13,350,000 430,000 13,779,000 30,324,000
Susitna Station 19,400 35,182,000 19,401,000 14,149,000 169,000 14,318,000 33,719,000
Notes:
1 Susitna River gages are shown in bold.
2 Only suspended sediment measurements were collected at these locations. No bed-load data are available.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 18 September 2014
Table 6.0-3. Comparison of sediment concentration under pre-Project conditions.
Gage1 Drainage Area (mi2)
Water Discharge
(acre-ft)
Average Annual Sediment Concentration (PPM-wt)
Wash Load Bed Material Total Load Silt/Clay Sand Gravel Total
Denali2 950 2,017,000 606 472 NA NA 1,078
Maclaren2 280 711,000 335 189 NA NA 524
Cantwell (Vee Canyon)2 4,140 4,486,000 441 325 NA NA 765
Watana 5,180 5,803,000 247 183 3 185 433
Ungaged Tributaries 980 1,242,000 3 7 20 27 30
Supply above Gold Creek 6,160 7,045,000 204 152 6 158 362
Gold Creek/Susitna nr Talkeetna 6,160 7,045,000 204 151 2 153 357
Talkeetna 1,996 2,938,000 238 231 11 242 480
Chulitna 2,570 6,231,000 613 352 51 403 1,016
Supply above Sunshine 10,726 16,213,000 367 243 22 265 632
Sunshine 11,100 17,426,000 406 251 10 261 668
Ungaged Tributaries 2,120 3,654,000 0 0 0 0 0
Yentna 6,180 14,102,000 361 385 10 395 756
Supply above Susitna Station 19,400 35,182,000 346 279 9 288 634
Susitna Station 19,400 35,182,000 405 296 4 299 705
Notes:
1 Susitna River gages are shown in bold.
2 Only suspended sediment measurements were collected at these locations. No bed-load data are available.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 19 September 2014
9. FIGURES
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 20 September 2014
Figure 3.0-1. Susitna River study area and large-scale river segments.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 21 September 2014
Figure 5.1-1. Estimated annual silt/clay, sand and gravel loads at the Gold Creek (Gage No. 15292000)/, Susitna River near Talkeetna (Gage No. 15292100) gage over
the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 22 September 2014
Figure 5.1-2. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Sunshine (Gage No. 15292780) gage over the 61-year period of flows under pre-
Project conditions. Also shown is the annual flow volume for each of the years.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 23 September 2014
Figure 5.1-3. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Susitna Station (Gage No. 15294350) gage over the 61-year period of flows under
pre-Project conditions. Also shown is the annual flow volume for each of the years.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 24 September 2014
Figure 5.1-4. Estimated annual silt/clay, sand and gravel loads at the Chulitna River near Talkeetna (Gage No. 15292400), Chulitna River below Canyon near Talkeetna
(Gage No. 15292410) gage over the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 25 September 2014
Figure 5.1-5. Estimated annual silt/clay, sand and gravel loads at the Talkeetna River near Talkeetna (Gage No. 15292700) gage over the 61-year period of flows under
pre-Project conditions. Also shown is the annual flow volume for each of the years.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 26 September 2014
Figure 5.1-6. Estimated annual silt/clay, sand and gravel loads at the Yentna River near Susitna Station (Gage No. 15294345) gage over the 61-year period of flows
under pre-Project conditions. Also shown is the annual flow volume for each of the years.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 27 September 2014
Figure 5.1-7. Average annual silt/clay, sand and gravel loads under pre-Project conditions for the three mainstem gages and three major tributary gages considered in
the analysis.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 28 September 2014
Figure 6.0-1. Average annual silt/clay loads at the three mainstem gages and the three primary tributary gages under pre-Project conditions.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 29 September 2014
Figure 6.0-2. Average annual sand loads at the three mainstem gages and the three primary tributary gages under pre-Project conditions.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 30 September 2014
Figure 6.0-3. Average annual gravel loads at the three mainstem gages and the three primary tributary gages under pre-Project conditions.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 31 September 2014
Figure 6.0-4. Average annual sand loads at the mainstem (dark blue) and tributary (light blue) gages, along with the estimated annual sand load from ungaged
tributaries, under pre-Project conditions. Also shown is the accumulated sediment supply to key points along the reach based on the gaged and ungaged sand loads.
TECHNICAL MEMORANDUM SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 32 September 2014
Figure 6.0-5. Average annual gravel loads at the mainstem (dark blue) and tributary (light blue) gages, along with the estimated annual gravel load from ungaged
tributaries, under pre-Project conditions. Also shown is the accumulated sediment supply to key points along the reach based on the gaged and ungaged gravel loads.
APPENDIX A. SEDIMENT TRANSPORT DATA AND REGRESSION
SUMMARY
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Geomorphology Study (Study 6.5)
2014 Update of Sediment-Transport Relationships
and a Revised Sediment Balance for the
Middle and Lower Susitna River Segments
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
Tetra Tech, Inc.
September 2014
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.1 September 2014
Figure A.1. Suspended silt/clay sediment-transport data and rating equation for Susitna River at Gold Creek and Susitna River near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.2 September 2014
Figure A.2. Suspended sand sediment-transport data and rating equation for Susitna River at Gold Creek and Susitna River near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.3 September 2014
Figure A.3. Bed-load Sand sediment-transport data and rating equation for Susitna River at Gold Creek and Susitna River near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.4 September 2014
Figure A.4. Bed-load gravel sediment-transport data and rating equation for Susitna River at Gold Creek and Susitna River near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.5 September 2014
Figure A.5. Suspended silt/clay sediment-transport data and rating equation for Chulitna River near Talkeetna and Chulitna River below Canyon near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.6 September 2014
Figure A.6. Suspended sand sediment transport data and rating equation for Chulitna River near Talkeetna and Chulitna River below Canyon near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.7 September 2014
Figure A.7. Bed-load sand sediment-transport data and rating equation for Chulitna River near Talkeetna and Chulitna River below Canyon near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.8 September 2014
Figure A.8. Bed-load gravel sediment-transport data and rating equation for Chulitna River near Talkeetna and Chulitna River below Canyon near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.9 September 2014
Figure A.9. Suspended silt/clay sediment-transport data and rating equation for Talkeetna River near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.10 September 2014
Figure A.10. Suspended sand sediment-transport data and rating equation for Talkeetna River near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.11 September 2014
Figure A.11. Bed-load sand sediment-transport data and rating equation for Talkeetna River near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.12 September 2014
Figure A.12. Bed-load gravel sediment-transport data and rating equation for Talkeetna River near Talkeetna
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.13 September 2014
Figure A.13. Suspended silt/clay sediment-transport data and rating equation for Susitna River at Sunshine
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.14 September 2014
Figure A.14. Suspended sand sediment-transport data and rating equation for Susitna River at Sunshine
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.15 September 2014
Figure A.15. Bed-load sand sediment-transport data and rating equation for Susitna River at Sunshine
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.16 September 2014
Figure A.16. Bed-load gravel sediment-transport data and rating equation for Susitna River at Sunshine
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.17 September 2014
Figure A.17. Suspended silt/clay sediment-transport data and rating equation for Yentna River near Susitna Station
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.18 September 2014
Figure A.18. Suspended sand sediment-transport data and rating equation for Yentna River near Susitna Station
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.19 September 2014
Figure A.19. Bed-load sand sediment-transport data and rating equation for Yentna River near Susitna Station
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.20 September 2014
Figure A.20. Bed-load gravel sediment-transport data and rating equation for Yentna River near Susitna Station
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.21 September 2014
Figure A.21. Suspended silt/clay sediment-transport data and rating equation for Susitna River near Susitna Station
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.22 September 2014
Figure A.22. Suspended sand sediment-transport data and rating equation for Susitna River near Susitna Station
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.23 September 2014
Figure A.23. Bed-load sand sediment-transport data and rating equation for Susitna River near Susitna Station
APPENDIX A SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page A.24 September 2014
Figure A.24. Bed-load gravel sediment-transport data and rating equation for Susitna River near Susitna Station
APPENDIX B. ANNUAL SEDIMENT LOAD TABULAR SUMMARY FOR
PRE-PROJECT CONDITIONS
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Geomorphology Study (Study 6.5)
2014 Update of Sediment-Transport Relationships
and a Revised Sediment Balance for the
Middle and Lower Susitna River Segments
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
Tetra Tech, Inc.
September 2014
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.1 September 2014
Table B.1. Annual Sediment Load for Pre-Project Conditions for Susitna River at Gold Creek
Susitna River at Gold Creek -15292000
WY
Water
Volume
(acre-ft)
Suspended Load Bed Load
Total LoadSilt/Clay Sand Total Sand Gravel Total
1950 5,810,000 1,090,000 646,000 1,736,000 28,900 6,390 35,290 1,771,290
1951 6,590,000 1,480,000 908,000 2,388,000 36,700 9,490 46,190 2,434,190
1952 6,920,000 2,220,000 1,620,000 3,840,000 44,500 22,700 67,200 3,907,200
1953 7,310,000 1,680,000 1,050,000 2,730,000 40,800 11,700 52,500 2,782,500
1954 7,010,000 1,700,000 1,090,000 2,790,000 40,100 12,300 52,400 2,842,400
1955 7,430,000 2,480,000 1,870,000 4,350,000 48,200 28,200 76,400 4,426,400
1956 8,310,000 3,100,000 2,320,000 5,420,000 59,200 33,800 93,000 5,513,000
1957 7,520,000 2,060,000 1,390,000 3,450,000 45,300 17,300 62,600 3,512,600
1958 6,860,000 1,640,000 1,100,000 2,740,000 37,400 14,000 51,400 2,791,400
1959 7,650,000 2,700,000 2,080,000 4,780,000 51,600 32,300 83,900 4,863,900
1960 7,030,000 1,640,000 1,060,000 2,700,000 38,700 12,600 51,300 2,751,300
1961 7,830,000 2,110,000 1,480,000 3,590,000 45,800 20,200 66,000 3,656,000
1962 8,370,000 3,820,000 3,460,000 7,280,000 61,600 68,200 129,800 7,409,800
1963 8,020,000 2,850,000 2,130,000 4,980,000 54,900 31,000 85,900 5,065,900
1964 7,100,000 4,460,000 4,720,000 9,180,000 58,500 109,000 167,500 9,347,500
1965 7,360,000 2,140,000 1,460,000 3,600,000 46,000 18,500 64,500 3,664,500
1966 6,830,000 2,040,000 1,550,000 3,590,000 41,100 24,400 65,500 3,655,500
1967 8,120,000 3,440,000 2,890,000 6,330,000 59,600 51,500 111,100 6,441,100
1968 7,110,000 2,110,000 1,500,000 3,610,000 43,700 20,200 63,900 3,673,900
1969 4,050,000 442,000 220,000 662,000 14,800 1,580 16,380 678,380
1970 5,500,000 1,070,000 634,000 1,704,000 28,000 6,270 34,270 1,738,270
1971 7,420,000 3,500,000 3,230,000 6,730,000 54,800 64,500 119,300 6,849,300
1972 7,880,000 2,860,000 2,410,000 5,270,000 51,500 43,600 95,100 5,365,100
1973 5,850,000 1,400,000 966,000 2,366,000 31,600 12,900 44,500 2,410,500
1974 5,520,000 1,030,000 609,000 1,639,000 27,200 6,200 33,400 1,672,400
1975 7,440,000 2,250,000 1,560,000 3,810,000 47,200 20,300 67,500 3,877,500
1976 5,930,000 1,150,000 691,000 1,841,000 29,700 7,150 36,850 1,877,850
1977 7,320,000 2,440,000 1,870,000 4,310,000 47,000 28,800 75,800 4,385,800
1978 5,930,000 863,000 465,000 1,328,000 25,600 3,880 29,480 1,357,480
1979 6,870,000 1,820,000 1,230,000 3,050,000 40,400 15,000 55,400 3,105,400
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.2 September 2014
Susitna River at Gold Creek -15292000
WY
Water
Volume
(acre-ft)
Suspended Load Bed Load Total Load
Silt/Clay Sand Total Sand Gravel Total
1980 7,780,000 2,400,000 1,750,000 4,150,000 48,600 24,900 73,500 4,223,500
1981 8,660,000 3,600,000 3,020,000 6,620,000 61,800 52,400 114,200 6,734,200
1982 7,000,000 1,550,000 976,000 2,526,000 37,800 10,800 48,600 2,574,600
1983 7,180,000 1,590,000 990,000 2,580,000 38,800 10,700 49,500 2,629,500
1984 6,950,000 1,650,000 1,110,000 2,760,000 37,900 14,000 51,900 2,811,900
1985 7,150,000 1,910,000 1,300,000 3,210,000 41,900 16,400 58,300 3,268,300
1986 6,180,000 1,040,000 583,000 1,623,000 29,100 5,210 34,310 1,657,310
1987 7,640,000 1,980,000 1,330,000 3,310,000 44,500 16,500 61,000 3,371,000
1988 7,420,000 1,970,000 1,310,000 3,280,000 44,200 15,600 59,800 3,339,800
1989 7,420,000 1,680,000 1,050,000 2,730,000 40,700 11,600 52,300 2,782,300
1990 9,420,000 3,370,000 2,500,000 5,870,000 65,400 35,800 101,200 5,971,200
1991 6,180,000 1,220,000 746,000 1,966,000 31,000 7,850 38,850 2,004,850
1992 6,330,000 1,360,000 848,000 2,208,000 33,200 9,070 42,270 2,250,270
1993 7,310,000 1,700,000 1,070,000 2,770,000 40,700 11,700 52,400 2,822,400
1994 7,210,000 1,720,000 1,170,000 2,890,000 39,300 15,300 54,600 2,944,600
1995 7,450,000 1,790,000 1,150,000 2,940,000 42,100 13,100 55,200 2,995,200
1996 4,940,000 591,000 295,000 886,000 19,400 2,120 21,520 907,520
1997 6,370,000 1,410,000 874,000 2,284,000 34,300 9,350 43,650 2,327,650
1998 6,790,000 1,690,000 1,080,000 2,770,000 39,300 12,200 51,500 2,821,500
1999 6,730,000 1,570,000 1,020,000 2,590,000 36,900 12,100 49,000 2,639,000
2000 7,430,000 2,100,000 1,470,000 3,570,000 44,800 19,100 63,900 3,633,900
2001 6,910,000 1,770,000 1,200,000 2,970,000 39,500 15,000 54,500 3,024,500
2002 6,140,000 1,220,000 745,000 1,965,000 31,100 7,900 39,000 2,004,000
2003 7,440,000 1,890,000 1,290,000 3,180,000 42,200 16,800 59,000 3,239,000
2004 6,820,000 1,530,000 962,000 2,492,000 37,100 10,700 47,800 2,539,800
2005 8,840,000 3,120,000 2,230,000 5,350,000 62,300 29,800 92,100 5,442,100
2006 7,470,000 2,410,000 1,800,000 4,210,000 47,900 26,900 74,800 4,284,800
2007 6,990,000 1,260,000 719,000 1,979,000 34,400 6,590 40,990 2,019,990
2008 6,460,000 1,210,000 715,000 1,925,000 31,900 7,120 39,020 1,964,020
2009 6,880,000 1,480,000 917,000 2,397,000 36,800 9,980 46,780 2,443,780
2010 7,340,000 1,710,000 1,070,000 2,780,000 41,100 11,900 53,000 2,833,000
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.3 September 2014
Table B.2. Annual Sediment Load for Pre-Project Conditions for Chulitna River near Talkeetna
Chulitna River near Talkeetna -15292400
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1950 5,370,000 3,440,000 1,870,000 5,310,000 328,000 317,000 645,000 5,955,000
1951 6,130,000 4,540,000 2,410,000 6,950,000 374,000 403,000 777,000 7,727,000
1952 5,940,000 5,130,000 2,580,000 7,710,000 363,000 424,000 787,000 8,497,000
1953 6,690,000 4,900,000 2,600,000 7,500,000 408,000 436,000 844,000 8,344,000
1954 6,440,000 5,060,000 2,640,000 7,700,000 393,000 439,000 832,000 8,532,000
1955 6,320,000 5,450,000 2,740,000 8,190,000 386,000 450,000 836,000 9,026,000
1956 7,110,000 6,880,000 3,400,000 10,280,000 434,000 555,000 989,000 11,269,000
1957 6,690,000 5,530,000 2,840,000 8,370,000 408,000 470,000 878,000 9,248,000
1958 6,350,000 5,030,000 2,560,000 7,590,000 387,000 424,000 811,000 8,401,000
1959 6,060,000 5,460,000 2,690,000 8,150,000 370,000 440,000 810,000 8,960,000
1960 6,070,000 4,580,000 2,370,000 6,950,000 371,000 395,000 766,000 7,716,000
1961 6,840,000 6,420,000 3,130,000 9,550,000 418,000 511,000 929,000 10,479,000
1962 6,380,000 5,760,000 2,830,000 8,590,000 390,000 463,000 853,000 9,443,000
1963 5,990,000 5,150,000 2,570,000 7,720,000 365,000 422,000 787,000 8,507,000
1964 6,760,000 9,060,000 3,960,000 13,020,000 413,000 622,000 1,035,000 14,055,000
1965 6,780,000 6,050,000 2,990,000 9,040,000 414,000 490,000 904,000 9,944,000
1966 6,260,000 5,860,000 2,860,000 8,720,000 382,000 466,000 848,000 9,568,000
1967 8,050,000 13,600,000 5,520,000 19,120,000 491,000 848,000 1,339,000 20,459,000
1968 6,660,000 7,430,000 3,460,000 10,890,000 406,000 554,000 960,000 11,850,000
1969 4,420,000 2,600,000 1,410,000 4,010,000 270,000 240,000 510,000 4,520,000
1970 6,320,000 5,580,000 2,770,000 8,350,000 386,000 453,000 839,000 9,189,000
1971 6,090,000 6,500,000 3,010,000 9,510,000 371,000 483,000 854,000 10,364,000
1972 6,050,000 4,750,000 2,430,000 7,180,000 369,000 403,000 772,000 7,952,000
1973 5,490,000 3,760,000 1,990,000 5,750,000 335,000 333,000 668,000 6,418,000
1974 5,730,000 3,780,000 2,040,000 5,820,000 349,000 345,000 694,000 6,514,000
1975 6,490,000 5,490,000 2,780,000 8,270,000 396,000 458,000 854,000 9,124,000
1976 5,510,000 3,810,000 2,020,000 5,830,000 336,000 339,000 675,000 6,505,000
1977 6,330,000 5,440,000 2,740,000 8,180,000 386,000 450,000 836,000 9,016,000
1978 5,540,000 3,480,000 1,890,000 5,370,000 338,000 320,000 658,000 6,028,000
1979 6,470,000 5,410,000 2,740,000 8,150,000 395,000 453,000 848,000 8,998,000
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.4 September 2014
Chulitna River near Talkeetna -15292400
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1980 7,010,000 7,520,000 3,460,000 10,980,000 428,000 555,000 983,000 11,963,000
1981 7,540,000 9,560,000 4,210,000 13,770,000 460,000 665,000 1,125,000 14,895,000
1982 6,120,000 5,210,000 2,600,000 7,810,000 374,000 428,000 802,000 8,612,000
1983 5,950,000 4,480,000 2,300,000 6,780,000 363,000 382,000 745,000 7,525,000
1984 6,140,000 4,280,000 2,250,000 6,530,000 375,000 377,000 752,000 7,282,000
1985 6,120,000 5,020,000 2,530,000 7,550,000 374,000 417,000 791,000 8,341,000
1986 5,410,000 3,510,000 1,890,000 5,400,000 330,000 319,000 649,000 6,049,000
1987 7,140,000 6,140,000 3,030,000 9,170,000 436,000 498,000 934,000 10,104,000
1988 5,860,000 3,880,000 2,100,000 5,980,000 358,000 354,000 712,000 6,692,000
1989 6,480,000 5,280,000 2,710,000 7,990,000 396,000 448,000 844,000 8,834,000
1990 7,920,000 7,140,000 3,530,000 10,670,000 484,000 579,000 1,063,000 11,733,000
1991 5,750,000 4,270,000 2,220,000 6,490,000 351,000 369,000 720,000 7,210,000
1992 5,450,000 4,150,000 2,150,000 6,300,000 333,000 357,000 690,000 6,990,000
1993 7,250,000 6,660,000 3,320,000 9,980,000 442,000 543,000 985,000 10,965,000
1994 6,640,000 4,990,000 2,590,000 7,580,000 405,000 432,000 837,000 8,417,000
1995 6,290,000 4,600,000 2,430,000 7,030,000 384,000 407,000 791,000 7,821,000
1996 4,930,000 2,420,000 1,400,000 3,820,000 301,000 244,000 545,000 4,365,000
1997 5,550,000 3,930,000 2,070,000 6,000,000 339,000 347,000 686,000 6,686,000
1998 5,960,000 4,730,000 2,440,000 7,170,000 364,000 405,000 769,000 7,939,000
1999 5,850,000 4,330,000 2,240,000 6,570,000 357,000 373,000 730,000 7,300,000
2000 6,460,000 5,740,000 2,830,000 8,570,000 394,000 462,000 856,000 9,426,000
2001 5,680,000 3,920,000 2,070,000 5,990,000 347,000 347,000 694,000 6,684,000
2002 5,860,000 4,210,000 2,220,000 6,430,000 358,000 372,000 730,000 7,160,000
2003 6,580,000 4,620,000 2,450,000 7,070,000 401,000 411,000 812,000 7,882,000
2004 5,730,000 3,380,000 1,890,000 5,270,000 350,000 323,000 673,000 5,943,000
2005 8,470,000 9,020,000 4,340,000 13,360,000 517,000 701,000 1,218,000 14,578,000
2006 6,000,000 4,820,000 2,420,000 7,240,000 366,000 400,000 766,000 8,006,000
2007 5,670,000 3,200,000 1,810,000 5,010,000 346,000 311,000 657,000 5,667,000
2008 5,410,000 3,140,000 1,760,000 4,900,000 330,000 300,000 630,000 5,530,000
2009 5,600,000 3,160,000 1,790,000 4,950,000 342,000 306,000 648,000 5,598,000
2010 5,920,000 3,630,000 2,000,000 5,630,000 361,000 340,000 701,000 6,331,000
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.5 September 2014
Table B.3. Annual Sediment Load for Pre-Project Conditions for Talkeetna River near Talkeetna
Talkeetna River near Talkeetna -15292700
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1950 2,460,000 467,000 469,000 936,000 101,000 20,800 121,800 1,057,800
1951 2,800,000 641,000 622,000 1,263,000 117,000 28,900 145,900 1,408,900
1952 2,930,000 1,020,000 867,000 1,887,000 123,000 48,400 171,400 2,058,400
1953 3,080,000 732,000 699,000 1,431,000 129,000 33,200 162,200 1,593,200
1954 2,960,000 747,000 702,000 1,449,000 124,000 34,100 158,100 1,607,100
1955 3,130,000 1,150,000 956,000 2,106,000 132,000 55,200 187,200 2,293,200
1956 3,540,000 1,430,000 1,190,000 2,620,000 151,000 68,800 219,800 2,839,800
1957 3,160,000 920,000 829,000 1,749,000 133,000 42,800 175,800 1,924,800
1958 2,870,000 652,000 621,000 1,273,000 119,000 29,600 148,600 1,421,600
1959 2,950,000 838,000 761,000 1,599,000 124,000 38,800 162,800 1,761,800
1960 2,840,000 617,000 600,000 1,217,000 118,000 27,800 145,800 1,362,800
1961 3,150,000 801,000 749,000 1,550,000 132,000 36,700 168,700 1,718,700
1962 3,160,000 1,030,000 891,000 1,921,000 133,000 48,600 181,600 2,102,600
1963 3,000,000 879,000 791,000 1,670,000 126,000 40,900 166,900 1,836,900
1964 2,870,000 1,220,000 960,000 2,180,000 121,000 59,900 180,900 2,360,900
1965 3,440,000 1,320,000 1,090,000 2,410,000 146,000 63,300 209,300 2,619,300
1966 3,060,000 1,120,000 918,000 2,038,000 128,000 54,300 182,300 2,220,300
1967 3,240,000 1,650,000 1,210,000 2,860,000 137,000 82,500 219,500 3,079,500
1968 3,240,000 1,170,000 976,000 2,146,000 136,000 55,900 191,900 2,337,900
1969 1,630,000 164,000 189,000 353,000 63,500 6,870 70,370 423,370
1970 2,530,000 583,000 553,000 1,136,000 105,000 26,600 131,600 1,267,600
1971 3,840,000 4,070,000 2,400,000 6,470,000 165,000 215,000 380,000 6,850,000
1972 3,250,000 1,150,000 970,000 2,120,000 137,000 54,600 191,600 2,311,600
1973 2,790,000 851,000 716,000 1,567,000 115,000 40,700 155,700 1,722,700
1974 2,410,000 453,000 449,000 902,000 98,400 20,200 118,600 1,020,600
1975 3,140,000 1,040,000 908,000 1,948,000 132,000 49,100 181,100 2,129,100
1976 2,470,000 535,000 510,000 1,045,000 101,000 24,300 125,300 1,170,300
1977 3,150,000 1,430,000 1,100,000 2,530,000 133,000 70,400 203,400 2,733,400
1978 2,390,000 432,000 432,000 864,000 97,300 19,200 116,500 980,500
1979 3,220,000 1,380,000 1,090,000 2,470,000 136,000 67,300 203,300 2,673,300
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.6 September 2014
Talkeetna River near Talkeetna -15292700
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1980 3,150,000 1,030,000 870,000 1,900,000 132,000 49,300 181,300 2,081,300
1981 3,200,000 1,840,000 1,290,000 3,130,000 135,000 93,500 228,500 3,358,500
1982 3,040,000 1,140,000 930,000 2,070,000 128,000 54,900 182,900 2,252,900
1983 2,630,000 486,000 488,000 974,000 108,000 21,600 129,600 1,103,600
1984 2,640,000 619,000 570,000 1,189,000 109,000 28,600 137,600 1,326,600
1985 3,080,000 1,070,000 907,000 1,977,000 130,000 51,000 181,000 2,158,000
1986 2,430,000 433,000 440,000 873,000 99,400 19,200 118,600 991,600
1987 3,480,000 2,070,000 1,320,000 3,390,000 147,000 107,000 254,000 3,644,000
1988 2,710,000 555,000 548,000 1,103,000 112,000 24,900 136,900 1,239,900
1989 3,070,000 894,000 802,000 1,696,000 129,000 41,600 170,600 1,866,600
1990 3,900,000 1,580,000 1,270,000 2,850,000 166,000 77,000 243,000 3,093,000
1991 2,740,000 737,000 668,000 1,405,000 114,000 34,200 148,200 1,553,200
1992 2,560,000 662,000 611,000 1,273,000 106,000 30,500 136,500 1,409,500
1993 3,500,000 1,270,000 1,080,000 2,350,000 149,000 60,400 209,400 2,559,400
1994 3,140,000 880,000 784,000 1,664,000 131,000 41,100 172,100 1,836,100
1995 2,920,000 712,000 673,000 1,385,000 122,000 32,500 154,500 1,539,500
1996 2,260,000 324,000 349,000 673,000 91,600 13,900 105,500 778,500
1997 2,590,000 611,000 576,000 1,187,000 107,000 27,900 134,900 1,321,900
1998 2,790,000 787,000 711,000 1,498,000 117,000 36,500 153,500 1,651,500
1999 2,790,000 814,000 707,000 1,521,000 116,000 38,500 154,500 1,675,500
2000 3,230,000 1,280,000 1,040,000 2,320,000 136,000 61,700 197,700 2,517,700
2001 2,680,000 631,000 591,000 1,222,000 111,000 28,900 139,900 1,361,900
2002 2,750,000 710,000 652,000 1,362,000 115,000 32,800 147,800 1,509,800
2003 3,080,000 773,000 709,000 1,482,000 128,000 35,700 163,700 1,645,700
2004 2,620,000 446,000 465,000 911,000 107,000 19,500 126,500 1,037,500
2005 4,240,000 1,990,000 1,590,000 3,580,000 183,000 97,000 280,000 3,860,000
2006 2,910,000 1,300,000 941,000 2,241,000 121,000 65,000 186,000 2,427,000
2007 2,600,000 445,000 461,000 906,000 107,000 19,500 126,500 1,032,500
2008 2,490,000 441,000 451,000 892,000 102,000 19,400 121,400 1,013,400
2009 2,580,000 438,000 455,000 893,000 106,000 19,200 125,200 1,018,200
2010 2,730,000 506,000 512,000 1,018,000 112,000 22,400 134,400 1,152,400
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.7 September 2014
Table B.4. Annual Sediment Load for Pre-Project Conditions for Susitna River at Sunshine
Susitna River at Sunshine -15292780
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1950 14,200,000 5,860,000 3,770,000 9,630,000 263,000 184,000 447,000 10,077,000
1951 16,200,000 7,860,000 4,890,000 12,750,000 276,000 221,000 497,000 13,247,000
1952 16,700,000 10,600,000 5,990,000 16,590,000 279,000 234,000 513,000 17,103,000
1953 17,900,000 8,720,000 5,400,000 14,120,000 302,000 244,000 546,000 14,666,000
1954 17,200,000 8,880,000 5,400,000 14,280,000 290,000 237,000 527,000 14,807,000
1955 17,800,000 11,400,000 6,440,000 17,840,000 296,000 250,000 546,000 18,386,000
1956 20,000,000 14,500,000 8,070,000 22,570,000 303,000 297,000 600,000 23,170,000
1957 18,300,000 10,300,000 6,100,000 16,400,000 305,000 255,000 560,000 16,960,000
1958 16,600,000 8,230,000 4,960,000 13,190,000 298,000 221,000 519,000 13,709,000
1959 18,400,000 12,500,000 6,970,000 19,470,000 296,000 265,000 561,000 20,031,000
1960 17,100,000 8,330,000 5,100,000 13,430,000 299,000 230,000 529,000 13,959,000
1961 19,000,000 10,400,000 6,140,000 16,540,000 323,000 261,000 584,000 17,124,000
1962 19,900,000 15,600,000 8,230,000 23,830,000 314,000 290,000 604,000 24,434,000
1963 19,300,000 13,400,000 7,460,000 20,860,000 305,000 279,000 584,000 21,444,000
1964 16,400,000 13,800,000 7,040,000 20,840,000 266,000 237,000 503,000 21,343,000
1965 18,700,000 11,200,000 6,540,000 17,740,000 304,000 264,000 568,000 18,308,000
1966 17,100,000 9,660,000 5,610,000 15,270,000 295,000 234,000 529,000 15,799,000
1967 19,400,000 14,100,000 7,750,000 21,850,000 304,000 284,000 588,000 22,438,000
1968 17,800,000 10,700,000 6,120,000 16,820,000 305,000 246,000 551,000 17,371,000
1969 10,100,000 2,580,000 1,860,000 4,440,000 227,000 114,000 341,000 4,781,000
1970 14,300,000 6,260,000 3,970,000 10,230,000 260,000 188,000 448,000 10,678,000
1971 18,400,000 14,700,000 7,670,000 22,370,000 296,000 265,000 561,000 22,931,000
1972 19,200,000 11,800,000 6,710,000 18,510,000 319,000 268,000 587,000 19,097,000
1973 15,100,000 7,330,000 4,420,000 11,750,000 277,000 198,000 475,000 12,225,000
1974 14,100,000 5,760,000 3,720,000 9,480,000 264,000 183,000 447,000 9,927,000
1975 18,400,000 11,200,000 6,490,000 17,690,000 301,000 260,000 561,000 18,251,000
1976 14,900,000 6,380,000 4,040,000 10,420,000 274,000 194,000 468,000 10,888,000
1977 17,900,000 11,300,000 6,370,000 17,670,000 301,000 250,000 551,000 18,221,000
1978 14,800,000 5,160,000 3,450,000 8,610,000 288,000 183,000 471,000 9,081,000
1979 17,400,000 9,920,000 5,790,000 15,710,000 297,000 239,000 536,000 16,246,000
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.8 September 2014
Susitna River at Sunshine -15292780
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1980 18,900,000 11,100,000 6,410,000 17,510,000 318,000 262,000 580,000 18,090,000
1981 20,500,000 15,900,000 8,380,000 24,280,000 325,000 296,000 621,000 24,901,000
1982 17,400,000 8,910,000 5,380,000 14,290,000 301,000 236,000 537,000 14,827,000
1983 17,100,000 8,050,000 4,950,000 13,000,000 304,000 226,000 530,000 13,530,000
1984 17,100,000 8,180,000 4,980,000 13,160,000 307,000 225,000 532,000 13,692,000
1985 17,600,000 9,970,000 5,830,000 15,800,000 301,000 242,000 543,000 16,343,000
1986 14,900,000 5,610,000 3,710,000 9,320,000 282,000 190,000 472,000 9,792,000
1987 19,400,000 10,500,000 6,240,000 16,740,000 324,000 266,000 590,000 17,330,000
1988 18,000,000 9,610,000 5,770,000 15,380,000 306,000 248,000 554,000 15,934,000
1989 18,500,000 9,300,000 5,680,000 14,980,000 316,000 252,000 568,000 15,548,000
1990 23,000,000 15,500,000 8,740,000 24,240,000 353,000 334,000 687,000 24,927,000
1991 15,600,000 6,980,000 4,360,000 11,340,000 288,000 204,000 492,000 11,832,000
1992 15,700,000 7,620,000 4,650,000 12,270,000 285,000 208,000 493,000 12,763,000
1993 18,800,000 10,000,000 6,050,000 16,050,000 316,000 260,000 576,000 16,626,000
1994 18,200,000 8,990,000 5,440,000 14,430,000 317,000 243,000 560,000 14,990,000
1995 18,400,000 9,430,000 5,730,000 15,160,000 313,000 251,000 564,000 15,724,000
1996 12,800,000 3,760,000 2,650,000 6,410,000 263,000 153,000 416,000 6,826,000
1997 16,800,000 8,570,000 5,180,000 13,750,000 294,000 226,000 520,000 14,270,000
1998 17,800,000 10,100,000 5,980,000 16,080,000 298,000 248,000 546,000 16,626,000
1999 17,600,000 9,320,000 5,550,000 14,870,000 305,000 239,000 544,000 15,414,000
2000 19,300,000 11,900,000 6,790,000 18,690,000 320,000 270,000 590,000 19,280,000
2001 17,200,000 8,790,000 5,270,000 14,060,000 304,000 231,000 535,000 14,595,000
2002 15,700,000 7,020,000 4,410,000 11,430,000 284,000 207,000 491,000 11,921,000
2003 18,600,000 9,520,000 5,710,000 15,230,000 319,000 251,000 570,000 15,800,000
2004 16,900,000 7,890,000 4,920,000 12,810,000 299,000 226,000 525,000 13,335,000
2005 22,400,000 15,900,000 8,940,000 24,840,000 333,000 332,000 665,000 25,505,000
2006 18,100,000 10,900,000 6,270,000 17,170,000 301,000 252,000 553,000 17,723,000
2007 17,200,000 6,810,000 4,460,000 11,270,000 310,000 224,000 534,000 11,804,000
2008 16,000,000 6,620,000 4,240,000 10,860,000 294,000 207,000 501,000 11,361,000
2009 16,900,000 7,530,000 4,770,000 12,300,000 299,000 225,000 524,000 12,824,000
2010 18,000,000 8,540,000 5,310,000 13,850,000 310,000 243,000 553,000 14,403,000
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.9 September 2014
Table B.5. Annual Sediment Load for Pre-Project Conditions for Yentna River near Susitna Station
Yentna River near Susitna Station -15294345
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1950 11,800,000 4,700,000 4,140,000 8,840,000 2,020,000 184,000 2,204,000 11,044,000
1951 13,400,000 6,080,000 4,970,000 11,050,000 2,030,000 192,000 2,222,000 13,272,000
1952 13,300,000 6,920,000 5,060,000 11,980,000 2,060,000 180,000 2,240,000 14,220,000
1953 14,800,000 6,640,000 5,460,000 12,100,000 2,140,000 208,000 2,348,000 14,448,000
1954 14,200,000 6,680,000 5,290,000 11,970,000 2,100,000 195,000 2,295,000 14,265,000
1955 14,300,000 7,420,000 5,410,000 12,830,000 2,140,000 182,000 2,322,000 15,152,000
1956 15,800,000 9,240,000 6,350,000 15,590,000 2,090,000 193,000 2,283,000 17,873,000
1957 14,900,000 7,400,000 5,640,000 13,040,000 2,170,000 190,000 2,360,000 15,400,000
1958 13,700,000 6,000,000 4,890,000 10,890,000 2,180,000 188,000 2,368,000 13,258,000
1959 14,800,000 8,120,000 5,760,000 13,880,000 2,110,000 186,000 2,296,000 16,176,000
1960 13,000,000 5,400,000 4,580,000 9,980,000 2,150,000 188,000 2,338,000 12,318,000
1961 14,700,000 7,020,000 5,410,000 12,430,000 2,230,000 197,000 2,427,000 14,857,000
1962 11,600,000 3,960,000 3,820,000 7,780,000 2,130,000 181,000 2,311,000 10,091,000
1963 11,900,000 5,410,000 4,260,000 9,670,000 2,050,000 180,000 2,230,000 11,900,000
1964 12,700,000 7,440,000 4,900,000 12,340,000 2,040,000 171,000 2,211,000 14,551,000
1965 13,400,000 6,550,000 4,970,000 11,520,000 2,120,000 188,000 2,308,000 13,828,000
1966 13,000,000 6,490,000 4,760,000 11,250,000 2,150,000 184,000 2,334,000 13,584,000
1967 11,400,000 4,510,000 3,960,000 8,470,000 2,020,000 181,000 2,201,000 10,671,000
1968 13,100,000 6,400,000 4,810,000 11,210,000 2,140,000 174,000 2,314,000 13,524,000
1969 10,600,000 4,690,000 3,720,000 8,410,000 1,960,000 159,000 2,119,000 10,529,000
1970 14,700,000 8,250,000 5,720,000 13,970,000 2,100,000 191,000 2,291,000 16,261,000
1971 14,000,000 10,200,000 5,760,000 15,960,000 2,060,000 166,000 2,226,000 18,186,000
1972 12,200,000 5,180,000 4,310,000 9,490,000 2,090,000 184,000 2,274,000 11,764,000
1973 10,700,000 3,530,000 3,450,000 6,980,000 2,070,000 183,000 2,253,000 9,233,000
1974 10,500,000 2,940,000 3,270,000 6,210,000 2,100,000 184,000 2,284,000 8,494,000
1975 13,700,000 6,730,000 5,090,000 11,820,000 2,130,000 185,000 2,315,000 14,135,000
1976 12,500,000 4,690,000 4,280,000 8,970,000 2,140,000 194,000 2,334,000 11,304,000
1977 19,000,000 14,400,000 8,060,000 22,460,000 2,310,000 195,000 2,505,000 24,965,000
1978 12,900,000 4,950,000 4,430,000 9,380,000 2,170,000 198,000 2,368,000 11,748,000
1979 15,000,000 7,130,000 5,550,000 12,680,000 2,220,000 199,000 2,419,000 15,099,000
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.10 September 2014
Yentna River near Susitna Station -15294345
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1980 18,900,000 12,500,000 7,670,000 20,170,000 2,360,000 216,000 2,576,000 22,746,000
1981 18,000,000 11,400,000 7,270,000 18,670,000 2,300,000 208,000 2,508,000 21,178,000
1982 13,500,000 6,230,000 4,880,000 11,110,000 2,160,000 187,000 2,347,000 13,457,000
1983 13,300,000 5,980,000 4,720,000 10,700,000 2,190,000 187,000 2,377,000 13,077,000
1984 14,500,000 7,190,000 5,400,000 12,590,000 2,190,000 194,000 2,384,000 14,974,000
1985 14,200,000 7,190,000 5,370,000 12,560,000 2,140,000 190,000 2,330,000 14,890,000
1986 14,200,000 6,430,000 5,190,000 11,620,000 2,180,000 202,000 2,382,000 14,002,000
1987 17,100,000 10,400,000 6,780,000 17,180,000 2,260,000 208,000 2,468,000 19,648,000
1988 16,600,000 8,890,000 6,360,000 15,250,000 2,300,000 197,000 2,497,000 17,747,000
1989 17,700,000 11,000,000 7,170,000 18,170,000 2,230,000 205,000 2,435,000 20,605,000
1990 19,100,000 11,600,000 7,700,000 19,300,000 2,330,000 217,000 2,547,000 21,847,000
1991 14,900,000 7,840,000 5,680,000 13,520,000 2,180,000 191,000 2,371,000 15,891,000
1992 13,300,000 5,400,000 4,620,000 10,020,000 2,240,000 184,000 2,424,000 12,444,000
1993 14,800,000 6,700,000 5,410,000 12,110,000 2,220,000 194,000 2,414,000 14,524,000
1994 14,300,000 6,130,000 5,110,000 11,240,000 2,240,000 201,000 2,441,000 13,681,000
1995 14,900,000 6,870,000 5,490,000 12,360,000 2,220,000 195,000 2,415,000 14,775,000
1996 10,000,000 2,860,000 3,140,000 6,000,000 2,030,000 182,000 2,212,000 8,212,000
1997 13,400,000 6,010,000 4,850,000 10,860,000 2,140,000 184,000 2,324,000 13,184,000
1998 14,100,000 6,950,000 5,310,000 12,260,000 2,120,000 183,000 2,303,000 14,563,000
1999 14,100,000 6,460,000 5,150,000 11,610,000 2,180,000 196,000 2,376,000 13,986,000
2000 15,300,000 7,830,000 5,780,000 13,610,000 2,220,000 200,000 2,420,000 16,030,000
2001 13,900,000 6,310,000 5,030,000 11,340,000 2,190,000 191,000 2,381,000 13,721,000
2002 12,400,000 4,960,000 4,330,000 9,290,000 2,110,000 183,000 2,293,000 11,583,000
2003 14,700,000 6,660,000 5,340,000 12,000,000 2,230,000 200,000 2,430,000 14,430,000
2004 13,700,000 6,050,000 4,980,000 11,030,000 2,150,000 188,000 2,338,000 13,368,000
2005 17,100,000 10,100,000 6,920,000 17,020,000 2,160,000 197,000 2,357,000 19,377,000
2006 14,500,000 7,510,000 5,530,000 13,040,000 2,130,000 195,000 2,325,000 15,365,000
2007 14,300,000 5,630,000 5,030,000 10,660,000 2,240,000 207,000 2,447,000 13,107,000
2008 13,100,000 5,100,000 4,550,000 9,650,000 2,170,000 192,000 2,362,000 12,012,000
2009 13,900,000 5,950,000 5,020,000 10,970,000 2,140,000 203,000 2,343,000 13,313,000
2010 14,800,000 6,780,000 5,480,000 12,260,000 2,180,000 200,000 2,380,000 14,640,000
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.11 September 2014
Table B.6. Annual Sediment Load for Pre-Project Conditions for Susitna River at Susitna Station
Susitna River at Susitna Station -15294350
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1950 30,700,000 14,200,000 10,500,000 24,700,000 1,180,000 139,000 1,319,000 26,019,000
1951 34,300,000 18,200,000 12,500,000 30,700,000 1,290,000 165,000 1,455,000 32,155,000
1952 34,000,000 21,000,000 12,900,000 33,900,000 1,270,000 169,000 1,439,000 35,339,000
1953 37,800,000 20,000,000 13,800,000 33,800,000 1,420,000 182,000 1,602,000 35,402,000
1954 36,000,000 20,000,000 13,300,000 33,300,000 1,350,000 176,000 1,526,000 34,826,000
1955 36,400,000 22,600,000 13,800,000 36,400,000 1,360,000 181,000 1,541,000 37,941,000
1956 40,100,000 28,000,000 16,200,000 44,200,000 1,470,000 212,000 1,682,000 45,882,000
1957 37,800,000 22,200,000 14,200,000 36,400,000 1,420,000 187,000 1,607,000 38,007,000
1958 35,200,000 18,000,000 12,400,000 30,400,000 1,350,000 163,000 1,513,000 31,913,000
1959 37,400,000 24,500,000 14,600,000 39,100,000 1,390,000 192,000 1,582,000 40,682,000
1960 34,600,000 17,700,000 12,400,000 30,100,000 1,320,000 163,000 1,483,000 31,583,000
1961 37,800,000 20,900,000 13,900,000 34,800,000 1,430,000 183,000 1,613,000 36,413,000
1962 34,700,000 19,600,000 12,700,000 32,300,000 1,310,000 167,000 1,477,000 33,777,000
1963 34,100,000 19,700,000 12,700,000 32,400,000 1,280,000 166,000 1,446,000 33,846,000
1964 31,000,000 18,200,000 11,500,000 29,700,000 1,170,000 150,000 1,320,000 31,020,000
1965 35,700,000 20,500,000 13,200,000 33,700,000 1,340,000 174,000 1,514,000 35,214,000
1966 33,500,000 18,000,000 12,100,000 30,100,000 1,270,000 159,000 1,429,000 31,529,000
1967 32,700,000 17,700,000 11,900,000 29,600,000 1,240,000 156,000 1,396,000 30,996,000
1968 34,000,000 19,100,000 12,400,000 31,500,000 1,290,000 162,000 1,452,000 32,952,000
1969 24,200,000 9,620,000 7,670,000 17,290,000 955,000 101,000 1,056,000 18,346,000
1970 33,800,000 18,300,000 12,300,000 30,600,000 1,270,000 162,000 1,432,000 32,032,000
1971 34,600,000 22,800,000 13,300,000 36,100,000 1,290,000 175,000 1,465,000 37,565,000
1972 33,900,000 18,500,000 12,300,000 30,800,000 1,280,000 162,000 1,442,000 32,242,000
1973 29,900,000 13,100,000 9,920,000 23,020,000 1,170,000 131,000 1,301,000 24,321,000
1974 29,000,000 11,600,000 9,410,000 21,010,000 1,130,000 124,000 1,254,000 22,264,000
1975 33,400,000 18,700,000 12,200,000 30,900,000 1,260,000 161,000 1,421,000 32,321,000
1976 31,200,000 14,500,000 10,700,000 25,200,000 1,200,000 141,000 1,341,000 26,541,000
1977 40,500,000 28,400,000 16,100,000 44,500,000 1,490,000 211,000 1,701,000 46,201,000
1978 30,400,000 13,100,000 10,100,000 23,200,000 1,180,000 133,000 1,313,000 24,513,000
1979 38,900,000 23,500,000 14,700,000 38,200,000 1,450,000 194,000 1,644,000 39,844,000
APPENDIX B SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page B.12 September 2014
Susitna River at Susitna Station -15294350
WY Water Volume
(acre-ft)
Suspended Load Bed Load
Total Load
Silt/Clay Sand Total Sand Gravel Total
1980 45,000,000 32,200,000 17,900,000 50,100,000 1,650,000 235,000 1,885,000 51,985,000
1981 40,300,000 28,900,000 16,000,000 44,900,000 1,490,000 210,000 1,700,000 46,600,000
1982 34,100,000 17,600,000 12,100,000 29,700,000 1,300,000 159,000 1,459,000 31,159,000
1983 31,700,000 14,200,000 10,600,000 24,800,000 1,230,000 140,000 1,370,000 26,170,000
1984 32,900,000 14,600,000 11,100,000 25,700,000 1,280,000 146,000 1,426,000 27,126,000
1985 34,200,000 19,200,000 12,600,000 31,800,000 1,290,000 165,000 1,455,000 33,255,000
1986 33,600,000 15,200,000 11,400,000 26,600,000 1,290,000 150,000 1,440,000 28,040,000
1987 39,700,000 25,500,000 15,200,000 40,700,000 1,480,000 200,000 1,680,000 42,380,000
1988 38,900,000 22,100,000 14,300,000 36,400,000 1,470,000 188,000 1,658,000 38,058,000
1989 40,900,000 27,100,000 16,100,000 43,200,000 1,510,000 211,000 1,721,000 44,921,000
1990 44,300,000 28,500,000 17,300,000 45,800,000 1,640,000 227,000 1,867,000 47,667,000
1991 34,900,000 19,600,000 12,800,000 32,400,000 1,320,000 168,000 1,488,000 33,888,000
1992 31,900,000 13,800,000 10,500,000 24,300,000 1,240,000 138,000 1,378,000 25,678,000
1993 38,500,000 22,200,000 14,400,000 36,600,000 1,440,000 190,000 1,630,000 38,230,000
1994 37,500,000 19,300,000 13,400,000 32,700,000 1,430,000 176,000 1,606,000 34,306,000
1995 37,200,000 20,000,000 13,600,000 33,600,000 1,400,000 179,000 1,579,000 35,179,000
1996 27,800,000 9,820,000 8,630,000 18,450,000 1,100,000 114,000 1,214,000 19,664,000
1997 32,300,000 16,600,000 11,400,000 28,000,000 1,230,000 150,000 1,380,000 29,380,000
1998 34,100,000 19,400,000 12,700,000 32,100,000 1,280,000 167,000 1,447,000 33,547,000
1999 33,700,000 17,500,000 12,000,000 29,500,000 1,290,000 158,000 1,448,000 30,948,000
2000 36,500,000 21,100,000 13,500,000 34,600,000 1,380,000 177,000 1,557,000 36,157,000
2001 34,000,000 17,600,000 12,000,000 29,600,000 1,300,000 158,000 1,458,000 31,058,000
2002 32,700,000 16,000,000 11,500,000 27,500,000 1,250,000 151,000 1,401,000 28,901,000
2003 38,000,000 19,700,000 13,600,000 33,300,000 1,440,000 179,000 1,619,000 34,919,000
2004 34,700,000 17,000,000 12,200,000 29,200,000 1,320,000 161,000 1,481,000 30,681,000
2005 44,400,000 31,000,000 18,000,000 49,000,000 1,620,000 237,000 1,857,000 50,857,000
2006 35,800,000 20,700,000 13,300,000 34,000,000 1,350,000 175,000 1,525,000 35,525,000
2007 35,100,000 15,500,000 12,000,000 27,500,000 1,350,000 158,000 1,508,000 29,008,000
2008 32,900,000 14,900,000 11,200,000 26,100,000 1,270,000 148,000 1,418,000 27,518,000
2009 34,500,000 16,300,000 12,000,000 28,300,000 1,320,000 159,000 1,479,000 29,779,000
2010 36,400,000 18,100,000 12,900,000 31,000,000 1,390,000 170,000 1,560,000 32,560,000
APPENDIX C. SEDIMENT TRANSPORT RATING CURVES DATA
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Geomorphology Study (Study 6.5)
2014 Update of Sediment-Transport Relationships
and a Revised Sediment Balance for the
Middle and Lower Susitna River Segments
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
Tetra Tech, Inc.
September 2014
APPENDIX C SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page C.1 September 2014
Table C.1. Sediment loads over a range of discharges for Pre-Project Conditions for Susitna River at Gold Creek.
Susitna River at Gold Creek -15292000
Q, (cfs)
Suspended Silt/Clay Suspended Sand Bedload Sand Bedload Gravel
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
5,000 163 201 42 49 13 16 0 0
10,000 1,040 1,320 409 485 46 62 1 2
15,000 3,070 3,950 1,550 1,850 97 134 3 11
20,000 6,620 8,550 3,990 4,780 165 230 12 41
25,000 12,000 15,500 8,320 9,960 249 348 31 109
30,000 19,600 25,200 15,100 18,100 349 486 69 238
40,000 42,200 54,200 39,000 46,500 594 818 241 793
50,000 76,600 97,900 81,200 96,400 896 1,220 634 1,960
60,000 125,000 158,000 148,000 175,000 1,260 1,680 1,400 4,050
70,000 188,000 238,000 245,000 289,000 1,670 2,200 2,740 7,370
80,000 269,000 337,000 381,000 446,000 2,140 2,770 4,890 12,300
90,000 369,000 460,000 561,000 653,000 2,660 3,390 8,150 19,100
100,000 489,000 605,000 793,000 920,000 3,230 4,060 12,900 28,100
APPENDIX C SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page C.2 September 2014
Table C.2. Sediment loads over a range of discharges for Pre-Project Conditions for Chulitna River near Talkeetna.
Chulitna River near Talkeetna -15292400
Q, (cfs)
Suspended Silt/Clay Suspended Sand Bedload Sand Bedload Gravel
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
5,000 825 878 801 856 605 605 180 180
10,000 4,970 5,330 3,570 3,850 1,210 1,210 720 720
15,000 14,200 15,200 8,560 9,250 1,820 1,820 1,620 1,620
20,000 29,900 32,100 15,900 17,200 2,420 2,420 2,880 2,880
25,000 53,300 57,200 25,800 27,800 3,030 3,030 4,500 4,500
30,000 85,400 91,700 38,200 41,200 3,630 3,630 6,480 6,480
40,000 180,000 193,000 71,000 76,500 4,840 4,840 11,500 11,500
50,000 321,000 342,000 115,000 123,000 6,050 6,050 18,000 18,000
60,000 514,000 548,000 170,000 182,000 7,260 7,260 25,900 25,900
70,000 766,000 815,000 237,000 254,000 8,470 8,470 35,300 35,300
80,000 1,080,000 1,150,000 317,000 337,000 9,680 9,680 46,100 46,100
90,000 1,470,000 1,550,000 408,000 434,000 10,900 10,900 58,300 58,300
100,000 1,930,000 2,040,000 512,000 543,000 12,100 12,100 72,000 72,000
APPENDIX C SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page C.3 September 2014
Table C.3. Sediment loads over a range of discharges for Pre-Project Conditions for Talkeetna River near Talkeetna.
Talkeetna River near Talkeetna -15292700
Q, (cfs)
Suspended Silt/Clay Suspended Sand Bedload Sand Bedload Gravel
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
2,000 46 63 116 130 103 143 1 2
5,000 595 835 973 1,100 279 406 23 32
10,000 4,130 5,830 4,870 5,530 589 866 183 264
15,000 12,800 18,000 12,500 14,200 914 1,330 615 880
20,000 28,600 40,000 24,400 27,600 1,250 1,790 1,450 2,040
25,000 53,400 74,200 41,000 46,200 1,590 2,260 2,840 3,890
30,000 88,900 123,000 62,600 70,500 1,930 2,710 4,900 6,560
40,000 199,000 271,000 122,000 137,000 2,640 3,620 11,600 14,900
50,000 370,000 500,000 205,000 229,000 3,360 4,510 22,600 27,800
60,000 616,000 823,000 313,000 349,000 4,090 5,380 39,000 46,200
70,000 948,000 1,250,000 448,000 497,000 4,830 6,250 61,900 70,700
80,000 1,380,000 1,810,000 611,000 676,000 5,590 7,100 92,300 102,000
APPENDIX C SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page C.4 September 2014
Table C.4. Sediment loads over a range of discharges for Pre-Project Conditions for Susitna River at Sunshine.
Susitna River at Sunshine -15292780
Q, (cfs)
Suspended Silt/Clay Suspended Sand Bedload Sand Bedload Gravel
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
5,000 119 129 220 231 389 421 38 49
10,000 691 771 946 1,010 542 620 95 144
15,000 1,930 2,190 2,220 2,390 657 771 163 265
20,000 4,010 4,570 4,070 4,410 754 896 238 403
25,000 7,060 8,080 6,510 7,070 839 1,000 319 554
30,000 11,200 12,900 9,550 10,400 915 1,100 406 715
40,000 23,200 26,800 17,500 19,100 1,050 1,270 593 1,060
50,000 40,900 47,200 28,000 30,500 1,170 1,420 796 1,430
60,000 65,000 74,900 41,100 44,800 1,270 1,540 1,010 1,820
70,000 96,100 111,000 56,900 62,000 1,370 1,660 1,240 2,220
80,000 135,000 155,000 75,300 82,000 1,460 1,770 1,480 2,630
90,000 182,000 209,000 96,500 105,000 1,550 1,860 1,730 3,060
100,000 237,000 272,000 120,000 131,000 1,630 1,960 1,980 3,490
110,000 302,000 346,000 147,000 160,000 1,700 2,040 2,250 3,920
120,000 377,000 431,000 177,000 192,000 1,780 2,120 2,520 4,360
130,000 462,000 527,000 209,000 227,000 1,840 2,200 2,800 4,810
140,000 557,000 636,000 245,000 265,000 1,910 2,270 3,090 5,260
150,000 664,000 756,000 283,000 306,000 1,980 2,340 3,390 5,710
160,000 782,000 889,000 324,000 350,000 2,040 2,410 3,690 6,170
170,000 912,000 1,030,000 368,000 398,000 2,100 2,470 3,990 6,630
180,000 1,050,000 1,190,000 415,000 448,000 2,150 2,540 4,310 7,090
APPENDIX C SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page C.5 September 2014
Table C.5. Sediment loads over a range of discharges for Pre-Project Conditions for Susitna River at Yentna River near
Susitna Station
Yentna River near Susitna Station -15294345
Q, (cfs)
Suspended Silt/Clay Suspended Sand Bedload Sand Bedload Gravel
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
5,000 253 263 1,490 1,530 5,360 5,060 100 100
10,000 1,270 1,350 4,020 4,150 5,960 5,980 200 200
15,000 3,270 3,510 7,170 7,430 6,330 6,520 513 513
20,000 6,400 6,900 10,800 11,200 6,620 6,890 1,000 1,000
25,000 10,800 11,600 14,900 15,500 6,850 7,180 1,000 1,000
30,000 16,500 17,800 19,300 20,100 7,040 7,400 1,000 1,000
40,000 32,200 34,800 29,000 30,300 7,350 7,750 1,000 1,000
50,000 54,100 58,500 39,900 41,600 7,610 8,010 1,000 1,000
60,000 82,700 89,400 51,800 53,900 7,820 8,210 1,000 1,000
70,000 118,000 128,000 64,500 67,100 8,000 8,380 1,000 1,000
80,000 162,000 174,000 78,100 81,100 8,170 8,510 1,000 1,000
90,000 213,000 229,000 92,300 95,900 8,320 8,630 1,000 1,000
100,000 272,000 292,000 107,000 111,000 8,450 8,730 1,000 1,000
110,000 340,000 364,000 123,000 127,000 8,570 8,810 1,000 1,000
120,000 416,000 445,000 139,000 144,000 8,690 8,890 1,000 1,000
130,000 501,000 535,000 156,000 161,000 8,790 8,960 1,000 1,000
140,000 595,000 635,000 173,000 179,000 8,890 9,020 1,000 1,000
150,000 699,000 744,000 191,000 198,000 8,990 9,070 1,000 1,000
160,000 813,000 863,000 210,000 216,000 9,080 9,120 1,000 1,000
170,000 936,000 993,000 229,000 236,000 9,160 9,170 1,000 1,000
180,000 1,070,000 1,130,000 248,000 256,000 9,240 9,210 1,000 1,000
APPENDIX C SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No.14241 Page C.6 September 2014
Table C.6. Sediment loads over a range of discharges for Pre-Project Conditions for Susitna River at Susitna Station
Susitna River at Susitna Station -15294350
Q, (cfs)
Suspended Silt/Clay Suspended Sand Bedload Sand Bedload Gravel
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
Qs,
(tons/day)
Unbiased
Qs,
(tons/day)
5,000 66 67 731 742 557 488 10 7
10,000 354 374 2,090 2,190 994 949 29 25
15,000 947 1,020 3,880 4,120 1,390 1,380 54 50
20,000 1,900 2,060 6,000 6,440 1,770 1,800 83 80
25,000 3,270 3,560 8,420 9,080 2,130 2,200 115 115
30,000 5,080 5,560 11,100 12,000 2,480 2,590 152 155
40,000 10,200 11,200 17,200 18,700 3,160 3,340 233 245
50,000 17,500 19,400 24,100 26,400 3,800 4,060 326 348
60,000 27,300 30,200 31,800 34,800 4,420 4,750 428 463
70,000 39,600 43,900 40,200 44,100 5,030 5,420 539 587
80,000 54,800 60,800 49,200 54,000 5,620 6,070 659 719
90,000 72,900 80,900 58,900 64,600 6,200 6,700 786 860
100,000 94,100 104,000 69,100 75,800 6,770 7,320 920 1,010
110,000 119,000 132,000 79,900 87,700 7,330 7,920 1,060 1,160
120,000 146,000 162,000 91,100 100,000 7,890 8,510 1,210 1,320
130,000 178,000 197,000 103,000 113,000 8,430 9,090 1,360 1,490
140,000 213,000 236,000 115,000 126,000 8,970 9,660 1,520 1,660
150,000 251,000 279,000 128,000 140,000 9,500 10,200 1,690 1,840
160,000 294,000 326,000 141,000 155,000 10,000 10,800 1,860 2,020
170,000 340,000 377,000 155,000 169,000 10,500 11,300 2,040 2,210
180,000 391,000 433,000 169,000 185,000 11,100 11,800 2,220 2,400
190,000 446,000 493,000 183,000 200,000 11,600 12,400 2,410 2,590
200,000 505,000 558,000 198,000 216,000 12,100 12,900 2,600 2,790
210,000 568,000 628,000 213,000 233,000 12,600 13,400 2,800 2,990
220,000 636,000 702,000 229,000 250,000 13,100 13,900 3,000 3,200
230,000 708,000 782,000 245,000 267,000 13,600 14,400 3,210 3,410
240,000 785,000 866,000 261,000 285,000 14,100 14,900 3,420 3,620
250,000 867,000 955,000 278,000 303,000 14,500 15,400 3,630 3,840
260,000 954,000 1,050,000 295,000 321,000 15,000 15,900 3,850 4,060
270,000 1,040,000 1,150,000 312,000 340,000 15,500 16,400 4,080 4,280
280,000 1,140,000 1,250,000 330,000 359,000 16,000 16,800 4,300 4,510
290,000 1,240,000 1,370,000 348,000 378,000 16,500 17,300 4,540 4,730
300,000 1,350,000 1,480,000 366,000 398,000 16,900 17,800 4,770 4,960