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Susitna‐Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
Ice processes in the Susitna River study, Study plan Section 7.6, 2014-
2015 Study Implementation Report. [ Main report ] SuWa 289
Author(s) – Personal:
Author(s) – Corporate:
HDR
AEA‐identified category, if specified:
November 2015; Study Completion and 2014/2015 Implementation Reports
AEA‐identified series, if specified:
Series (ARLIS‐assigned report number):
Susitna-Watana Hydroelectric Project document number 289
Existing numbers on document:
Published by:
[Anchorage : Alaska Energy Authority, 2015]
Date published:
October 2015
Appendix A: September 2015
Published for:
Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers:
Study plan Section 7.6
Final or Draft status, as indicated:
Document type:
Pagination:
iii, 9 pages (main report only)
Related works(s):
See below for list. Be aware that the name of the study at the
beginning of title varies in each part.
Pages added/changed by ARLIS:
Notes:
Accompanying volumes (each appears in a separate electronic file):
Appendix A. Alternative visualizations of freeze-up progression and open leads.
Appendix B. Technical memorandum: River1D model--initial open water calibration and
validation.
Appendix C. River2D open-water modeling report, Focus Area 128 (Slough 8A)
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/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Ice Processes in the Susitna River Study
Study Plan Section 7.6
2014-2015 Study Implementation Report
Prepared for
Alaska Energy Authority
Prepared by
HDR
October 2015
2014-2015 STUDY IMPLEMENTATION REPORT ICE PROCESSES IN THE SUSITNA RIVER (STUDY 7.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i October 2015
TABLE OF CONTENTS
1. Introduction ....................................................................................................................... 1
2. Study Objectives................................................................................................................ 1
3. Study Area ......................................................................................................................... 2
3.1. Observations ........................................................................................................... 2
3.2. Middle River River1D Ice Processes Modeling ..................................................... 3
3.3. Middle River River2D Focus Area Ice Modeling ................................................... 3
3.4. Lower River ............................................................................................................ 3
4. Methods and Variances .................................................................................................... 3
4.1. Aerial Reconnaissance ............................................................................................ 3
4.2. Time-Lapse Camera Monitoring ............................................................................. 4
4.3. Ice Measurement Data ............................................................................................ 4
4.4. Other Field Data ...................................................................................................... 4
4.5. Modeling of River Ice Processes ............................................................................ 4
4.6. Lower River Assessment ........................................................................................ 4
4.7. Review and Compilation of Existing Cold Regions Hydropower Project
Operations and Effects ............................................................................................ 5
5. Results ................................................................................................................................ 5
5.1. Alternate Visualizations of Freeze-up Progression and Open Lead Survey
Information ............................................................................................................. 5
5.2. River1D Middle River Model Development and Initial Open Water Calibration .. 6
5.3. River2D Model Development and Open Water Calibration for Focus Area 128
(Slough 8A) ............................................................................................................. 6
6. Discussion........................................................................................................................... 6
7. Conclusion ......................................................................................................................... 8
8. Literature Cited ................................................................................................................ 9
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APPENDICES
Appendix A: Visualizations of Ice Progression and Open Lead Surveys
Appendix B: Technical Memorandum: River1D Model - Initial Open Water Calibration and
Validation
Appendix C: Technical Memorandum: River2D Modeling Report of Focus Area 128 (Slough 8a)
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LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
AEA Alaska Energy Authority
ESS Alaska Energy Authority station on the Susitna River for Surface water
FA Focus Area (Aquatic Habitat)
FERC Federal Energy Regulatory Commission
GIS Geographic Information System
HDR HDR, Inc.
HEC-RAS Hydrologic Engineering Centers River Analysis System
ILP Integrated Licensing Process
ISR Initial Study Report
PRM Project River Mile
Project Susitna-Watana Hydroelectric Project
R2 R2 Resource Consultants
RM River Mile
RSP Revised Study Plan
SPD Study Plan Determination
USGS U.S. Geological Survey
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1. INTRODUCTION
This Ice Processes in the Susitna River Study, Section 7.6 of the Revised Study Plan (RSP)
approved by the Federal Energy Regulatory Commission (FERC) for the Susitna-Watana
Hydroelectric Project, FERC Project No. 14241, focuses on furthering the understanding of natural
ice processes in the Susitna River and providing a method to model/predict pre-Project and post-
Project ice processes in the Susitna River.
A summary of the development of this study, together with the Alaska Energy Authority’s (AEA)
implementation of it through the 2013 study season, appears in Part A, Section 1 of the Initial
Study Report (ISR) filed with FERC in June 2014. As required under FERC’s regulations for the
Integrated Licensing Process (ILP), the ISR describes AEA’s “overall progress in implementing
the study plan and schedule and the data collected, including an explanation of any variance from
the study plan and schedule.” (18 CFR 5.15(c)(1)).
Since filing the ISR in June 2014, AEA has continued to implement the FERC-approved plan for
the Ice Processes in the Susitna River Study. For example:
The River1D ice processes model of the Middle River reach (PRM 100.7-187.2) and
River2D models of the Focus Areas have continued to be developed and calibrated for open
water conditions.
A technical Memorandum describing detailed ice observations from October 2013-May
2014 was filed in September 2014.
On October 17, 2014, AEA held an ISR meeting for the Ice Processes in the Susitna River
Study.
In furtherance of the next round of ISR meetings and FERC’s SPD expected in 2016, this report
describes AEA’s overall progress in implementing the Ice Processes in the Susitna River Study
(Study 7.6) during calendar year 2014. Rather than a comprehensive reporting of all field work,
data collection, and data analysis since the beginning of AEA’s study program, this report is
intended to supplement and update the information presented in Part A of the ISR for the Ice
Processes in the Susitna River Study through the end of calendar year 2014. It describes the
methods and results of the 2014 effort, and includes a discussion of the results achieved.
2. STUDY OBJECTIVES
The Ice Processes in the Susitna River Study (Study 7.6) will further the understanding of natural
ice processes in the Susitna River and provide a method to model/predict pre-Project and post-
Project ice processes in the Susitna River. The study will provide a basis for impact assessment,
which will inform the development of any necessary protection, mitigation, and enhancement
measures. The study also will provide ice processes input data for other resource studies with
winter components (e.g., Fluvial Geomorphology Modeling below Watana Dam Study [Study
6.6], Instream Flow Studies [Studies 8.5-8.6], Instream Flow Riparian [ISR Study 8.6], and
Groundwater Study [Study 7.5]).
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The overall goals of the Ice Processes in the Susitna River Study (Study 7.6) are to understand
existing ice processes in the Susitna River and to predict post-Project ice processes. The specific
objectives are as follows:
Document the timing, progression, and physical processes of freeze-up and break-up
during 2012–2014 between tidewater and the Oshetna River confluence (PRM 235.2 [RM
233.4]), using historical data, aerial reconnaissance, stationary time-lapse cameras, and
physical evidence.
Determine the potential effect of various Project operational scenarios on ice processes
downstream of Watana Dam using modeling and analytical methods.
o Develop a modeling approach for quantitatively assessing ice processes in the
Susitna River.
o Calibrate the model based on existing conditions. Use the model to determine the
extent of the open water reach downstream of Watana Dam during Project
operations.
o Use the model to determine the changes in timing and ice-cover progression and
ice thickness and extent during Project operations.
Develop detailed models and characterizations of ice processes at instream flow Focus
Areas in order to provide physical data on winter habitat for the Fish and Aquatics Instream
Flow Study (Study 8.5).
Provide observational data of existing ice processes and modeling results of post-Project
ice processes to the Fluvial Geomorphology Modeling below Watana Dam Study (Study
6.6), Groundwater Study (7.5), Instream Flow Studies (Studies 8.5-8.6), Fish and Aquatics
Study (Studies 9.12), Riparian Vegetation Study Downstream of the Proposed Susitna-
Watana Dam (Study 11.6), Recreation and Aesthetics Studies (12.5-12.7), and
Socioeconomic and Transportation Study (Study 15.7).
Research and summarize large river ice processes relevant to the Susitna River, analytical
methods that have been used to assess impacts of projects on ice-covered rivers, and the
known effects of existing hydropower operations in cold climates.
Thermal and ice modeling for the reservoir and the general thermal modeling for the river during
the 5 months when ice is not present will be accomplished under the Water Quality Modeling
Study (Study 5.6). The output from that work will be used in this river ice processes study.
Likewise, open water flow routing will be performed under the Fish and Aquatics Instream Flow
Study (Study 8.5), while ice-affected flow routing will be performed by this study.
3. STUDY AREA
3.1. Observations
The ice processes observation study area includes the 234-mile segment of river between tidewater
and the Oshetna River confluence (below PRM 235.2 [RM 233.4]). Observations of open leads,
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break-up progression, and freeze-up progression will be made in this area. In addition, ice
thickness, top-of-ice elevations, and under-ice water stages will be surveyed in the Middle River
to calibrate and verify a predictive ice model.
3.2. Middle River River1D Ice Processes Modeling
Predictive ice, hydrodynamic, and thermal modeling using River1D is planned for the Middle
River between the Three Rivers Confluence near Talkeetna (PRM 103.8 [RM 100]) and the
proposed dam (PRM 186.8 [RM 184]).
3.3. Middle River River2D Focus Area Ice Modeling
Several Focus Areas determined in conjunction with the Instream Flow Studies (Studies 8.5-8.6)
in the Middle River will receive more detailed ice modeling and observation attention. Depending
on the local channel geometry, either detailed River1D or River2D models will be developed, and
observations of ice-cover progression, ice thickness, and open leads will be more detailed in order
to calibrate these models. See the Instream Flow Study (RSP Section 8.5) for criteria and potential
sites.
3.4. Lower River
There are currently no accepted models for predicting dynamic ice processes on complex braided
channels such as those found in the Lower Susitna River downstream of Talkeetna; therefore, no
hydrodynamic modeling is planned for the 100-mile reach between tidewater and the Talkeetna
River (up to PRM 103.8 [RM 100]). However, there is a need to assess the potential for change to
ice cover on the Lower River both for fish habitat studies and to understand the potential effects
of the Project on winter transportation access and recreation, which depend on ice cover on the
Lower Susitna River. Project effects to the Lower River will be based on the magnitude of change
seen at the downstream boundary of the River1D model (approximately PRM 103.8 [RM 100]),
the estimated contributions of frazil ice to the Lower River from the Middle River determined by
observations and modeling, and with simpler steady flow models (HEC-RAS with ice cover) for
short sections of interest in the Lower River (RSP Section 7.6.4.10).
4. METHODS AND VARIANCES
The observation and modeling efforts described below were used to characterize the Susitna River
ice regime, identify spatial and temporal variations in ice processes, and provide information on
the physical channel environment in the winter to other study disciplines. Characterizing the
existing ice regime and its variability provided a basis for evaluating the impacts of the project.
4.1. Aerial Reconnaissance
Aerial reconnaissance of ice processes were performed from tidewater to the Oshetna River
confluence (up to PRM 235.2 [RM 233.4]). The methods/variances are reported in Study Plan 7.6,
ISR Part A, Section 4.1. No additional aerial reconnaissance work has been performed on this task
since it was reported out in Study 7.6 Technical Memorandum: Detailed Ice observations October
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2013- May 2014 filed in September 2014. Following the October 17, 2014 ISR meeting for the
Ice Processes in the Susitna River Study, AEA requested that an alternate format be developed to
graphically present the freeze-up progression and open lead survey data. These alternate
visualizations are presented in Appendix A of this SIR. This task has been completed.
4.2. Time-Lapse Camera Monitoring
Time-lapse cameras were used to monitor break-up and freeze-up at locations corresponding to
flow routing model instrumentation, key ice processes, and fish habitat locations. The
methods/variances are reported in Study Plan 7.6, ISR Part A, Section 4.2. No work has been
performed on this task since it was reported out in Study 7.6 Technical Memorandum: Detailed
Ice observations October 2013 - May 2014 filed in September 2014. This task has been completed.
4.3. Ice Measurement Data
Field data were collected at several telemetered data network stations in accordance to the
methods/variances reported in Study Plan 7.6, ISR Part A, Section 4.3. No work has been
performed on this task since it was reported out in Study 7.6 Technical Memorandum: Detailed
Ice observations October 2013 - May 2014 filed in September 2014. A modification of this task
since the filing of the Study Plan 7.6, ISR in June 2014 is the continuation of this task to provide
ice and snow thickness and water elevation measurements at specific locations within FA-128 for
further calibration of the ice modeling efforts.
4.4. Other Field Data
The Riparian Instream Flow Study, Study Plan 8.6, ISR Part A, Section 4.4 describes the
methods/variances reported in the collection of ice scar data on trees along the Middle River reach.
Work continues to finalize this task of Study 8.6 and coordinate with Study 7.6 and will be reported
in future TM’s.
4.5. Modeling of River Ice Processes
A one dimensional model of river ice processes (River1D) and two dimensional models of select
Focus Areas (River2D) continue to be developed and calibrated for the Middle River reach of the
Susitna River. The methods/variances are reported in the RSP Section 7.6.4.6 through 7.6.4.9 and
in Study Plan 7.6, ISR Part A, Section 4.5. Appendix B of this SIR presents the initial open water
calibration of the River1D model. Appendix C of this SIR presents the open water calibration of
the River2D model of FA-128 (Slough 8A). As a modification of this task, the River1D modeling
of the Middle River reach will continue. River2D modeling of specific Focus Areas will also
continue.
4.6. Lower River Assessment
The primary impact of Project operations on the Lower River in the winter is likely to be increased
stage owing to reservoir releases in excess of natural winter discharge. An assessment of winter
stages on the Lower River was conducted in accordance with the methods/variances reported in
Study Plan 7.6, ISR Part A, Section 4.6. No work has been performed on this task since it was
reported out in Study 7.6 ISR Part A, Section 5.5.4 and Appendix A. This task has been completed.
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4.7. Review and Compilation of Existing Cold Regions Hydropower
Project Operations and Effects
A review of literature describing hydropower projects in northern countries was conducted to
develop a white paper describing possible effects of project operations. The methods/variances
are presented in Study Plan 7.6, ISR Part A Section 4.7. This white paper was reported out as
Study Plan 7.6, ISR Part C – Appendix C. This task has been completed.
5. RESULTS
Results reported out in this SIR include the alternate visualizations of the freeze-up progression
maps and open lead survey information. The formulation and open water calibration of the
River1D model of the Middle River and the River2D model of Focus Area 128 (Slough 8A) are
also presented.
5.1. Alternate Visualizations of Freeze-up Progression and Open
Lead Survey Information
Following the October 17, 2014 ISR meeting for the Ice Processes in the Susitna River Study,
AEA requested that an alternate format be developed to graphically present the freeze-up
progression and open lead survey data. Stakeholders requested that the information be placed in
more of a map-based format rather than a graphical indication by river mile. Data from the aerial
surveys and other ground-based observations were used to develop geographic information system
(GIS) representations of a simplified Susitna River Corridor on a single page. Data were plotted
on these base maps for the 2012 and 2013 freeze-up, as well as the open lead survey information
of March 2013, February 2014, and April 2014. The maps show where the river was ice-covered,
open, or open with flowing frazil ice on given observation dates. Up to three dates are provided
on each map to visualize the progression of the growing cover. Location of open leads, identified
as thermal leads or velocity leads were also plotted on base maps for the dates of the open lead
surveys. Also, to provide a comparison to the 1980’s study data, freeze-up progression maps were
developed for 1980-1985 and open lead survey information from 1982-83. In addition to the series
of freeze-up progression maps for each year, a figure has been produced which includes the
discharge hydrograph at the USGS Gold Creek gage and air temperature record at Talkeetna for
the period of October 1 through December 31 for each year. These figures include a symbol on
the discharge hydrograph to designate the dates of the observations and demonstrate the changes
that occur in the discharge over the freeze-up period. While the discharges and temperatures have
varied over the years, it has been observed that the freeze-up progression and locations of open
leads during the winter period are similar in manner and location. The locations of breakup jams
and accumulations of ice in the overbank areas also follow similar patterns. The combination of
the 1980’s data and the field observations and data collected during the spring 2012 through spring
2014 period has provided a very complete data set for a variety of freeze-up, winter, and breakup
conditions. The alternate visualizations demonstrate these similarities and ranges of natural
conditions and are presented in Appendix A of this SIR.
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5.2. River1D Middle River Model Development and Initial Open Water
Calibration
The Middle River Reach River1D Ice Processes Model was developed for initial open-water
calibration and for comparison with results from the Open-water Flow Routing Model (RSP
Section 8.5). The River1D model domain included the Susitna River mainstem from the proposed
dam site (PRM 187.2 [RM 184.4]) to a downstream boundary (PRM 80.0 [RM 76.1]) located
approximately 20 miles downstream of the Talkeetna River confluence. Discharge and stage data
for four calibration events were compiled during time periods in 2012 and 2013. These events
covered a range of discharge at Gold Creek (PRM 140) from 6700 to almost 73,000 cfs, discharges
that represent everything from late fall just prior to freeze-up through discharges that would result
in side channel slough and lower terrace flooding. A validation event was also run for a time
period during the summer of 2013. The initial open water calibration events showed the model
mean relative discharge errors for the USGS gage at Gold Creek to be 0.5 to 0.9 %. The mean
absolute error in water surface elevation at the various calibration points (ESS Stations) ranged
from 0.1 to 1.0 feet for the calibration events. Some of the error in water surface elevation was
attributed to the measuring stations (ESS and USGS gage stations) being different than the reported
output for specific River1D cross sections. The River1D model development, background, and
initial open water calibration are presented in Appendix B of the SIR.
5.3. River2D Model Development and Open Water Calibration for
Focus Area 128 (Slough 8A)
River2D is a two-dimensional model used to determine water velocities, depths, and the effects of
a laterally stationary but vertically varying ice cover. The model can be run in either steady or
unsteady flow conditions. A River2D model was developed for Focus Area 128 (Slough 8A), an
important spawning and rearing area in the Susitna River. The model was calibrated to open water
conditions based on field data of water velocities, discharge, and water elevation collected during
June and July 2013. The FA-128 (Slough 8A) River2D model was shown to perform very well
with three goodness of fit parameters describing the model performance. The RMSE (Root-Mean-
Square Error) ranged from 0.2 - 0.5 feet for all calibration runs. The theory and basis of the
River2D modeling, development of the FA-128 model and calibration to open water conditions
are presented in Appendix C of the SIR.
6. DISCUSSION
The overall goal of the Ice Processes in the Susitna River Study (Study 7.6) is to understand
existing ice processes in the Susitna River and to develop tools in order to predict post-Project ice
processes. Data collection and observations of the ice processes during freeze-up, mid-winter, and
breakup from spring 2012 through May 2014 have provided insights into the mechanisms of frazil
and anchor ice production, ice transport, shore ice growth, water elevation changes as the ice cover
progresses through an area, discharge variations and their effects during winter, and the breakup
process. Observations of the ice processes include aerial surveys, ground-based time-lapse camera
images, georeferenced photo and video images, measurements of ice thickness, and discharge. In
addition to the wealth of data that can be found at http://gis.suhydro.org/SIR/07-Hydrology/7.6-
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Ice/ several of the other studies also collected data that supported the ice studies. This included
the Fluvial Geomorphology Modeling below Watana Dam Study (Study 6.6), Groundwater Study
(7.5), Instream Flow Studies (Studies 8.5-8.6), Fish and Aquatics Study (Studies 9.12), and the
Riparian Vegetation Study Downstream of the Proposed Susitna-Watana Dam (Study 11.6). The
remote camera images and data recorded by the Susitna-Watana Hydroelectric Data Network
system (Instream Flow Studies) were particularly useful in determining ice conditions between
aerial surveys and for water level changes due to the presence or movement of the ice cover.
Another source of data on ice processes is the wealth of information compiled during the 1980’s
studies of the project area. Freeze-up cover progression for those years is presented alongside the
2012 and 2013 freeze-up progression in Appendix A of this report. The two sets of data are
complimentary with similar bridging locations, timing of the cover formation, and the occurrence
and location of open leads (both thermal and velocity). While there are variations from year to
year due to changes in discharge, air temperatures, and the severity and duration of cold spells, the
processes are fairly uniform. This compilation of data on ice processes has allowed an assessment
of the baseline conditions in the Susitna River and how year to year variations impact water levels,
extent and duration of the ice cover and the wide range of conditions during the breakup period.
This understanding of the effects of variations will guide the River1D ice modeling efforts in both
reproducing the existing conditions (present and historic) as well as predicting the effects of post-
Project operations. The following general statements can be made concerning the existing ice
processes on the Susitna River:
Floating frazil ice first appears in the Middle and Lower Susitna River about the time that
the average daily air temperature reaches freezing at Talkeetna.
The discharge at the USGS Gold Creek gage drops to 5,000 cfs or below by late October
or early November each year. A short time later, the ice cover bridges at the mouth of the
Susitna River and begins to progress upstream.
The ice cover progresses steadily upstream and reaches Talkeetna in early to late
November, though it has reached Talkeetna as early as late October in very cold years and
as late as January in warmer years.
The discharge continues to fall throughout the freeze-up period, reaching 1,500-2,500 cfs
by the end of December.
As the ice cover progresses through an area, the stage (water elevation) increases by 3-8
feet due to the resistance to flow by the newly formed cover.
The ice cover continues to progress upstream, reaching Gold Creek (PRM 140) by early to
mid-December.
Additional cover bridging points exist within Devils Canyon (PRM 153-164) and near the
Dam site (PRM187.2).
During mid to late winter, the discharge is at its lowest and the ice cover elevation and
water level are noticeably decreased.
Both velocity and thermal open leads persist at many locations throughout the winter.
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Breakup can occur as early as late April and as late as the end of May and varies widely
from year to year in terms of severity. Even in mild breakup years, there can be limited
areas that experience jamming and overbank flooding. Severe years can experience
massive jams, extensive flooding and damage to riparian vegetation as well as the ARRC
tracks between Talkeetna and Gold Creek.
The River1D modeling to date has shown that the model is capable of reproducing the stage and
discharge for a wide range of unsteady events during open water conditions. As presented in
Appendix B of this report, the open water calibration and validation shows that the model provides
results well within the 1 foot tolerance for an unsteady one dimensional model. The preliminary
water temperature modeling has shown that the River1D model is very capable at predicting water
temperature cool down. The River2D model has been used to predict water elevations and
velocities in two dimensions. The development of a model for Focus Area 128 (Slough 8A) and
its open water calibration is presented in Appendix C. Both of these models will be used to assess
the impacts of changes in winter discharge rates on the ice processes in the Middle River and to
provide important winter conditions data to many other studies.
7. CONCLUSION
As presented in the various filings, the Ice Processes in the Susitna River Study has completed
many of the tasks established in Section 7.6 of the Revised Study Plan (RSP). Specifically:
Documentation of the timing, progression, and physical processes of freeze-up and break-
up during 2012–2014 between tidewater and the Oshetna River confluence (PRM 235.2
[RM 233.4]), using historical data, aerial reconnaissance, stationary time-lapse cameras,
and physical evidence has been completed and reported out in Study Plan 7.6, ISR filed in
June 2014, the Study 7.6 Technical Memorandum: Detailed Ice observations October 2013
- May 2014 filed in September 2014, and this SIR.
A white paper that investigated large river ice processes relevant to the Susitna River,
analytical methods that have been used to assess impacts of projects on ice-covered rivers,
and the known effects of existing hydropower operations in cold climates was completed
and reported out in the ISR.
An assessment of the Lower River was conducted using HEC-RAS to evaluate the effects
of changes in winter discharge on the water surface elevation as reported out in the ISR.
Observational data of existing ice processes were provided to several studies (Study 6.6,
7.5, 8.5-8.6, 9.12, 11.6, 12.5-12.7, and 15.7).
A River1D model of the Middle River reach was developed and calibrated for open water
conditions as reported out in this SIR.
A River2D model of Focus Area 128 (Slough 8A) was developed and calibrated for open
water conditions as reported out in the SIR.
Tasks that remain to be completed in order to meet the study objectives include:
2014-2015 STUDY IMPLEMENTATION REPORT ICE PROCESSES IN THE SUSITNA RIVER (STUDY 7.6)
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Calibration of the River1D model of the Middle River reach for ice-covered conditions.
The calibrated model will be used to develop pre-project and with-project conditions (ILF-
1) of ice cover extent, water levels and velocities throughout the Middle River reach
specifically for 1976 (cold year), 1981 (warm year), and 1985 (average year). Additional
historic and/or operational scenarios will be modeled as needed.
Using the results of the River1D modeling, develop ice-covered models of Focus Area 128
(Slough 8A) and other focus areas as required. Field measurements of ice thickness, snow
depth, and water surface elevation will be collected at Focus Area 128 to facilitate model
calibration.
Conduct a model accuracy and error analysis arising from 1) simplifying assumptions in
the governing equations, 2) interpolation between measured points, and 3) error in
measuring input data.
Provide modeling results to be used as input to various other Studies modeling efforts as
required.
8. LITERATURE CITED
AEA (Alaska Energy Authority). 2012. Revised Study Plan (RSP): Susitna-Watana Hydroelectric
Project FERC Project No. 14241. Prepared for the Federal Energy Regulatory Commission
by the Alaska Energy Authority, Anchorage. December 2012.