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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
SuWa 251
Groundwater study (Study 7.5), groundwater and surface-water
relationships in support of riparian vegetation modeling, technical
memorandum
Author(s) – Personal:
Author(s) – Corporate:
Geo-Watersheds Scientific and R2 Resource Consultants, Inc.
AEA-identified category, if specified:
September 30, 2014 technical memorandum filings
AEA-identified series, if specified:
Series (ARLIS-assigned report number): Existing numbers on document:
Susitna-Watana Hydroelectric Project document number 251
Published by: Date published:
[Anchorage, Alaska] : Alaska Energy Authority, [2014] September 2014
Published for: Date or date range of report: Alaska Energy Authority
Volume and/or Part numbers:
Final or Draft status, as indicated:
Attachment D
Document type: Pagination:
Technical memorandum vi, 42, 9 p.
Related work(s): Pages added/changed by ARLIS:
Cover letter to this report: Susitna-Watana Hydroelectric Project,
FERC Project no. 14241-000; Third set of 2014 technical
memoranda for Initial Study Plan meeting. (SuWa 247)
Attachments A-C (SuWa 248-250) and E-F (SuWa 252-253)
Added cover letter (3 pages)
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 30, 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
Third Set of 2014 Technical Memoranda for Initial Study Plan Meetings
Dear Secretary Bose:
As the Alaska Energy Authority (AEA) explained in its September 17, 2014 filing
with the Federal Energy Regulatory Commission (Commission or FERC) for the
proposed Susitna-Watana Hydroelectric Project, FERC Project No. 14241 (Project), the
June 3, 2014 Initial Study Report (ISR) provided for AEA to prepare certain technical
memoranda and other information based on 2014 work. In accordance with Commission
Staff direction, on September 17 and September 26, AEA filed and distributed the first
and second sets of technical memoranda and other information generated during the 2014
study season.
With this letter, AEA is filing and distributing the third set of technical
memoranda generated during the 2014 study season, as described below.
This third set of technical memoranda includes:
• Attachment A: Baseline Water Quality Study (Study 5.5) and Water Quality
Modeling Study (Study 5.6), Water Quality and Lower River Modeling
Technical Memorandum. This technical memorandum evaluates water quality
data collected during 2013 and 2014 for adequacy in representation of current
riverine conditions. This Technical Memorandum further includes an
assessment of whether to extend the Water Quality Modeling Study’s riverine
model below PRM 29.9.
• Attachment B: Mercury Assessment and Potential for Bioaccumulation Study
(Study 5.7), Evaluation of Continued Mercury Monitoring Beyond 2014
Technical Memorandum. This technical memorandum evaluates the need for
continued monitoring of mercury data beyond 2014 and whether the existing
data collection efforts are sufficient to satisfy objectives for characterizing
baseline mercury conditions in the Susitna River and tributaries (Revised
Study Plan (RSP) Section 5.7.1).
2
• Attachment C: Groundwater Study (Study 7.5), Preliminary Groundwater and
Surface-Water Relationships in Lateral Aquatic Habitats within Focus Areas
FA-128 (Slough 8A) and FA-138 (Gold Creek) in the Middle Susitna River
Technical Memorandum. This technical memorandum provides an overview
of the types of data and information that are being collected to support the
Task 6 activities of the Groundwater Study, and describes the methods and
techniques that are being applied in analyzing the data leading to development
of response functions to be used for evaluating Project operational
effects. The TM centers on the analysis for FA-128 (Slough 8A) and to a
lesser extent FA-138 (Gold Creek) and represents an expansion of the
presentation materials provided during the Proof of Concept meetings held on
April 15-17, 2014.
• Attachment D: Groundwater Study (Study 7.5), Groundwater and Surface-
Water Relationships in Support of Riparian Vegetation Modeling Technical
Memorandum. This technical memorandum provides an overview of the
types of data and information that are being collected to support the Task 5
activities within the Groundwater Study, and describes the methods and
techniques that are being applied in analyzing the data leading to development
of response functions for evaluating Project operational effects. The TM
provides analysis objectives for FA-115 (Slough 6A) as a primary example of
upland versus riverine dominated groundwater conditions. Additional
examples are shown for FA-128 (Slough 8A) and FA-138 (Gold Creek).
• Attachment E: Salmon Escapement Study (Study 9.7), 2014 Implementation
and Preliminary Results Technical Memorandum. This technical
memorandum describes 2014 implementation (including methods and
variances) of and preliminary results from the Salmon Escapement Study.
• Attachment F: Cook Inlet Beluga Whale Study Plan (Study 9.17), 2015
Implementation Plan Technical Memorandum. This implementation plan
describes the methods for study activities proposed for 2015 that would
implement the Cook Inlet Beluga Whale Study (instead of those described in
RSP Section 9.17.1).
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.
3
Sincerely,
Wayne Dyok
Project Manager
Alaska Energy Authority
Attachments
cc: Distribution List (w/o Attachments)
Attachment D
Groundwater Study (Study 7.5), Groundwater and Surface-Water Relationships in Support of
Riparian Vegetation Modeling Technical Memorandum
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Groundwater Study
(Study 7.5)
Groundwater and Surface-Water Relationships in
Support of Riparian Vegetation Modeling
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
Geo-Watersheds Scientific and R2 Resource Consultants, Inc.
September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
TABLE OF CONTENTS
1. Introduction ........................................................................................................................1
1.1. Project Description.............................................................................................1
1.2. Study Background ..............................................................................................2
1.3. Technical Memorandum Objectives ..................................................................2
2. Study Area ..........................................................................................................................3
3. Methods ...............................................................................................................................3
3.1. Hydrology Observations ....................................................................................4
3.1.1. Water Surface Elevations Measurements ....................................... 4
3.1.2. Land-based and Aerial Photographic Imagery ............................... 5
3.2. Analysis Methods...............................................................................................5
3.2.1. Empirical Analysis Methods ........................................................... 5
3.2.2. Lateral Hydraulic Gradient Relationships ...................................... 6
3.2.3. Groundwater Modeling ................................................................... 6
3.3. Deviations from Study Plan ...............................................................................7
4. Hydrology and Lateral Hydraulic Gradient Results ......................................................7
4.1. FA-115 (Slough 6A) ..........................................................................................7
4.2. FA-138 (Gold Creek) .........................................................................................8
4.3. FA-128 (Slough 8A) ..........................................................................................8
5. Discussion............................................................................................................................9
5.1.1. Hydrology and Lateral Gradients.................................................... 9
5.1.2. Scaling Lateral Hydraulic Gradients to Riparian Process Domains
....................................................................................................... 10
6. Plans for 2015 ...................................................................................................................10
7. References .........................................................................................................................11
8. Figures ...............................................................................................................................13
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
LIST OF FIGURES
Figure 1. Susitna Watershed basin boundaries, showing the Project designation of upper, middle
and lower river segments. ..................................................................................................... 14
Figure 2. Susitna Watershed Middle River Segment, with geomorphic reaches and Focus Areas
indicated. ............................................................................................................................... 15
Figure 3. Data collection station short name convention used for continuously monitored
stations. ................................................................................................................................. 16
Figure 4. General location of FA-144 (Slough 21) Focus Area, showing major data collection
stations and aquatic and riparian transects. ........................................................................... 17
Figure 5. General location of FA-141 (Indian River) Focus Area, showing major data collection
stations and aquatic and riparian transects. ........................................................................... 18
Figure 6. Inset A shows locations of aquatic transect stations with continuously measured
parameters at FA-141 (Indian River) Focus Area. ................................................................ 19
Figure 7. Inset B shows locations of aquatic transect stations with continuously measured
parameters at FA-141 (Indian River) Focus Area. ................................................................ 20
Figure 8. General location of FA-138 (Gold Creek) Focus Area, showing major data collection
stations and aquatic and riparian transects. ........................................................................... 21
Figure 9. Inset A shows locations of aquatic transect stations with continuously measured
parameters at FA-138 (Gold Creek) Focus Area. ................................................................. 22
Figure 10. Inset B shows locations of aquatic transect stations with continuously measured
parameters at FA-138 (Gold Creek) Focus Area. ................................................................. 23
Figure 11. General location of FA-128 (Slough 8A) Focus Area, showing major data collection
stations and aquatic and riparian transects. ........................................................................... 24
Figure 12. Inset A shows locations of aquatic transect stations with continuously measured
parameters at FA-128 (Slough 8A) Focus Area. .................................................................. 25
Figure 13. Inset B shows locations of aquatic transect stations with continuously measured
parameters at FA-128 (Slough 8A) Focus Area. .................................................................. 26
Figure 14. Inset C shows locations of aquatic transect stations with continuously measured
parameters at FA-128 (Slough 8A) Focus Area. .................................................................. 27
Figure 15. General location of FA-115 (Slough 6A) Focus Area, showing major data collection
stations and aquatic and riparian transects. ........................................................................... 28
Figure 16. General location of FA-113 (Oxbow 1) Focus Area, showing major data collection
stations and aquatic and riparian transects. ........................................................................... 29
Figure 17. General location of PRM 112 (Project River Mile), showing the data collection
stations and riparian transects. .............................................................................................. 30
Figure 18. General location of FA-104 (Whiskers Slough) Focus Area, showing major data
collection stations and aquatic and riparian transects. .......................................................... 31
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 19. Inset A shows locations of aquatic transect stations with continuously measured
parameters at FA-104 (Whiskers Slough) Focus Area. ........................................................ 32
Figure 20. Inset B shows locations of aquatic transect stations with continuously measured
parameters at FA-104 (Whiskers Slough) Focus Area. ........................................................ 33
Figure 21. Annual hydrologic periods and period of record flow conditions for Susitna River at
Gold Creek. ........................................................................................................................... 34
Figure 22. Primary riparian cross section at FA-115 (Slough 6A) showing location of
groundwater wells, surface-water measurement locations, and the measured water levels on
April 24-25, 2014, with inferred water table. ....................................................................... 35
Figure 23. Groundwater elevations and surface-water levels for selected stations in FA-115
(Slough 6A) representing upland groundwater conditions and lower groundwater wells
affected by riverine processes. .............................................................................................. 35
Figure 24. Primary riparian cross section at FA-138 (Gold Creek) showing locations of surface-
water measurement locations, and typical upland features that indicate shallow groundwater
conditions. Water levels are shown for the cross-section survey date of 9/14/2014. ........... 36
Figure 25. Surface-water levels for stations in the FA-138 (Gold Creek) riparian transect. Major
hydrologic periods are indicated to show how the variation in water levels relate to the
climate and hydrologic processes relevant to these periods. ................................................ 36
Figure 26. Cross-section profile of the Upper Riparian Transect in FA-128 (Slough 8A) showing
the land surface profile, location of groundwater wells and surface water measuring points
on Upper Side Channel 8A and Slough 8A. Water levels are shown for the April 20-23,
2014. Water levels in Upper Side Channel 8A are ice effected. ........................................... 37
Figure 27. Water level data for Upper Side Channel 8A, Slough 8A, and groundwater wells
between the two surface-water features on the Upper Riparian Transect in FA-128 (Slough
8A). ....................................................................................................................................... 37
Figure 28. Hydrologic terrain examples for mountainous terrain and local-scale hyporheic scale
processes (Winter, 1998). ..................................................................................................... 38
Figure 29. Hydrologic terrain examples for riverine terrain and local-scale floodplain processes
(Winter, 1998). ...................................................................................................................... 38
Figure 30. Conceptual groundwater and surface water processes on a valley transect at FA-138
(Gold Creek) at a valley scale. .............................................................................................. 39
Figure 31. Conceptual groundwater and surface water processes on a valley transect at FA-138
(Gold Creek) at a broad floodplain scale showing adjacent older terraces. .......................... 39
Figure 32. Conceptual groundwater and surface water processes on a valley transect at FA-138
(Gold Creek) at a narrow floodplain scale showing relationships of river levels, shallow
water tables in the floodplain and seepage faces at slope breaks where springs are
commonly seen. .................................................................................................................... 40
Figure 33. Aerial images of the terrain hydrology and riparian cover at FA-138 (Gold Creek)
located on the right bank (looking downstream). Images were taken August 22, 2013. (a)
Shows the general location of the FA-138 Riparian transect, which goes from the edge of
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
the Susitna River across the upland terrace and crosses abandoned sloughs and beaver ponds
that are against the hill slope. (b) View of the abandoned beaver pond, developed in an old
slough. (c) View of an abandoned slough, adjacent and above the Susitna River................ 40
Figure 34. Secondary riparian cross section at FA-115 (Slough 6A) showing location of surface-
water measurement locations and the measured water levels on April 24-25, 2014 with
inferred water table. This transect is an example test transect for applying lateral hydraulic
gradients within a Focus Area. .............................................................................................. 41
Figure 35. Primary Riparian Cross Section at PRM-112 (Project River Mile). This transect is an
example test transect for applying lateral hydraulic gradients outside a Focus Area. .......... 41
Figure 36. Secondary Riparian Cross Section at PRM-112 (Project River Mile). This transect is
an example test transect for applying lateral hydraulic gradients outside a Focus Area. ..... 41
Figure 37. Primary riparian cross section at FA-115 (Slough 6A) showing location of
groundwater wells, surface-water measurement locations, and the measured water levels on
April 24-25, 2014 with inferred water table and the associated lateral hydraulic gradient
diagram showing the hydrologic features for defining hydrology characteristics in terms of
lateral hydraulic gradients. .................................................................................................... 42
APPENDICES
Appendix A. Hydrologic Stations Primary Station Purpose, Location and Data Collection
Parameters
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
LIST OF ACRONYMS AND SCIENTIFIC LABELS
Abbreviation Definition
AEA Alaska Energy Authority
°C Degrees centigrade
Cfs Cubic feet per second
Cm Centimeter
DEMs Digital Terrain Models
FA Focus Area
FERC Federal Energy Regulatory Commission
Fps Feet per second
GW Groundwater Study
GW/SW Groundwater/Surface Water
GWS Geo-Watersheds Scientific
IFS Instream Flow Study
ISR Initial Study Report
mg/L Milligrams per liter
MW Megawatts
NAVD88 North American Vertical Datum of 1988
NTU Nephelometric Turbidity Units
POC Proof of Concept
PRM Project River Mile
PT Pressure Transducer
RB Right Bank
RSP Revised Study Plan
RPD Riparian Process Domain
TM Technical Memorandum
USGS United States Geological Survey
WSE Water Surface Elevation
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vi September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
1. INTRODUCTION
1.1. Project Description
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 (Project) using the Integrated Licensing Process. The Project is located on the Susitna
River, an approximately 320-mile long river in the Southcentral Region of Alaska. The Project’s
dam site will be located at Project River Mile (PRM) 187.1. As currently envisioned, the Project
would include a large dam with an approximately 24,000-acre, 42-mile long reservoir. The
Project construction and operation would have an effect on the flows downstream of the dam
site, the degree of which will ultimately depend on final Project design and operations.
The Project reservoir is expected to fill during the summer months (May – August), when runoff
from snow melt and rainfall is greatest, to maximize power generation capability during the
winter months (October – April) when energy demand is high. As a result, seasonal changes to
Susitna River streamflow conditions during Project operations may include lower discharges
during the summer reservoir refill period and higher discharges during the winter relative to
current hydrologic conditions. In addition to these seasonal changes, the Project may be
operated in a load-following mode to meet energy demands on an hourly basis. During load-
following operations, the amount of water released from the reservoir would cycle daily
according to energy demands such that higher volumes would be released during peak-load
hours relative to off-peak hours. Seasonal and daily/hourly changes to Susitna River hydrology
would influence downstream aquatic and riparian resources and processes related to groundwater
conditions and groundwater surface water conditions. As a result, AEA developed and the
FERC approved (FERC 2013) a detailed Groundwater Study (GW) Study Plan (contained as
Section 7.5 in the December 14, 2012 Revised Study Plan [RSP]; see AEA 2012) containing
nine specific tasks that were collectively designed to evaluate the potential effects of Project
operations on groundwater resources.
Task 5 of the GW plan (Study 7.5) centers on defining groundwater/surface water (GW/SW)
relationships associated with riparian habitats within selected Focus Areas 1. This task is linked
with the Riparian Instream Flow Study (R-IFS) (RSP 8.6)) with one of the objectives being the
development of GW/SW response functions for different locations within a FA that can be used
to assess upland-dominated groundwater from riverine dominated GW/SW interactions resulting
from different Project operational scenarios. GW/SW analysis completed within the selected
FAs will provide a better understanding of how GW/SW processes operate more broadly and
will be used to draw inferences regarding Project operational effects at other locations within the
1 Focus Areas are specific geographic areas within the Middle Segment of the Susitna River that were selected to be intensively
evaluated across multiple resource disciplines (RSP 8.5.4.2.1.2) There are ten Focus Areas located in the Middle Segment of the
river (see R2 Resource Consultants 2013a). The Task 5 GW investigations were concerned with seven of the FAs including FA-
104 (Whiskers Slough), FA-113 (Oxbow 1), FA-115 (Slough 6A), FA-128 (Slough 8A), FA-138 (Gold Creek), FA-141 (Indian
River), and FA-144 – (Slough 21), with studies concentrated in FA-104, FA-115 and FA-128.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Middle Segment of the river. Defining lateral hydraulic gradients is a key approach to achieving
this objective.
This Technical Memorandum (TM) provides an overview of the types of data and information
that are being collected to support the Task 5 GW/SW activities, and describes the methods and
techniques that are being applied in analyzing the data leading to development of response
functions for evaluating Project operational effects. The TM provides analysis objectives for
FA-115 (Slough 6A) as a primary example of upland versus riverine dominated groundwater
conditions. Additional examples are shown for FA-128 (Slough 8A) and to a lesser extent FA-
138 (Gold Creek). The empirical data and analysis also represents an expansion of the
presentation materials provided during the Riparian Proof of Concept (POC) meetings held on
April 29-30, 2014. During those meetings, information concerning the locations and methods for
data collection were presented, as well as preliminary analysis showing key GW/SW processes
taking place in different Focus Areas. Additional data and empirical data analysis are shown,
along with the definition of lateral hydraulic gradients and the proposed approach for scaling to
the riparian process domains of the Middle River. An important qualifier of this TM is that
although site specific data have been used, the data analysis techniques and the results presented
herein may be revised as additional data are collected.
1.2. Study Background
The Susitna River is a large glacial river that exhibits large hydrologic changes at hourly, daily,
and seasonal temporal scales. Susitna River discharge is typically the highest during the
snowmelt period in spring and early summer (June – August) and large, short-term fluctuations
in flow volumes often occur during summer in response to air temperature changes and
precipitation events. Mean monthly Susitna River streamflow for June, July, and August during
water years 1950 – 2010 ranged between 21,430 – 26,290 cfs (USGS Gold Creek gage
#15292000) (Curran 2012). During the open-water period, Susitna River streamflow is fed
primarily by surface and glacial runoff and water turbidity levels are high (> 200 nephelometric
turbidity units [NTU]) due to suspended glacial silt. Susitna River discharge levels typically
decline during September through November and are lowest during December through April
when the channel is largely ice covered. Winter ice processes include early winter ice
development and ice jams, mid-winter ice jams, and significant ice jams during spring snowmelt
and breakup. Mean monthly Susitna River streamflow for December through April during water
years 1950 – 2010 ranged between 1,303 – 1,893 cfs (USGS Gold Creek gage #15292000)
(Curran 2012). Winter streamflow is fed primarily by groundwater and consequently discharge
is stable and slowly dropping and water turbidity is low (<10 NTU).
1.3. Technical Memorandum Objectives
This Technical Memorandum (TM) is specific to Groundwater Study (Study 7.5) and Riparian
IFS (Study 8.6) hydrologic analyses. It demonstrates, through presentation of preliminary field
results, GW/SW interaction elements. The objectives of this TM are (1) to provide status update
concerning general 2014 groundwater and surface-water data collection activities in support of
Riparian IFS, (2) provide GW/SW analyses and results using FA-115 (Slough 6A) as a primary
example, (3) present additional GW/SW field results from FA-138 (Gold Creek) and FA-128
(Slough 8A), (4) present select examples from PRM 112 (Slough 6A) to introduce example sites
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
where limited data is used to show lateral hydraulic gradient characterizations outside the Focus
Areas, and (5) provide an update on GW/SW modeling progress. Groundwater Study GW/SW
data collection and analyses for support of Aquatic IFS (Study 8.5) and Riparian IFS (Study 8.6)
are integrated and complementary. Plans for 2015 data collection are also presented.
2. STUDY AREA
As established by RSP Section 7.5.3, the overall study area related to groundwater processes
includes primarily the Middle River Segment of the Susitna River that extends from PRM 102.4
to PRM 187.1 as well as portions of the Lower River Segment associated with domestic wells
and riparian transect locations in the Lower River, and the lowest portion of the Upper River
Segment near the proposed dam site associated with potential groundwater changes relative to
reservoir construction and operations. Figure 1 shows these river segments and the general
watershed boundary of the Susitna River. Figure 2 shows the location of Instream Flow Study
(Study 8.5) Focus Areas and geomorphic reaches for the Middle River Segment. The
Groundwater Study established data collection stations in various Focus Areas. The naming
convention for the stations is shown in Figure 3 and descriptions of current data collection
parameters are shown in the tables in Appendix A. The Focus Areas and Groundwater Study
hydrologic stations established in 2013 and 2014 are shown in Figure 4 through Figure 20.
3. METHODS
The described study methods are directly linked to the Riparian Instream Flow Study (Study 8.6)
and associated with a number of other multidisciplinary resource studies that are jointly working
on the Focus Areas including the Fish and Aquatics Instream Flow Study (Study 8.5),
Geomorphology studies (Studies 6.5 and 6.6), Ice Processes Study (Study 7.6), and Water
Quality studies (Studies 5.5 and 5.6). The overall goal of this study component is to collect
information and data to define riparian vegetation and GW/SW interactions and function at a
number of Focus Area locations. Focus Area results will be used to extrapolate effects to the
riparian domain scale. These process relationship analyses will allow for assessment of potential
Project operation effects on GW/SW interactions and associated riparian vegetation.
The methods employed as part of the analysis are described below and include field efforts to
collect water surface elevation, as well as collection of stationary and aerial imagery to allow
visual assessments of ice processes affecting surface water conditions and riparian vegetation.
The photos also help verify precipitation conditions, leaf-out, leaf-off and other environmental
information at the remote field areas. Methods are also presented that describe the types of data
analysis that were used to evaluate lateral hydraulic gradients and define various GW/SW
relationships both in terms of stage.
Ultimately, various hydraulic and physical models, including surface water hydraulic (1-D and 2-
D), geomorphic reach analyses, and ice processes will be integrated as needed to allow
assessment of riparian processes and hydrologic controls (see Study 8.6) under both existing
conditions and Project operational scenarios. The results of the GW study will be used to draw
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
appropriate inferences on GW/SW processes at the river segment and riparian process domain
scale.
As described in the Initial Study Report (ISR), empirical data are being collected at five Focus
Areas (FA-104 (Whiskers Slough), FA-113 (Oxbow 1); FA-115 (Slough 6A), FA-128 (Slough
8A); and FA-138 (Gold Creek)) to define GW/SW interactions (see ISR 7.5, Figures 4.5-2, 4.5-
3, 4.5-5, and 4.5-6). Additional stations were established for manual measurements in 2014 in
PRM 112 (Slough 6), FA-141 (Indian River) and FA-144 (Slough 21). The data collection
stations established within each Focus Area serve multiple study needs with some of the stations
collecting measurements of groundwater level and water quality (temperature and conductivity),
some stations collecting measurements of surface water levels, discharge, and water quality, as
wells as some fixed stations collecting time lapse photographs to document hydrologic and
riparian vegetation condition changes over time.
3.1. Hydrology Observations
3.1.1. Water Surface Elevations Measurements
Water surface elevations being measured at both groundwater stations and surface-water stations
within each of the Focus Areas are shown in Figure 4 through Figure 20. These measurements
are intended to provide data at the various stations including those associated with specific
transects for analysis of GW/SW interactions over the range of hydrologic conditions from
summer through fall freeze-up, winter, and spring snowmelt and breakup.
At stations with pressure transducers (PTs), manual water level measurements were made to help
process the continuous data and to apply data shifts and corrections as needed due to potential
movement of the PT. The PTs used for the study also record water temperature at the location of
the sensor. In addition, intergravel water temperature profiles were measured via placement of
thermistor strings that recorded temperatures at different depths within the substrate. Depending
on the complexity of the hydrologic station, PTs are either part of the overall sensor suites
measured by Campbell Scientific Inc. CR1000 or CR200X data loggers, or are self-logging
pressure transducers at groundwater and surface-water stations where fewer measurements are
required.
Manual water level measurement at surface-water stations are frequently made by level-loop
surveying. Level-loop surveys are performed with optical survey levels. Measurement goals for
level loop closures are 0.02 ft. There are three to four reference elevation benchmarks to use for
summer and winter surveying at a majority of the stations. These benchmarks have had at least
one measurement point surveyed by RTK survey methods to establish sea level datum at each
station.
All groundwater wells were installed by drive point methods with pre-drilling to help installation
when needed. The wells all have the top of galvanized casing protected by enclosures that have
survey measurement control marks on them. These measurement locations are surveyed by level
loop survey methods and used as a reference point to measure the depth to groundwater in the
well.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
In 2014, 42 staff gages were installed in various Focus Areas and other locations to provide field
crews from various studies the ability to take water level readings at these locations. This same
approach was successfully used in the 1980s Susitna studies. These locations are all in lateral
side channels, sloughs and beaver ponds where they require less maintenance during the summer
ice free hydrologic period.
Listings of all groundwater and surface-water stations used in the GW study are provided in
Appendix A, Table 1 through Table 8, which are organized by Focus Area or PRM. The station
information tables include both stations and sensors installed in 2013 and in new data collection
sites established in August 2014. One non-Focus Area location is included at PRM 112 (Slough
6).
3.1.2. Land-based and Aerial Photographic Imagery
Visual documentation of water levels and other hydrologic features is available at the Focus
Areas via a series of land-based stationary time-lapse cameras. Photographs from these cameras
can be used in part to help document the weather, hydrologic and vegetation changes within a
Focus Area over time, and the connectivity of hydrologic processes to riparian vegetation.
In addition, aerial surveys were completed during a number of the field efforts to photo
document conditions in all the surface-water sloughs and side channels, beaver ponds and other
hydrologic features in each Focus Area. These empirical photographic data sets help document
ice and snow cover conditions during winter conditions, changes in channel conditions, changing
beaver dam and channel changing activities, and the general characteristics of the surface-water
features in each Focus Area.
3.2. Analysis Methods
The below sections describe general data collection and preliminary data analysis methods used
in this TM. The analysis considered four main periods where hydrologic conditions and related
GW/SW interactions may vary. These periods are defined as Fall Freeze Up, Winter (ice cover),
Spring Break-Up, and Summer (ice free) and are depicted in Figure 21, which also shows the
period of record daily mean flow statistics for the Susitna River at Gold Creek USGS gaging
station (15292000) (USGS, 2014). Using these seasons to help describe GW/SW interactions is
important as the hydrologic processes and boundary conditions change over the seasons, as does
riparian vegetation, and so will Project operations.
3.2.1. Empirical Analysis Methods
As an initial step in the Focus Area analysis, water level and temperature data were plotted
together in various combinations to examine relationships between groundwater conditions and
adjacent surface water features. Time series plots were then used at different time scales to show
response changes between GW/SW systems. The primary information used to study these
interactions are water levels as relative pressure (water height) gradients are the foremost process
driving interactions. Temperature data were also used as indicators of GW/SW mass interaction,
since temperatures differ between groundwater and surface water. Manual discharge
measurements in channels were used to measure groundwater recharge to surface water bodies
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(upwelling or gaining stream reaches) or discharge from surface water to groundwater
(downwelling or losing stream reaches).
For the GW Study, the study design for understanding riparian processes consisted of transects
with multiple wells crossing different vegetation zones and surface-water feature of interest
(slough, side channel). Water elevations in the surface water features and all groundwater
locations across transects were used to develop a 2-D cross section view of GW/SW interactions.
The top of the unconfined groundwater surface is also called the “water table”. By comparing the
difference between groundwater and surface water levels across the transect, hydraulic gradients,
or water table slopes can be calculated from aquifer positions to determine the horizontal and
vertical flow direction, and the extent of GW upwelling or SW downwelling between surface
water and adjacent aquifers. In shallow water table settings, it is common to use a combination
of shallow wells and surface-water features to map out the top of the water table. Empirical data
comparisons between different types of lateral aquatic habitats and hydrologic conditions were
used to understand and characterize the range of GW/SW interactions taking place across Focus
Areas.
3.2.2. Lateral Hydraulic Gradient Relationships
A primary objective of this TM is to show analytical approaches and examples for defining
lateral hydraulic gradients. The gradients can be described as water table slope from upland (hill
slopes, high terraces) down to the main channel of the Susitna River. The water table slope is
defined by the top of ground water surface and intersecting surface-water features such as
streams, sloughs, side channels, wetlands, spring, and beaver ponds. By surveying all
measurement locations to a common vertical datum (NAVD88), these elevations can then be
compared with other sources of information, such as digital terrain models (DEMs), outputs of 2-
D flow routing models and aerial images.
The temporal data collection of water level information across the different hydrologic seasons is
then used to define the important boundary conditions, such as upland groundwater aquifers, and
surface water features across the transects to the main channel of the Susitna River.
3.2.3. Groundwater Modeling
In addition to the analysis of empirical data that are presented in this TM, 2-dimensional (2-D)
cross-sectional groundwater models are being developed for each of the riparian transects in FA-
128 (Slough 8A), FA-115 (Slough 6A) and FA-104 (Whiskers Slough). These models will
provide a better understanding of GW/SW interactions and how they vary across different types
of lateral aquatic and riparian habitats under natural flow conditions. In addition to the 2-D
modeling efforts, FA-128 (Slough 8A) was selected for development of a 3-dimensional (3-D)
model for use in the Study 7.5 Task 5 IFS-Riparian studies and for comparative purposes with
the 2-D models. The purpose of the 3-D model is to develop an understanding of how to apply
the process understanding in the 2-D GW/SW models to the Focus Area scale and make
appropriate inferences at the riparian process domain scale.
For this, the USGS modeling package MODFLOW (Feinstein et al. 2012; Maddock et al. 2012;
USGS 2005) was selected for use based on guidance in ASTM D6170 “Standard Guide for
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Selecting a Groundwater Modeling Code” (ASTM, 2010). ASTM standard D5981 is being used
to help develop calibration goals and procedures for groundwater modeling efforts (ASTM
2008).
To date, elevation surveying has been completed at each transect to provide the upper land
surface boundary and location of monitoring wells and other empirical observation points.
Methods for integrating input data from the 1-dimensional (1-D) HEC-RAS model (summer, ice-
free) (ISR 8.5; Appendix K (R2 2014)) are under development. The 2-D hydraulic models will
be used to develop synthetic stage-discharge relationships at the groundwater modeling transects
for specific flow conditions simulated by the 1-D hydraulic models. During fall freeze-up,
winter, and spring breakup, output from the Ice Processes Study (Study 7.6) River1D model will
be used for future stage input.
3.3. Variances from Study Plan
The GW study methods were implemented as described in the Study Plan with only some
variances in schedule for tasks not related to field activities (see ISR Study 7.5, Section 4.5).
4. HYDROLOGY AND LATERAL HYDRAULIC GRADIENT RESULTS
Hydrologic observations of GW/SW interactions and related data have been made in the study
areas since late summer 2013 and have covered the four primary seasons for the annual
hydrologic year (Figure 21). One station (ESSFA128-1) (Figure 13) was established as part of
the 2012/13 winter studies conducted by Instream Flow (Study 8.5), Fish Distribution and
Abundance in the Middle and Lower River (Study 9.6) and GW (Study 7.5) study teams and
measured end-of-winter 2013 conditions as well as spring snowmelt and breakup in 2013. The
2013/14 winter season and summer 2014 was intensely monitored by the network of
groundwater and surface water stations in the relevant Focus Areas. During the April late-winter
field trip in 2014, surface-water discharge was measured to characterize groundwater
recharge/discharge (upwelling/downwelling) in select lateral habitats in FA-138 (Gold Creek)
(Slough 11); FA-128 (Slough 8A) (Slough 8A); and FA-104 (Whiskers Slough) (Whiskers
Creek, Slough 3A, Whiskers Slough).
An early snowmelt and breakup period was measured in late April and early May 2014. This
was followed by a period of lower water level conditions in late May and early June followed by
typical summer precipitation stage events in June through August. Additional surface water
level, discharge and water-quality measurements were collected in September 2014 to help
characterize the end of the summer 2014 hydrologic period.
4.1. FA-115 (Slough 6A)
The hydrology data collected in FA-115 (Slough 6A) in 2013 and 2014 covered a broad range of
hydrologic conditions. Figure 15 shows the general location of FA-115 (Slough 6A) and the
location of the primary and secondary riparian transects. The cross-section for the primary
transect is shown in Figure 22. The location of wells and surface-water measurement stations are
shown along with relevant surface-water features such as sloughs, beaver ponds and a side
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channel of the Susitna River. Groundwater and surface-water levels continuously measured from
2013 through 2014 are shown in Figure 23. The well located furthest from the secondary channel
is at station ESGFA115-2. This well is located just below the slope break in an area where
groundwater springs are common. A small upland stream, draining the area wetland, is also
being measured. The 2013 data shows very little water level variation along this hydrologic
boundary. The lower beaver pond on Slough 6A is measured by ESGFA115-5, along with an
adjacent well located on the river side of the beaver pond. Water levels in the beaver pond vary
more due to summer precipitation, winter ice development, and spring snowmelt, than
hydrologic interaction with the Susitna River. In comparison, the well adjacent to the beaver
pond at ESGFA115-5 shows some variation due to river stage changes. The well located
adjacent to the Susitna River side channel at ESGFA115-7 is shown for comparison. This well
shows the rapid response of groundwater levels to surface water stage changes.
4.2. FA-138 (Gold Creek)
FA-138 (Gold Creek) has a minor riparian transect located on the right bank (RB) of the Susitna
River main channel. The riparian transect covers an upland wetland area and has two surface-
water measuring stations (ESGFA138-6, ESGFA138-7, Figure 8, Figure 9). At the ESGFA138-7
station, field crews survey surface-water stage levels during station visits. This transect is just
downstream from the Susitna River at Gold Creek USGS gage and a simple offset is calculated
to adjust the stage values measured at the USGS gage to the transect location. The cross-section
of the riparian transect and associated hydrology features are shown in Figure 24. The
groundwater surface (water table) is at land surface for most of the riparian transect. The annual
surface water levels for the abandoned slough at ESGFA138-6 and the abandoned upland slough
at ESGFA138-7 are shown in Figure 25. The adjusted stage levels for the Susitna River at the
ESGFA138-7 location are also shown to help demonstrate the elevation differences between the
upland water features and the stage in the river. The data collected over 2013 and 2014 do not
show a riverine dominance in the shallow wetland or other surface-water features. Groundwater
recharge from uplands and summer precipitation and spring snowmelt are the controlling
hydrologic conditions maintaining the water levels in the upland wetlands.
4.3. FA-128 (Slough 8A)
There are two riparian transects in FA-128 (Slough 8A) (Figure 11, Figure 13, and Figure 14).
The upper riparian transect was chosen to illustrate an example of a floodplain that is more
riverine dominated throughout the transect (Figure 26). The upper riparian transect extends from
Upper Side Channel 8A across the island to Slough 8A. During the period water levels are
shown on the transect (4/20-23/2014), the water table gradient is from the side channel to Slough
8A. Water levels for the Upper Side Channel 8A and Slough 8A are shown in Figure 27. The
groundwater system responds rapidly to stage changes in the mainstem, with some of the highest
water table conditions occurring during winter (ice affected) period and spring snowmelt and
breakup. The continuous water level data shows different periods where groundwater levels
reverse. The data indicates the water table conditions are highly dependent on the surface-water
boundary conditions in the side channel and slough.
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5. DISCUSSION
The data collection efforts in 2013 and 2014 characterize the upland dominated groundwater to
riverine dominated groundwater conditions. FA-115 (Slough 6A) is a good representation of the
difference between upland groundwater controlled conditions on the high slopes and terraces
down to riverine dominated groundwater conditions near the Susitna River (Figure 22 and Figure
23). The upper riparian transect in FA-128 (Slough 8A) offers a contrast and shows riverine
dominated conditions (Figure 26 and Figure 27). The data from these and other transects will be
used to define the range of shallow groundwater conditions and the limits of riverine processes.
5.1.1. Hydrology and Lateral Gradients
The hydrology studied in the Focus Areas was viewed at the landscape scale by applying a
hydrologic terrain approach as described by Winter, 1998. Examples of hydrologic terrains that
apply to the Focus Area settings are shown in Figure 28 and Figure 29. The mountainous terrain
example is analogous to the Middle River section of the Susitna River passing through the
Talkeetna Mountains. Regional groundwater base flow recharges the river and adjacent
floodplain and hill slopes. Where groundwater intersects the land surface, seeps, springs,
wetlands and vegetation dependent on shallow groundwater conditions are observed. The
riverine terrain is seen in Focus Areas settings such as FA-128 (Slough 8A).
A combination of these hydrologic terrain settings can be seen in the FA-138 (Gold Creek)
Focus Area. Figure 30 shows a valley transect that crosses the FA-138 (Gold Creek) riparian
transect. The hydrologic groundwater and surface water processes will be similar to that shown
in Figure 28 and Figure 29. Groundwater recharge occurs throughout the recharge area, with
large recharge areas occurring above the floodplain. This is further illustrated at the floodplain
scale in Figure 31 and Figure 32. Field observations of seepage faces, shallow groundwater
conditions, and seasonal variation though the different hydrologic periods (Figure 21) help
demonstrate how these processes interact at the Focus Area scale.
The riparian transect in FA-138 (Gold Creek) shows a good example of a floodplain wetland
setting adjacent to the river that is controlled by groundwater and local precipitation and
snowmelt (Figure 24, Figure 25). The data collected over 2013 and 2014 demonstrate that water
level conditions in the wetland and associated water bodies are not affected by Susitna River
stage fluctuations. Aerial images of this cross section are shown in Figure 33. The abandoned
beaver ponds and sloughs in these sections are maintained by the regional groundwater discharge
to the area. This has been further observed by open water conditions in winter months in the
water bodies associated with warm groundwater discharge decreasing surface water freezing
during winter months.
Approaches were developed in 2014 to develop and transfer the understanding gained at the
riparian transect scale to the river segment and riparian process domain scales. An additional
transect was established in FA-115 (Slough 6A) (Figure 34) to help show the application of the
approach of lateral gradients within the Focus Area. Two additional examples are also shown for
Slough 6 at PRM 112 in Figure 17, Figure 35, and Figure 36. Manual water level measurement
stations (staff gages) at the PRM 112 cross-sections were established in 2014 to help develop and
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demonstrate the methods for transferring the understanding of lateral hydraulic gradients outside
of the Focus Area transects.
An example of the hydrologic features of the lateral gradients is shown in Figure 37 for FA-115
(Slough 6A). The upper portion of the figure shows measured conditions and surface hydrology
features that can be seen on the ground and in aerial photographs and imagery. The lower portion
of the figure shows areas of groundwater control and surface-water (riverine) control. A “hinge-
point” is defined as the location where Susitna River riverine flow and stage changes do not
significantly impact adjacent groundwater conditions and lateral water bodies. In this Focus Area
example, Slough 6A, a large beaver dam is located. The hydrologic boundary conditions at the
end of the riparian transect, where regional groundwater seeps and springs occur, show very little
annual fluctuation in water levels. The Susitna River is the boundary condition at the opposite
end of the hydraulic gradient. It varies with the processes taking place over the hydrologic
season’s characteristics for the area.
5.1.2. Scaling Lateral Hydraulic Gradients to Riparian Process Domains
The process understanding gained in the Focus Areas, and other analyses and modeling, will be
used for scaling the lateral hydraulic gradients to the river segment and riparian process domain
scale. A spatial analysis (GIS) approach will be developed using the Focus Area 2013/2014
GW/SW results. The analysis will integrate GW/SW field measurements, spatial GIS products
and 1-D/2-D flow routing models to define the extent of riverine influences on the groundwater
system and associated impact on riparian vegetation. The spatial approach will then be used to
scale up the Focus Area hydraulic gradient analysis to the river segment and riparian domain
scales.
6. PLANS FOR 2015
The schedule for completing the FERC-approved Study Plan is dependent upon several factors,
including Project funding levels authorized by the Alaska State Legislature, availability of
required data inputs from one individual study to another, unexpected weather delays, the short
duration of the summer field season in Alaska, and other events outside the reasonable control of
AEA. The GW studies associated with Task 5 will continue in 2015 with a focus on: a)
collection of hydrologic data (surface and groundwater) within FA-104 (Whiskers Slough), FA-
113 (Oxbow 1), FA-115 (Slough 6A), FA-128 (Slough 8A), FA-138 (Gold Creek), FA-141
(Indian River), and FA-144 (Slough 21); b) continued meteorological and limited sap flow data
collection through September 2015 for a second full season; c) data collection at lower river
stations for a full summer season in 2015, with stations removed end of September 2015, c)
continued analysis of empirical data and development of GW/SW and lateral hydraulic gradient
relationships; d) completion of MODFLOW modeling to support data analysis; e) development
of lateral gradient scaling approach and analysis; and e) development of specific
groundwater related parameter inputs needed to support the R-IFS (Study 8.6) modeling and
analysis, and Instream Flow (Study 8.5) Focus Area models as well as other modeling efforts
(e.g., Water Quality Model (Study 5.6); Fluvial Geomorphology Model (Study 6.6); Ice
Processes (Study 7.6).
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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.
AEA (Alaska Energy Authority). 2014. Initial Study Report: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. June 2014. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/type/documents/
ASTM. 2008. D5981 - 96(2008) Standard Guide for Calibrating a Groundwater Flow Model
Application, ASTM, 19 pp.
ASTM. 2010. D6170 - 97(2010) Standard Guide for Selecting a Groundwater Modeling Code,
ASTM, 19 pp.
Curran, J.H., 2012, Streamflow record extension for selected streams in the Susitna River Basin,
Alaska: U.S. Geological Survey Scientific Investigations Report 2012–5210, 36 p.
Feinstein, D.T., Fienen, M.N., Kennedy, J.L., Buchwald, C.A., and Greenwood, M.M. 2012.
Development and application of a groundwater/surface-water flow model using
MODFLOW-NWT for the Upper Fox River Basin, southeastern Wisconsin: U.S.
Geological Survey Scientific Investigations Report 2012–5108, 124 p.
Montgomery, D. 1999. Process domains and the river continuum. Journal of the American
Water Resources Association 35 (2): 397-410.
FERC (Federal Energy Regulatory Commission). 2013. Study Plan Determination on 14
remaining studies for the Susitna-Watana Hydroelectric Project. Issuance 20130401-
3022. Susitna-Watana Hydroelectric Project FERC No. P-14241. April 1, 2013.
R2 Resource Consultants, Inc. 2014. Hydrology and Version 2 Open-water Flow Routing
Model. Initial Study Report, Study 8.5, Part C, Appendix K. Susitna-Watana
Hydroelectric Project, FERC No. P-14241. Prepared for Alaska Energy Authority,
Anchorage, Alaska. June 2014. 129 pp. http://www.susitna-watanahydro.org/wp-
content/uploads/2014/06/08.5_IFS_ISR_PartC_1_of_2.pdf.
R2 Resource Consultants, Inc., GW Scientific and ABR, Inc. 2013. Technical Memorandum:
Riparian IFS, Groundwater and Riparian Vegetation Studies FERC Determination
Response. Prepared for AEA June 2013. 12 pp.
USGS (U.S. Geological Survey). 2014. USGS Current Conditions for Susitna River at Gold
Creek, accessed August 30, 2014, at http://nwis.waterdata.usgs.gov/ak/nwis/uv
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Viereck, L.A., C.T. Dyrness, A.R. Batten, and K.J. Wenzlick. 1992. The Alaska Vegetation
Classification. Pacific Northwest Research Station, U.S. Forest Service, Portland, OR.
Gen. Tech. Rep. PNW-GTR-286. 278 pp.
Wilson, K. B., P.J. Hanson, P.J. Mulholland, D.D. Baldocchi and S.D. Wullschleger. 2001. A
comparison of methods for determining forest evapotranspiration and its components:
sap-flow, soil water budget, eddy covariance and catchment water balance. Agricultural
and Forest Meteorology 106(2): 153-168.
Winter, T.C. 2001. The concept of hydrologic landscapes. Journal of the American Water
Resources Association 37: 335-349.
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8. FIGURES
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Figure 1. Susitna Watershed basin boundaries, showing the Project designation of Upper, Middle and LowerRriver segments.
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Figure 2. Susitna Watershed Middle River Segment, with geomorphic reaches and Focus Areas indicated.
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Figure 3. Data collection station short name convention used for continuously monitored stations.
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Figure 4. General location of FA-144 (Slough 21) Focus Area, showing major data collection stations
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Figure 5. General location of FA-141 (Indian River) Focus Area, showing major data collection stations
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Figure 6. Inset A shows locations of aquatic transect stations with continuously measured parameters at FA-141 (Indian River) Focus Area.
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Figure 7. Inset B shows locations of aquatic transect stations with continuously measured parameters at FA-141 (Indian River) Focus Area.
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Figure 8. General location of FA-138 (Gold Creek) Focus Area, showing major data collection stations and aquatic and riparian transects.
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Figure 9. Inset A shows locations of aquatic transect stations with continuously measured parameters at FA-138 (Gold Creek) Focus Area.
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Figure 10. Inset B shows locations of aquatic transect stations with continuously measured parameters at FA-138 (Gold Creek) Focus Area.
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Figure 11. General location of FA-128 (Slough 8A) Focus Area, showing major data collection stations and aquatic and riparian transects.
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Figure 12. Inset A shows locations of aquatic transect stations with continuously measured parameters at FA-128 (Slough 8A) Focus Area.
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Figure 13. Inset B shows locations of aquatic transect stations with continuously measured parameters at FA-128 (Slough 8A) Focus Area.
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Figure 14. Inset C shows locations of aquatic transect stations with continuously measured parameters at FA-128 (Slough 8A) Focus Area.
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Figure 15. General location of FA-115 (Slough 6A) Focus Area, showing major data collection stations and aquatic and riparian transects.
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Figure 16. General location of FA-113 (Oxbow 1) Focus Area, showing major data collection stations.
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Figure 17. General location of PRM 112 (Project River Mile), showing the data collection stations and riparian transects.
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Figure 18. General location of FA-104 (Whiskers Slough) Focus Area, showing major data collection stations and aquatic and riparian transects.
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Figure 19. Inset A shows locations of aquatic transect stations with continuously measured parameters at FA-104 (Whiskers Slough) Focus Area.
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Figure 20. Inset B shows locations of aquatic transect stations with continuously measured parameters at FA-104 (Whiskers Slough) Focus Area.
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Figure 21. Annual hydrologic periods and period of record flow conditions for Susitna River at Gold Creek (PRM 140.0).
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Figure 22. Primary riparian cross section at FA-115 (Slough 6A) showing location of groundwater wells, surface-water
measurement locations, and the measured water levels on April 24-25, 2014, with inferred water table.
Figure 23. Groundwater elevations and surface-water levels for selected stations in FA-115 (Slough 6A) representing
upland groundwater conditions and lower groundwater wells affected by riverine processes.
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Figure 24. Primary riparian cross section at FA-138 (Gold Creek) showing locations of surface-water measurement
locations, and typical upland features that indicate shallow groundwater conditions. Water levels are shown for the cross-
section survey date of 9/14/2014.
Figure 25. Surface-water levels for stations in the FA-138 (Gold Creek) riparian transect. Major hydrologic periods are
indicated to show how the variation in water levels relate to the climate and hydrologic processes relevant to these
periods.
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Figure 26. Cross-section profile of the Upper Riparian Transect in FA-128 (Slough 8A) showing the land surface profile,
location of groundwater wells and surface water measuring points on Upper Side Channel 8A and Slough 8A. Water
levels are shown for the April 20-23, 2014. Water levels in Upper Side Channel 8A are ice affected.
Figure 27. Water level data for Upper Side Channel 8A, Slough 8A, and groundwater wells between the two surface-
water features on the Upper Riparian Transect in FA-128 (Slough 8A).
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Figure 28. Hydrologic terrain examples for mountainous terrain and local-scale hyporheic scale processes (Winter 1998).
Figure 29. Hydrologic terrain examples for riverine terrain and local-scale floodplain processes (Winter 1998).
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Figure 30. Conceptual groundwater and surface water processes on a valley transect at FA-138 (Gold Creek) at a valley
scale.
Figure 31. Conceptual groundwater and surface water processes on a valley transect at FA-138 (Gold Creek) at a broad
floodplain scale showing adjacent older terraces.
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Figure 32. Conceptual groundwater and surface water processes on a valley transect at FA-138 (Gold Creek) at a narrow
floodplain scale showing relationships of river levels, shallow water tables in the floodplain and seepage faces at slope
breaks where springs are commonly seen.
Figure 33. Aerial images of the terrain hydrology and riparian cover at FA-138 (Gold Creek) located on the right bank
(looking downstream). Images were taken August 22, 2013. (a) Shows the general location of the FA-138 Riparian
transect, which goes from the edge of the Susitna River across the upland terrace and crosses abandoned sloughs and
beaver ponds that are against the hill slope. (b) View of the abandoned beaver pond, developed in an old slough. (c) View
of an abandoned slough, adjacent and above the Susitna River.
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Figure 34. Secondary riparian cross section at FA-115 (Slough 6A) showing location of surface-water measurement
locations and the measured water levels on April 24-25, 2014 with inferred water table. This transect is an example
transect for applying lateral hydraulic gradients within a Focus Area.
Figure 35. Primary Riparian Cross Section at PRM-112 (Project River Mile). This transect is an example transect for
applying lateral hydraulic gradients outside a Focus Area.
Figure 36. Secondary Riparian Cross Section at PRM-112 (Project River Mile). This transect is an example transect for
applying lateral hydraulic gradients outside a Focus Area.
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Figure 37. Primary riparian cross section at FA-115 (Slough 6A) showing location of groundwater wells, surface-water
measurement locations, and the measured water levels on April 24-25, 2014 with inferred water table and the associated
lateral hydraulic gradient diagram showing the hydrologic features for defining hydrology characteristics in terms of
lateral hydraulic gradients.
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APPENDIX A. HYDROLOGIC STATIONS PRIMARY STATION
PURPOSE, LOCATION AND DATA COLLECTION PARAMETERS
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Table 1. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-144 (Slough 21).
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Table 2. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-141 (Indian River).
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Table 3. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-138 (Gold Creek).
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Table 4. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-128 (Slough 8A).
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Table 4. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-128 (Slough 8A), continued.
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Table 5. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-115 (Slough 6A).
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Table 6. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-113 (Oxbow 1).
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Table 7. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
PRM 112 (Slough 6).
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Table 8. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-104 (Whiskers Slough).
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