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Home My WebLink AboutSuWa14Alaska Resources Library & Information Services Susitna-Watana Hydroelectric Project Document ARLIS Uniform Cover Page Title: Development of sediment-transport relationships and an initial sediment balance for the middle and lower Susitna River segments SuWa 14 Author(s) – Personal: Author(s) – Corporate: Prepared by Tetra Tech, Inc. AEA-identified category, if specified: March 01, 2013 Filing AEA-identified series, if specified: Series (ARLIS-assigned report number): Susitna-Watana Hydroelectric Project document number 14 Existing numbers on document: Published by: [Anchorage, Alaska : Alaska Energy Authority, 2013] Date published: February 2013 Published for: Prepared for Alaska Energy Authority Date or date range of report: Volume and/or Part numbers: Attachment H Final or Draft status, as indicated: Document type: Report Pagination: v, 39, 45 p. Related work(s): Cover letter (SuWa 6), Attachments A-G, I (SuWa 7-12, 15) Pages added/changed by ARLIS: Added cover letter Notes: All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS- produced cover page and an ARLIS-assigned number for uniformity and citability. All reports are posted online at http://www.arlis.org/resources/susitna-watana/ March 1, 2013 Ms. Kimberly D. Bose Secretary Federal Energy Regulatory Commission 888 First Street, NE Washington, DC 20426 Re: Susitna-Watana Hydroelectric Project, FERC Project No. 14241-000; Filing of 2012 Baseline Environmental and Resources Study Reports Dear Secretary Bose: As explained in its Pre-Application Document and Revised Study Plan (RSP) for the proposed Susitna-Watana Hydroelectric Project, FERC Project No. 14241 (Project), the Alaska Energy Authority (AEA) carried out numerous baseline environmental and resources studies related to the proposed Project during the 2012 field season. Because the 2012 studies occurred prior to the commencement of the study phase of the licensing effort under the Federal Energy Regulatory Commission’s (Commission) Integrated Licensing Process, AEA was not required to complete these baseline studies. However, AEA voluntarily undertook these studies for purposes of taking advantage of the 2012 field season to gather environmental data related to the proposed Project, and to help inform the scope and methods of the licensing studies during 2013-14, as set forth in AEA’s RSP. As AEA has completed the study reports associated with these 2012 baseline environmental and resources studies, it has made the study reports publicly available by uploading them to the “Documents” page of its licensing website, http://www.susitna- watanahydro.org/type/documents/. The purpose of this filing is to submit these study reports to the Commission’s record for the above-referenced Project. In particular, the following study reports are attached, all of which are relevant to the Commission’s study plan determination scheduled for April 1, 2013: • Attachment A: Adult Salmon Distribution and Habitat Utilization Study (January 2013) • Attachment B: Synthesis of Existing Fish Population Data (February 2013) • Attachment C: Mercury Assessment and Potential for Bioaccumulation (February 2013) 2 • Attachment D: Technical Memorandum, Susitna River Large Woody Debris Reconnaissance (March 2013) • Attachment E: Riparian Vegetation Study Downstream of the Proposed Susitna-Watana Dam (February 2013) • Attachment F: Technical Memorandum, Reconnaissance Level Assessment of Potential Channel Change in the Lower Susitna River Segment (February 2013) • Attachment G: Stream Flow Assessment (February 2013) • Attachment H: Development of Sediment-Transport Relationships and an Initial Sediment Balance for the Middle and Lower Susitna River Segments (February 2013) • Attachment I: Technical Memorandum, Initial Geomorphic Reach Delineation and Characterization, Middle and Lower Susitna River Segments (February 2013) As the remaining 2012 study reports are finalized, AEA will continue to update its website and submit them to the record. If you have questions concerning this submission, please contact me at wdyok@aidea.org or (907) 771-3955. Sincerely, Wayne Dyok Project Manager Alaska Energy Authority Attachments cc: Distribution List (w/o Attachments) Attachment H Development of Sediment-Transport Relationships and an Initial Sediment Balance for the Middle and Lower Susitna River Segments (February 2013) Susitna-Watana Hydroelectric Project (FERC No. 14241) Development of Sediment-Transport Relationships and an Initial Sediment Balance for the Middle and Lower Susitna River Segments Prepared for Alaska Energy Authority Prepared by Tetra Tech February 2013 REPORT SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page i February 2013 TABLE OF CONTENTS Summary .........................................................................................................................................v 1. Introduction ........................................................................................................................1 2. Study Objectives.................................................................................................................2 3. Study Area and Available Data ........................................................................................2 4. Methods ...............................................................................................................................4 4.1. Deviations from Study Plan .....................................................................................4 4.2. Sediment Load Rating Curves .................................................................................4 4.3. Bias Correction and Annual Load Estimates ...........................................................5 5. Results .................................................................................................................................6 5.1. Pre-Project................................................................................................................6 5.2. Maximum Load Following Operation Scenario 1 ...................................................7 6. Discussion and conclusions ...............................................................................................9 7. References .........................................................................................................................14 8. Tables ................................................................................................................................16 9. Figures ...............................................................................................................................22 LIST OF TABLES Table 3.0-1. List of streamflow gages. .......................................................................................17 Table 3.0-2. Sediment-transport data summary .........................................................................18 Table 4.1-1 Summary of sediment load relationships used for the analysis. ............................19 Table 6.0-1. Comparison of average annual sediment loads under pre-Project conditions. ......20 Table 6.0-2. Comparison of average annual sediment loads under Maximum Load Following OS-1 conditions. ...................................................................................21 REPORT SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page ii February 2013 LIST OF FIGURES Figure 3.0-1. Susitna River study area and large-scale river segments. ..........................................23 Figure 5.1-1. Estimated annual silt/clay, sand and gravel loads at the Gold Creek (Gage No. 15292000)/, Susitna River near Talkeetna (Gage No. 15292100) gage over the 61- year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years. .....................................................................................24 Figure 5.1-2. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Sunshine (Gage No. 15292780) gage over the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years. ................25 Figure 5.1-3. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Susitna Station (Gage No. 15294350) gage over the 61-year period of flows under pre- Project conditions. Also shown is the annual flow volume for each of the years. ...26 Figure 5.1-4. Estimated annual silt/clay, sand and gravel loads at the Chulitna River near Talkeetna (Gage No. 15292400), Chulitna River below Canyon near Talkeetna (Gage No. 15292410) gage over the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years. ................27 Figure 5.1-5. Estimated annual silt/clay, sand and gravel loads at the Talkeetna River near Talkeetna (Gage No. 15292700) gage over the 61-year period of flows under pre- Project conditions. Also shown is the annual flow volume for each of the years. ...28 Figure 5.1-6. Estimated annual silt/clay, sand and gravel loads at the Yentna River near Susitna Station (Gage No. 15294345) gage over the 61-year period of flows under pre- Project conditions. Also shown is the annual flow volume for each of the years. ...29 Figure 5.1.7. Average annual silt/clay, sand and gravel loads under pre-Project conditions for the three mainstem gages and three major tributary gages considered in the analysis. ......................................................................................................................30 Figure 5.2-1. Estimated annual silt/clay, sand and gravel loads at the Gold Creek (Gage No. 15292000), Susitna River near Talkeetna (Gage No. 15292100) gage over the 61- year period of flows under Max LF OS-1conditions. Also shown is the annual flow volume for each of the years. .............................................................................31 Figure 5.2-2. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Sunshine (Gage No. 15292780) gage over the 61-year period of flows under Max LF OS- 1conditions. Also shown is the annual flow volume for each of the years. ..............32 Figure 5.2-3. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Susitna Station (Gage No. 15294350) gage over the 61-year period of flows under Max LF OS-1conditions. Also shown is the annual flow volume for each of the years. ..33 Figure 5.2.4. Average annual silt/clay, sand and gravel loads under Maximum Load Following OS-1 conditions for the three mainstem gages and three major tributary gages considered in the analysis. Note that the tributary loads are the same as pre- Project conditions. .....................................................................................................34 Figure 6.0-1. Average annual silt/clay loads at the three mainstem gages and the three primary tributary gages under pre-Project and Maximum Load Following OS-1 conditions. 35 REPORT SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page iii February 2013 Figure 6.0-2. Average annual sand loads at the three mainstem gages and the three primary tributary gages under pre-Project and Maximum Load Following OS-1 conditions. ..................................................................................................................36 Figure 6.0-3. Average annual gravel loads at the three mainstem gages and the three primary tributary gages under pre-Project and Maximum Load Following OS-1 conditions. ..................................................................................................................37 Figure 6.0-4. Average annual sand loads at the mainstem and tributary gages, along with the estimated annual sand load from ungaged tributaries, under pre-Project and Maximum Load Following OS-1 conditions. Also shown is the accumulated sediment supply to key points along the reach based on the gaged and ungaged sand loads. ..................................................................................................................38 Figure 6.0-5. Average annual gravel loads at the mainstem and tributary gages, along with the estimated annual gravel load from ungaged tributaries, under pre-Project and Maximum Load Following OS-1 conditions. Also shown is the accumulated sediment supply to key points along the reach based on the gaged and ungaged gravel loads. ...............................................................................................................39 APPENDICES Appendix A: Sediment-transport Data and Regression Summary Appendix B.1: Annual Sediment Load Tabular Summary for pre-Project Conditions Appendix B.2: Annual Sediment Load Tabular Summary for Maximum Load Following Operations Scenario 1 REPORT SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page iv February 2013 LIST OF ACRONYMS AND SCIENTIFIC LABELS Abbreviation Definition AEA Alaska Energy Authority cfs cubic feet per second FERC Federal Energy Regulatory Commission ILP Integrated Licensing Process M million mm millimeter MVUE Minimum Variance Unbiased Estimator NEPA National Environmental Policy Act NGVD National Geodetic Vertical Datum NWIS National Water Information System OS Operation Scenario PRM Project River Mile RM River Mile RSP Revised Study Plan sq mi square mile USGS U.S. Geological Survey WY Water Year REPORT SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page v February 2013 SUMMARY The purpose of the study effort was to make preliminary estimates of the overall sediment balance in the Middle and Lower River segments under pre-Project conditions and the potential magnitude of the changes that will occur under Maximum Load Following Operating Scenario (OS)-1 hydrologic conditions. A sediment balance is the determination of the difference between the inflowing sediment (supply) to a reach and the outflowing sediment from the reach (transport). If the sediment inflow to the reach is greater than the outflow, then sediment is stored within the reach. If the sediment supply into the reach is less than the sediment outflow from the reach, then sediment is removed from the reach. In the former case, the reach is considered depositional and in the latter case it is considered aggradational. If the sediment inflow and outflow are nearly equal, the reach is considered in balance with its sediment supply and transport. Sediment transport relationships were developed at three locations on the mainstem Susitna River, Gold Creek, Sunshine and Susitna Station, and on its three largest tributaries, the Chulitna, Talkeetna and Yentna Rivers. Since the ability of the river to transport sediment and its response to the sediment being supplied varies greatly with the size of the sediment, relationships were developed for three sizes of sediment, wash load (silts and clay), sand load and gravel load. The relationships were applied to the long term hydrologic conditions represented by the Pre- Project and Maximum Load Following OS-1 scenarios. The sediment balance was computed for both conditions for the portion of the Susitna River from the Watana dam site to the Susitna Station gage approximately 30 miles upstream of the river’s mouth. The sediment transport relationships developed in the 2012 effort will be used in the 2013 and 2014 Geomorphology Studies to support detailed 1-D and 2-D bed evolution modeling of the Susitna River below Watana Dam. The relationships supported the assessment of 2012 study Reconnaissance Level Assessment of Potential Channel Change in the Lower Susitna River Segment. The sediment transport relationships may be updated based on comparison with data collected by the U.S. Geological Survey (USGS) in 2012 and additional data to be collected in 2013. For most of the Susitna River above Susitna Station, the gravel load plays the most significant role in determining the river’s morphology. Under Maximum Load Following OS-1 conditions, the average annual gravel load at Sunshine will decrease to about 140,000 tons; thus, the total gravel supply above Susitna Station will decrease to about 370,000 tons/year. Based on integration of the gravel load rating curve over the Maximum Load Following OS-1 flow record, the average annual gravel load at Susitna Station would decrease to about 200,000 tons. This indicates that the reach between Sunshine and Susitna Station would remain aggradational, but the relative imbalance in gravel loads would decrease by about one-third from an excess of 250,000 tons under pre-Project conditions to about 170,000 tons under Maximum Load Following OS-1 conditions. Review of USGS data and the results of the sediment balance also indicated that at Susitna Station, the sand load may be the dominant factor in determining the morphology of the river. Sufficient information is not available at this time to identify the location of the transition zone from gravel to sand dominance, and specifically whether this occurs above or below the Yentna River confluence. This determination will be important in understanding potential Project effects. The 1-D sediment-transport modeling to be conducted in 2013 between Sunshine and Susitna Station will be a key tool in making these assessments. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 1 February 2013 1. INTRODUCTION The Alaska Energy Authority (AEA) is preparing a License Application that will be submitted to the Federal Energy Regulatory Commission (FERC) for the Susitna-Watana Hydroelectric Project (Project) using the Integrated Licensing Process (ILP). The Project is located on the Susitna River, an approximately 300-mile-long river in the Southcentral Alaska. The Project’s dam site would be located at Project River Mile (PRM) 187.1. The results of this study will provide information that will inform the 2013–2014 formal study program, and Exhibit E of a license application, and FERC’s National Environmental Policy Act (NEPA) analysis for the Project license. The G-S4: Reconnaissance-level Geomorphic and Aquatic Habitat Assessment of Project Effects on Lower River Channel study plan includes, among other objectives, a preliminary evaluation of the relative magnitude of changes in the sediment regime associated the Susitna-Watana Hydroelectric Project. This memorandum summarizes work performed under the Sediment Load Comparison section of the Sediment Transport Assessment task to meet this objective, including the development of sediment-transport relationships using the available sediment-transport data, and an initial sediment balance for the Middle and Lower Susitna River segments, based on the pre-Project hydrology and post-Project hydrology under an operations scenario referred to as Maximum Load Following Operation Scenario 1 (OS-1). These two hydrology scenarios were analyzed in detail in Tetra Tech (2013a). The pre-Project analysis was performed for six streamflow gages located in the Susitna Basin using 61 years of extended hydrologic records developed by the U.S. Geological Survey (USGS 2012) for the period from Water Year (WY) 1950 through WY2010. Three of the gages are located on the mainstem Susitna River and three of the gages are located on major tributaries (the Chulitna, Talkeetna and Yentna Rivers). The Maximum Load Following OS-1 hydrology is a simulated flow record developed with the Project-conditions flow-routing model (MWH 2012) for the same 61-year period as the pre- Project records. Maximum Load Following OS-1 is based on the assumption that the load fluctuation of the entire Railbelt would be provided by the Project, and all other sources of electrical power in the Railbelt would be running at base load. This assumed condition is not realistic for an entire year, and the results of this condition should be conservative with respect to assessing downstream impacts of load following. The main components of the sediment-transport analysis include the following:  A review of previously published relationships between discharge and (1) suspended sediment load, (2) bed load, and (3) total sediment load (Knott et al. 1987), and refinement of those relationships where additional data were available.  Application of selected relationships to both the pre-Project and Maximum Load Following OS-1 flow records to estimate annual sediment loads for suspended silt/clay (i.e., wash load), total sand load based on independent estimates of the amount of sand being carried in suspension and as bed load, and the gravel component of the bed load.  Comparison of the estimated annual sediment loads to provide an approximate sediment balance in the river reaches between the mainstem gages in the Middle and Lower Rivers. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 2 February 2013 2. STUDY OBJECTIVES The overall objective of this memorandum is to make preliminary estimates of the overall sediment balance in the Middle and Lower River segments under pre-project conditions and the potential magnitude of the changes that will occur under Maximum Load Following OS-1 hydrologic conditions, including the specific assessments of the following, interrelated topics:  Determination of the suitability of previously published sediment transport relationships between discharge and sediment load and update the relationships if necessary.  Selection of the most appropriate sediment transport relationships for use in the preliminary sediment balance.  Use the selected sediment transport relationships to estimate the pre-Project and Maximum Load Following OS-1 annual loads. The sediment loads will be divided into wash load (silt and clay), sand load and gravel load.  Comparison of estimated annual sediment loads at the three mainstem Susitna River gages to characterize the overall sediment balance under pre-Project conditions and the potential changes under Maximum Load Following OS-1 conditions. A sediment balance is the determination of the difference between the inflowing sediment (supply) to a reach and the outflowing sediment from the reach (transport). If the sediment inflow to the reach is greater than the outflow, then sediment is stored within the reach. If the sediment supply into the reach is less than the sediment outflow from the reach, then sediment is removed from the reach. In the former case, the reach is considered depositional and in the latter case it is considered aggradational. If the sediment inflow and outflow are nearly equal, then the reach is considered in balance or in equilibrium in terms of sediment supply and transport. 3. STUDY AREA AND AVAILABLE DATA The Susitna River, located in Southcentral Alaska, drains an area of approximately 20,010 square miles and flows about 320 miles from its headwaters at the Susitna, West Fork Susitna and East Fork Susitna glaciers to the Cook Inlet (USGS 2012). The Susitna River basin is bounded on the west and north by the Alaska Range, on the east by the Talkeetna Mountains and Copper River Lowlands and on the south by Cook Inlet. The highest elevations in the basin are at Mt. McKinley at 20,320 feet while its lowest elevations are at sea level where the river discharges into Cook Inlet. Major tributaries to the Susitna River between the headwaters and Cook Inlet include the Chulitna, Talkeetna and Yentna Rivers that are also glacially fed in their respective headwaters. The basin receives, on average, 35 inches of precipitation annually with average annual air temperatures of approximately 29oF. There are 14 USGS streamflow gages located in the Susitna River Basin plus one on the Little Susitna River that was used as an index station (Table 3.0-1 and Figure 3.0-1). The period of recorded data available for these gages ranges from 58 years at the Gold Creek gage to less than 10 years at gages such as the Yentna River at Susitna Station and the Susitna River at Sunshine gages. The data available from many of these gages may not adequately represent long-term streamflow conditions in the Susitna River Basin because of the short period of record and the distribution of years during which data were collected (USGS 2012). To provide a consistent SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 3 February 2013 long-term record, the USGS extended the record of 11 of these gages to 61 years (WY1950 – WY2010). WY1950 was selected for the start of the record because this was the first full water year of data collection for the primary index station at Gold Creek. The Montana Creek (Mont), Deception Creek (Decep), and the Deshka River (Desh) gages were not included in the extended record analysis because they could not be adequately correlated to any long-term index station for the entire study period (USGS 2012). Three main stem gages and three primary tributary gages locations downstream of the Project site PRM 187.1 (Figure 3.0-1) were used to characterize the sediment-transport regime under the 61-year hydrology record for each portion of the reach, as follows:  Main Steam Gages o Middle River Mainstem: Susitna River at Gold Creek Gage (15292000) and Susitna River near Talkeetna Gage (15292100)1 o Lower River mainstem below Three Rivers Confluence: Susitna River at Sunshine Gage (15292780) o Lower River mainstem below Yentna River: Susitna River at Susitna Station Gage (15294350)  Primary Tributary Gages o Tributary Supply to Three River Confluence (Chulitna River near Talkeetna Gage (15292400) and the Chulitna River below canyon near Talkeetna gage (15292410)1) o Talkeetna River near Talkeetna Gage (15292700) o Tributary Supply to Lower River: Yentna River near Susitna Station Gage (15294345) The number and types of sediment samples, and the dates of sampling vary among the gages, but generally include both the magnitude and gradation of the suspended sediment and bed load for samples collected between the late-1970s and the late-1980s (Table 3.0-2). The bulk of these data that were collected through WY1985 were previously analyzed by Knott et al. (1987). As part of the current analysis, the available data for each of the gages were downloaded from the USGS National Water Information System (NWIS) website (http://waterdata.usgs.gov), and relevant data collected after 1985 were added to the data sets. The post-Project hydrologic conditions of the Chulitna, Talkeetna and Yentna Rivers would be unaffected by the Maximum Load Following OS-1 condition; thus, the post-Project sediment supply from tributaries were assumed to be equivalent to the pre-Project supply. 1 Data from both these gages were combined into a single data set for the USGS (1987) analysis; this approach was adopted for this preliminary study, as well. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 4 February 2013 4. METHODS This section describes the methods used to select or develop relationships between discharge and sediment load for each component of the sediment load at the six USGS gaging stations, and apply these relationships, with the minimum variance unbiased estimator (MVUE) bias- correction technique, to the pre-Project and Maximum Load Following OS-1 extended flow records to estimate the annual sediment loads for each size range. 4.1. Deviations from Study Plan The Study Plan calls for comparison of the total sediment load at the Sunshine and Susitna Station gaging stations for an average, wet, and dry year between pre-Project and adjusted post- Project conditions using adjusted post-Project rating curves. Because the 61-year daily flow record was available for pre-Project and Maximum Load Following OS-1 conditions, the full record was used for this purpose in lieu of selecting specific years for the analysis, with sediment loads compared on an average annual basis over all years, and the variability assessed by considering the range of annual loads from the 61-year record. This more comprehensive approach to assessing sediment loads provides a better assessment of the long-term project influence on sediment transport than considering only the three “representative” years. 4.2. Sediment Load Rating Curves Knott et al. (1987) used the data collected through WY1985 at the six gages to characterize sediment-transport conditions in the reach. This included development of relationships between discharge and sediment loads from data for four components of the total sediment load collected during the period between October 1984 and September 1985, data collected from WY1981 through WY1984, and historical records (USGS 1953 to 1980):  Suspended silt/clay  Suspended sand  Sand bed load,  Gravel bed load The Knott et al. (1987) relationships were of the power-function form: 𝑄𝑠=𝑎(𝑄)𝑏 (4.2-1) where: Qs = sediment load (tons/day) a = coefficient b = exponent Q = discharge (cubic feet/second) For consistency with Knott et al. (1987) and standard practice in developing sediment load rating curves (USGS, 1992), power function relationships were also used for the current study. As an initial step in the analysis, the available data through WY1985 in each size-range at each of the gages was plotted and compared with the data plots in Knott et al. (1987). This comparison revealed a limited number of available data points from the NWIS database that SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 5 February 2013 were not used in the Knott et al. (1987) analysis. No explanation was provided in their report for why these data points were not used. In an attempt to ascertain the reason(s), Mr. Gary Solin at the USGS Alaska Science Center, where the original data collection and analysis were performed, was contacted. Mr. Solin indicated that the individuals who performed the analysis were either retired and out of contact; thus, he was not able to provide specific information about the issue. He did, however, suggest that the data points used in the analysis were probably limited to those directly collected by the study team and/or for which the study team had specific knowledge. Based on this information, the decision was made to limit the WY1985 and earlier data to those data points used by Knott et al. (1987), under the assumption that their study team had the best knowledge of the quality and relevance of the data at that time; thus, their dataset represents the best-available data through WY1985. After identifying the data points used by Knott et al. (1987), the data sets were updated by adding relevant data collected since WY1985. Power-function regression lines were then fit to the extended data sets using the least-squares regression technique and compared to the Knott et al. (1987) line-of-best-fit. Through analysis and inspection of the data and knowledge of the range of typical exponents for the different components of the sediment load, either the USGS line-of-best fit or the new regression equations were selected for this preliminary study (Table 4.1-1 and Appendix A). With the exception of the silt/clay load for the Gold Creek/near Talkeetna data set, new regression equations were developed for all of the suspended sediment loads to incorporate the post-WY1985 data points. The USGS equation was used for the Gold Creek/near Talkeetna data set because the new regression line significantly over-predicts the loads at flows less than about 20,000 cfs. It appears that Knott et al. (1987) also recognized this issue and visually fit a line to the data that provided better fit to data over the full range of discharges. Because of the significant scatter in the data and the typically limited range of flows over which the data were collected, regression equations do not provide reasonable relationships for most of the bed-load data sets. For this reason, the USGS equations were adopted for all of the data sets except for those at Susitna Station. Partly because of the influence of five newer sand bed load and three newer gravel bed load data points that were collected in 2003, the regression equations for both appear to fit the data better than the USGS equations, and the regression equations were, thus, used for both components of the bed load at this site. 4.3. Bias Correction and Annual Load Estimates The selected relationships between discharge and the various components of the sediment load were then used with the MVUE bias-correction technique to estimate daily sediment loads for the entire 61-year record of mean daily flows for both pre-Project and Maximum Load Following OS-1 conditions. The MVUE technique was used to correct for the statistical bias that occurs in basic power-function regression, based guidance from USGS (1992). Previous studies have demonstrated that the bias occurs in the process of linearizing the data set by transforming it into the logarithmic domain and then back-transforming the resulting relationship into the arithmetic domain (Walling 1977b; Thomas 1985; Ferguson 1986). Various procedures are available to address the bias, including accounting for seasonal differences in sediment transport and accounting for hysteresis related to rising and falling limbs of flood hydrographs (Guy 1964; Walling 1974). Koch and Smillie (1986) and Cohn and Gilroy (1991) described methods of numerically correcting for the bias that depend on the expected distribution of errors. USGS (1992) endorsed the recommendations in Cohn and Gilroy (1991) to use the MVUE bias SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 6 February 2013 correction for normally distributed errors, or the Smearing Estimator (Duan 1983) when a non- normal error distribution is identified. The MVUE method was selected in this analysis to remove the bias from the log-transformed sediment loads because the errors are generally normally-distributed. Annual sediment loads for each year in the pre-Project and Maximum Load Following OS-1 records were developed by summing the bias-corrected daily sediment loads. 5. RESULTS This section summarizes the annual sediment yields developed using the methods described in Section 4 for the pre-Project and Maximum Load Following OS-1 conditions at the three main stem gages and three primary tributary gages. As noted above, Knott et al. (1987) divided the total sediment load into four components, primarily because of the manner in which the data are collected. It is, however, more meaningful from a river-process perspective to re-group these components into three components, consisting of the wash load (i.e., silt/clay that is almost exclusively carried in suspension), the sand component of the bed material load that consists of the sand that is carried both in suspension and as bed load, and the gravel component of the bed load. The sand load is being treated separately in this analysis because it may be strongly supply-limited, and thus more correctly categorized as part of the wash load in the Middle River and tributaries; however, in the Lower River in the area of Susitna Station and further downstream, the sand load may be transport limited. 5.1. Pre-Project Under pre-Project conditions, the estimated total annual sediment loads at the Gold Creek/near Talkeetna gage average about 3.3 million (M) tons, varying from about 550,000 tons to nearly 11M tons (Figure 5.1-1). Of these amounts, the silt/clay, wash load accounts for about 55 percent (1.8M tons) of the total, on average, while the sand accounts for about 43 percent (1.4M tons) and the gravel bed load accounts for only about 2 percent (66,000 tons) of the total. At the Sunshine gage, the average, pre-Project total annual sediment load increases to about 16.4M tons, ranging from about 4.7M to 26.8M tons (Figure 5.1-2). The relative proportion of wash load increases to about 61 percent (10.0M tons) of the total, with the sand and gravel loads accounting for about 37 and 1.7 percent (6.1M and 280,000 tons) of the total, respectively. The annual total load at the Susitna Station gage averages about 34.1M tons, and ranges from 18.3M to 53.1M tons (Figure 5.1-3). The silt/clay load accounts for about 57 percent (19.5M tons), and the sand and gravel loads account for about 42 percent (14.3M tons) and less than 1 percent (260,000 tons) of the total, respectively, at this location. The three primary tributaries supply a significant amount of the sediment to the mainstem. The annual load from the Chulitna River, for example, averages about 9.9M tons, ranging from 4.8M tons to 24.7M tons (Figure 5.1-4), and the Talkeetna River supplies an average of about 1.9M tons/year, ranging from about 380,000 to 6.9M tons/year (Figure 5.1-5). The Yentna River carries the largest total load of the three, averaging about 15.5M tons/year and ranging from 6.7M to 31.5M tons/year (Figure 5.1-6). The Chulitna River delivers a much larger percentage of gravel than either the mainstem or the other two major tributaries (about 7.5 percent versus 3.1 and 1.2 percent for the Talkeetna and Yentna Rivers, respectively). The Yentna River delivers SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 7 February 2013 the smallest relative percentage of wash load of the three tributaries (48 percent versus 53 and 50 percent for the Chulitna and Talkeetna Rivers, respectively). Based on these results, the Middle River supplies about 22 percent of the total sediment load to the Three Rivers Confluence, and the Chulitna and Talkeetna Rivers supply about 66 and 12 percent of the total load, respectively (Figure 5.1-7). On a by-size-fraction basis, the relative contributions of silt/clay and sand are about the same as the total load; however, the Chulitna River supplies the bulk of the gravel load that is key to the channel morphology (about 86 percent of the total, compared to about 8 percent from the Middle River and 7 percent from the Talkeetna River). The total sediment load from the Yentna River represents about 46 percent of the total load at Susitna Station, and about 65 percent of the gravel load. A tabulation of the estimated annual loads under pre-Project conditions for each component of the load at each of the six gages is provided Appendix B.1. 5.2. Maximum Load Following Operation Scenario 1 Watana Dam and Reservoir will trap a significant percentage of the sediment supply to the Middle River. For purposes of this preliminary analysis, it is assumed that the trap efficiency for the silt/clay load will be on the order of 90 percent, and all of the sand and coarser sediment will be trapped. In addition to the effects on sediment supply, the dam will also modify the flow regime in the downstream river in a manner that will affect the transport capacity along the reach. Tetra Tech (2013a) evaluated the changes in flow regime in the Middle and Lower River associated with Maximum Load Following OS-1 conditions that are based on the very conservative assumption that the load fluctuation of the entire Railbelt would be provided by the Susitna-Watana Project, and all other sources of electrical power in the Railbelt would be running at base load. Under these conditions, the total volume of flow will be essentially the same as under pre-Project conditions on an annual basis, but the distribution throughout the year will change, with a general increase in the winter base flows and decrease in the summer high flows. The effects are most significant in the Middle River, where tributary inflows are relatively small compared to the mainstem flows. The effects diminish significantly downstream from the Three Rivers Confluence due to the relatively large inflows from the Chulitna and Talkeetna Rivers, and they continue to diminish in the downstream direction as the relative contribution from local tributaries increases. Because of the nonlinear relationship between discharge and sediment-transport rates, the changes in flow regime associated with the Project will result in a general decrease in the capacity of the river to transport sediment in each segment of the reach. Based only on the changes in flow regime (i.e., not accounting for the effects of sediment trapping the reservoir), the total sediment load at the Gold Creek/near Talkeetna gage would decrease to about 502,000 tons on an average annual basis, about 285,000 tons of which would be suspended silt/clay, 213,000 tons would be sand, and only about 4,400 tons would be in the gravel size-range (Figure 5.2-1). The supply of gravel from the tributaries between Watana Dam and Gold Creek/near Talkeetna gage is 11,000 tons if it is assumed to be in proportion with the intervening drainage area. If this assumption is reasonable, then gravel materials would tend to accumulate as fans at the mouths of the tributaries and within this reach or river. This amount could be more or less and will be investigated further. Because the bulk of the suspended silt/clay load is derived from upstream of the Watana Dam site, the trap efficiency of the reservoir will directly impact this component of the load throughout the Middle River SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 8 February 2013 immediately upon closure of the dam. Based on the preliminary estimate of 90 percent trap efficiency, and considering the estimated 117,000 tons contributed by the tributaries between the dam site and the gage, the average annual suspended silt/clay load at Gold Creek would, therefore, likely decrease to about 285,000 tons/year, an approximately 84-percent reduction from pre-Project conditions. The relative contribution of the river upstream from the dam site to the sand load, compared to the contributions from within the channel and the intervening tributaries is not known at this time, but it is likely that the upstream contribution represents a relatively significant percentage of the total. During the initial period of a few to several years after closure of the dam, the average annual sand load passing the Gold Creek/above Talkeetna gage will likely be on the order of the 320,000 tons estimated using the pre-Project sand transport rating curves with the Maximum Load Following OS-1 flows, an approximately 77-percent reduction from pre-Project conditions. Based on these estimates, the year-to-year variability would range from only about 88,000 tons to about 1.3M tons. As the supply of sand that is available from the Middle River channel is depleted, the sand load in the vicinity of the Gold Creek/near Talkeetna gage will diminish relatively rapidly to a value that is consistent with the sand load from the intervening tributaries, or about 213,000 tons/year, an approximately 85-percent reduction from pre-Project conditions. The gravel load at Gold Creek/near Talkeetna will likely remain at about the estimated 4,400- tons/year value for a significant period of time because of the slower overall response of gravel- sized material between the dam site and the gage. If the annual supply from the intervening tributaries is less than 4,400 tons then the response will be slow because of the relatively large reservoir of gravel-sized material between the dam site and the gages. If the annual supply is greater than 4,400 tons (preliminary estimate is 11,000 tons), then gradually through time the gravel materials will accumulate and the supply of gravel from the Middle River will tend toward the higher supply rate. The 4,400 tons/year represents an approximately 93-percent reduction from pre-Project conditions. Based on integration of the pre-Project gravel transport curve over the Maximum Load Following OS-1 flow record, the annual gravel loads would vary from about 50 to 42,300 tons on a year-to-year basis. The total sediment load at Sunshine would diminish to about 13.6M tons on an average annual basis under Maximum Load Following OS-1 conditions, of which about 8.5M tons would be suspended silt/clay, 5.0M tons would be sand and about 142,000 tons would gravel (Figure 5.2- 2). This represents an approximately 17-percent reduction in the total sediment load and a 15- percent reduction in the silt/clay load compared to pre-Project conditions. The average annual gravel load would diminish to about 142,000 tons, varying from about 67,000 to 377,000 tons on a year-to-year basis. The average annual gravel load represents a 49-percent reduction from pre- Project conditions. Accounting for the effects of silt/clay trapping in the reservoir that would be seen very rapidly throughout the Middle and Lower Rivers, the average annual total load at Susitna Station would decrease to about 31.3M tons, of which about 18.0M tons would be suspended silt/clay (Figure 5.2-3). This represents an 8-percent reduction in both the total and silt/clay load. The effects of sediment trapping in the upstream reservoir on the sand-and-gravel supply to this portion of the lower river would not be seen for a relatively long period of time (likely, the life of the Project); however, as with the upstream gages, the changes in flow regime associated with the Project would change the transport capacities. Based on integration of the pre-Project sand transport SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 9 February 2013 rating curves over the Maximum Load Following OS-1 flows, the total sand load at Susitna Station would decrease to about 13M tons, an approximately 9-percent reduction from pre- Project conditions. The sand loads would vary from about 8.4M to 18.7M tons on a year-to-year basis. Similarly, the gravel loads would decrease to about 207,000 tons, an approximately 20- percent reduction from pre-Project conditions. The gravel loads would vary from 110,000 to 364,000 tons on an average annual basis. Based on these results, the Middle River would supply only about 4 percent of the total sediment load to the Three Rivers Confluence under Maximum Load Following OS-1 conditions, and the Chulitna and Talkeetna Rivers supply about 81 and 15 percent of the total load, respectively (Figure 5.2-4). On a by-size-fraction basis, the contributions of silt/clay from the Middle River would decrease 4 percent of the total. During the initial periods after closure of the dam, the Middle River would supply about 10 percent of the sand load and only about 0.5 percent of the gravel load to the Three Rivers Confluence. The total sediment load from the Yentna River would supply about 48 percent of both the total load and the gravel load to Susitna Station under Maximum Load Following OS-1 conditions. A tabulation of the estimated annual loads under Maximum Load Following OS-1 conditions for each component of the load at each the three mainstem gages is provided Appendix B.2. 6. DISCUSSION The sediment load analyses presented in the previous sections provide a basis for development of a preliminary sediment balance for the Middle and Lower Rivers. The effects of the dam on the sediment balance vary between the silt/clay, sand and gravel loads. As discussed above, the dam would likely cut off at least 90 percent of the silt/clay supply and essentially all of the sand and gravel supply to the head of the Middle River. The effects on all components of the sediment load would diminish in the downstream direction due to contributions from the tributaries and entrainment of material that is currently stored in the channel. The silt/clay load is carried almost exclusively in suspension. As a result, the effects of sediment trapping in the reservoir on downstream silt/clay loads would be felt within a very short time-frame (i.e., on the order of the travel time of the water) throughout the Middle and Lower Rivers after closure of the dam. Considering the estimated contributions from the tributaries between the dam and the Three Rivers Confluence, the silt/clay load at the lower end of the Middle River would be only about 16 percent of the pre-Project loads (Figure 6.0-1). The effects of the dam on the silt/clay load below Three Rivers diminish significantly due to the large contributions from the Chulitna and Talkeetna Rivers. Based on the available information, the loads at Sunshine with the dam in-place would be about 82 percent of the pre-Project loads, and the contributions from the Yentna and other tributaries between Sunshine and Susitna Station cause the effect to diminish even further so that the post-Project silt/clay loads would be about 92 percent of the pre-Project loads at Susitna Station. Even the very large changes in the silt/clay load in the Middle River are not anticipated to have a significant effect on active channel morphology in Middle River, and the smaller downstream changes are even less likely to affect active channel morphology in the Lower River. The significant reduction in the silt/clay load in the Middle River, along with decreased frequency of floodplain inundation, will have an effect on floodplain sedimentation processes. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 10 February 2013 During the initial period after closure of the dam, Project effects on the sand load in the lower part of the Middle River and the Lower River would result primarily from the change in flow regime, because there is currently sand moving through the system and it moves at a much slower rate than the flow. Over time, much of the stored sand will be depleted from the Middle River, and the load just upstream from the Three Rivers Confluence area will be consistent with the supply from the local tributaries. After this occurs, the sand load above the Three Rivers Confluence will be only about 15 percent of the pre-Project load (Figure 6.0-2). Similar to the silt/clay load, sand inflows from the Chulitna and Talkeetna Rivers will decrease the relative impact of the Project, with Maximum Load Following OS-1 sand-load conditions of about 82 percent of the pre-Project loads. Contributions from the Yentna River and other tributaries downstream from Sunshine will increase the sand loads to about 91 percent of the pre-Project loads at Susitna Station. Except for the upstream portion of the Middle River, Project effects on gravel loads will derive primarily from the changes in flow regime. There appears to be a relatively significant supply of gravel and coarser material between the dam site and the Three Rivers Confluence, the local tributaries likely supply a significant amount of gravel to the river, and the response rate of upstream changes in supply will progress downstream relatively slowly compared to the sand. Based strictly on integration of the pre-Project gravel transport curves over the Maximum Load Following OS-1 flows, the gravel loads in the lower part of the Middle River will be only about 7 percent of the pre-Project loads (Figure 6.0-3). Based on the same assumptions, the gravel loads at Sunshine in the upstream portion of the Lower River will be about 51 percent of the pre- Project loads, and this increases to about 80 percent at Susitna Station. The above information was used to develop a preliminary sediment balance for the Lower and Middle Rivers under pre-Project and Maximum Load Following OS-1 conditions (Tables 6.0-1 and 6.0-2). Ungaged tributaries between the Watana Dam site and the Gold Creek gage account for about 16 percent of the total drainage at Gold Creek, and ungaged tributaries between Sunshine and Susitna Station account for about 11 percent of the total drainage area at Susitna Station. Because they may contribute sufficient sediment to the mainstem to affect this balance, estimates of the ungaged tributary sediment inflows were made based on the unit yields of the various size-ranges of sediment from the available data. Based on these very preliminary estimates, the silt/clay load from ungaged tributaries contribute about 120,000 tons/year of silt/clay to the Middle River on an average annual basis, and the ungaged tributaries between Sunshine and Susitna Station contribute about 2.4M tons/year of silt/clay to the Lower River. Assuming that the unit sand yield is approximately the same at the Watana Dam site as it is at the Gold Creek/near Talkeetna gages (~220 tons/mi2/year), the average annual total sand load at the dam site is about 1.2M tons/year. Further assuming that the Middle River is supply limited with respect to the sand loads, the total sand load passing Gold Creek/near Talkeetna is the same as the total upstream supply and the ungaged tributaries in the Middle River deliver about 210,000 tons of sand to the river on an average annual basis. Based on these estimates, the total sand supply to Sunshine from the Middle River and tributaries under pre-Project conditions is about 6.2M tons, which is remarkably similar to the estimated pre-Project sand load at Sunshine, discussed above, of about 6.1M tons (Figure 6.0-4). Assuming that the ungaged tributaries between Sunshine and Susitna Station have unit sand yields that are similar to the ungaged tributaries to the Middle River, these tributaries deliver about 530,000 tons/year of sand to the Lower River. Based on the sum of the Sunshine, Yentna River and ungaged tributary inflows, SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 11 February 2013 the total sand load above Susitna Station is about 14.8M tons/year, very close to the average annual sand load at Susitna Station of 14.3M tons, estimated by integrating the Susitna Station sand-load rating curves over the 61-year pre-Project flow record. Collectively, these results indicate that the Middle and Lower Rivers are in approximate balance with respect to sand loads under pre-Project conditions. Under Maximum Load Following OS-1 conditions, the sand supply to the upstream end of the Middle River will be essentially eliminated. As noted above, the sand loads in the lower part of the Middle River will remain about the same as they are under pre-Project conditions during the early period of Project operations, with the downstream sand loads decreasing over time to a level that is consistent with the tributary inflows as the sand that is currently stored within the mainstem river channel is depleted. After this occurs, the sand supply to the Three Rivers Confluence will diminish to about 5M tons. Since the sand load is most likely supply-limited in this part of the reach, the sand load at Sunshine will decrease to a level consistent with the supply (i.e., ~5M tons/year, on average). The sand supply from the Yentna River and other ungaged tributaries between Sunshine and Susitna Station is estimated to be about 8.7M tons. Considering the 5M ton sand load at Sunshine, the total sand supply above Susitna Station under Maximum Load Following OS-1 is about 13.7M tons. The degree to which the sand load between Sunshine and the Yenta River confluence is supply-limited is not apparent from the available information. Based on the available data, however, the bed material at Susitna Station is primarily sand; thus, the sand load at this location is probably not supply-limited. This means that the quantity of sand transported in this part of the Lower River is controlled primarily by the flows and not by the upstream supply, and the Project effects on the sand load can be estimated by directly integrating the sand- load rating curves over the Project conditions flow record. Based on this integration, the average annual sand load at Susitna Station will decrease to about 13M tons. Considering the uncertainty in the sand-load estimates, the cumulative sand supply above Susitna Station and the load at Susitna Station are essentially the same (13.7M tons versus 13M tons); thus, this part of the reach would likely remain in approximate balance with respect to the sand load under Maximum Load Following OS-1 conditions. Based on the gravel transport curves, the unit gravel load at Gold Creek/near Talkeetna is about 11 tons/mi2/year. Assuming that the unit yields are similar, the average annual gravel load at the dam site is about 56,000 tons under pre-Project conditions and the gravel supply from the ungaged tributaries is about 11,000 tons (Figure 6.0-5). Based on these estimates and the estimated gravel loads from the Chulitna and Talkeetna Rivers presented above, the total gravel supply upstream from Sunshine under pre-Project conditions is about 870,000 tons, compared to the estimated loads at Sunshine of about 280,000 tons. Even considering the uncertainty in the transport relationships, these results strongly indicate that the river is aggradational between the Three Rivers Confluence and Sunshine. This conclusion is supported by the highly braided character of the river in this part of the reach. The gravel loads at Sunshine and the Yentna River from the results in the previous section equate to unit yields of about 27 and 25 tons/ mi2/year, respectively. Assuming that the ungaged tributaries between Sunshine and Susitna Station have similar unit yields, these tributaries deliver approximately 53,000 tons of gravel to the mainstem on an average annual basis. The approximate gravel supply to the lower river from Sunshine, the Yentna River and the ungaged tributaries, therefore, averages about 510,000 tons/year. The average annual gravel load at Susitna Station under pre-Project conditions is about 260,000 tons, SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 12 February 2013 indicating that the portion of the Lower River between Sunshine and Susitna Station is also net aggradational. Similar to the Three Rivers Confluence to Sunshine portion, this result is consistent with the highly braided character of this part of the river. Under Maximum Load Following OS-1 conditions, the average annual gravel load at Sunshine will decrease to about 142,000 tons; thus, the total gravel supply above Susitna Station will decrease to about 375,000 tons/year. Based on integration of the gravel load rating curve over the Maximum Load Following OS-1 flow record, the average annual gravel load at Susitna Station would decrease to about 207,000 tons. This indicates that the reach between Sunshine and Susitna Station would remain aggradational, but the relative imbalance in gravel loads would decrease by about one-third from an excess of 252,000 tons under pre-Project conditions to about 168,000 tons under Maximum Load Following OS-1 conditions. As described in RSP Sections 6.5.4.3 and 6.6, and based on the above results, the following actions will be implemented: 1. New sediment load data that have been collected over the past few years by the USGS will be incorporated into the analysis to improve the sediment-transport rating curves. 2. The USGS will extend their sediment data collection program to include bed load, suspended sediment load, bed material and discharge to include Susitna Station and the Yentna River near Susitna Station to support the recent decision (Tetra Tech 2013b) to extend the 1-D sediment- transport model downstream to Susitna Station (PRM 29). The data from this effort will facilitate comparison with the 1980s data at these locations to check the validity of the earlier data, and it will also expand the data base that is available for development of sediment- transport relationships. 3. The updated sediment-transport rating curves for the mainstem gages will be used to calibrate the sediment-transport rates in the reach-wide 1-D sediment-transport model. 4. In the current analysis, sediment loading from all ungaged sources was lumped into the “ungaged tributary” category. In reality, sediment is also supplied to the river from bank erosion and mass wasting from unstable hillslopes. Estimates of the sediment loading from all of these sources, including the ungaged tributaries, will be segregated and improved based on field observations, evaluation of lateral bankline shifting and bed material measurements and transport capacity calculations in the lower end of a selected number of the larger ungaged tributaries. As described in RSP Section 6.6.4.1.2.6 (AEA 2012), sediment-load rating curves for the ungaged tributaries will be developed by surveying cross sections and collecting bed material samples in an appropriate reach near the mouth, developing 1-D hydraulic conditions using either step-backwater or normal depth calculations, as appropriate, and applying an appropriate bed material transport equations with the measured bed material gradations. For those tributaries that enter the river within the Focus Areas, the hydraulic and sediment-transport analysis to assess the response of the Susitna River channel to Project conditions will be performed using the 2-D model(s). For the selected tributaries outside the focus areas, the analysis will be performed using 1-D hydraulic modeling with relatively closely spaced cross sections in the vicinity of the confluence. 5. The tributary-specific sediment loads estimated in the previous task will be used to assess the potential impact of changes in flow and sediment load in the mainstem on the sediment- transport behavior at the tributary mouths. A key question to be answered by this analysis is SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 13 February 2013 the extent to which the coarse-grained sediment from the tributaries will be entrained and transported downstream away from the tributary mouth versus building of the delta in a manner that could potentially affect fish passage into the tributary and/or constrict the river causing other impacts to water-surface elevations and channel stability. Similar to the sediment loading analysis, the analysis for those tributaries that are located within a Focus Area will be conducted using the 2-D mobile-boundary model. At the selected tributaries outside the Focus Areas, additional mainstem cross sections (typically 5 to 7, in total) will be surveyed in the vicinity of the mouth, and 1-D hydraulic modeling and sediment-transport calculations will used to perform the assessment. 6. Section 6.6.4.1.2.6., Tributary Delta Modeling of the RSP (AEA 2012), indicates that modeling of the sediment-transport dynamics at the Three Rivers Confluence may be necessary to understand the potential effects of Project operations. Based on the initial sediment balance presented above, the total gravel bed-load supply that is key to the behavior of this area would decrease by only about 7 percent from about 871,000 ton/year, on average, to about 810,000 tons/year under Maximum Load Following OS-1 conditions because of the overwhelming contribution from the Chulitna River and the large (relative to Middle River) contribution from the Yentna River. The transport capacity for gravel bed load past the Sunshine gage would decrease by about 50 percent from about 279,000 tons/year to about 142,000 tons/year under Maximum Load Following OS-1 conditions. As a result, the pre- Project gravel excess in this area will increase by about 12 percent from 592,000 to 667,000 ton/year. Under pre-Project conditions, the excess in gravel load corresponds to a net aggradational tendency that averages about 0.05 feet/year over the approximately 5,600-acre active channel between the confluence and the Sunshine gage. The aggradational tendency would increase modestly to about 0.055 feet/year under Maximum Load Following OS-1 conditions. (Of course, the aggradation depths will vary spatially within this area, with some locations changing significantly more than the average and some locations significantly less.) Because of the relatively small net change, however, it is our opinion that the potential impacts to this area can be adequately described based on the refined reach-wide sediment balance that will be developed from the 1-D mobile sediment-transport modeling, field observations, and knowledge of how rivers typically respond to modest changes in sediment load. As a result, additional 2-D mobile boundary modeling in this large and complex area is not warranted. 7. In spite of the above opinion that 2-D modeling of the Three Rivers Confluence is not warranted, AEA will extend the 1-D sediment-transport model downstream to at least Susitna Station (PRM 29) (Tetra Tech 2013b). Based on the limited bed material data that is available from the previous studies, the bed is primarily gravel with median (D50) size in the range of 50 to 100 millimeters (mm), and only a small amount of sand (typically <5 percent) at Sunshine. In contrast, the bed material at Susitna Station is primarily sand (D50~0.4 mm and nearly 90 percent <2 mm based on one sample). Based on this information, alone, the sediment load at Sunshine is almost certainly supply-limited with respect to sand, but is capacity-controlled with respect to sand at Susitna Station. From the above rating curve analysis, the reach between Sunshine and Susitna Station, and possibly through Susitna Station, is aggradational under pre-Project conditions with respect to both the sand and gravel loads (excess of ~250,000 and 562,000 tons/year, respectively). Under Maximum Load Following OS-1 conditions, that reach will remain aggradational for both components of the sediment load, but the magnitude of the excess in gravel supply will decrease by about one- SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 14 February 2013 third to 168,000 tons/year, while the excess in sand load will increase by about 24 percent to 694,000 tons/year, due primarily to the reduced transport capacity associated with the change in flow regime. The Yentna River supplies about 55 percent of the sand load and 35 percent of the gravel load; thus is probably a significant factor in the mainstem dynamics at and downstream from Susitna Station. Sufficient information is not available at this time to identify the location of the transition zone from supply-limited to capacity-controlled in the Lower River, and specifically whether this occurs above or below the Yentna River confluence. This determination will be important in understanding potential Project effects. The sediment-transport behavior of mainstem at the tributary mouths will also be an important factor in understanding Project effects in the Lower River, particularly in the reaches upstream from the gravel-sand transition zone. The 1-D sediment- transport modeling will be a key tool in making these assessments. 7. REFERENCES AEA (Alaska Energy Authority). 2012. Revised Study Plan: Susitna-Watana Hydroelectric Project FERC Project No. 14241. December 2012. Prepared for the Federal Energy Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska. http://www.susitna-watanahydro.org/study-plan. Cohn, T.A., and E.J. Gilroy. 1991. Estimating Loads from Periodic Records. U.S. Geological Survey Branch of Systems Analysis Technical Report 91.01. 81 p. Duan, N. 1983. Smearing Estimate: A Nonparametric Retransformation Method. Journal of the American Statistical Association, v 78(383): 605–610. Ferguson, R.I. 1986. River Loads Underestimated by Rating Curves. Water Resources Research, v 22(1): 74–76. Guy, H.P. 1964. An Analysis of Some Storm-Period Variables Affecting Stream Sediment Transport. U.S. Geological Survey Professional Paper No. 462E. Interagency Advisory Committee on Water Data (IACWD). 1982. Guidelines for determining flow frequency: Reston, Va., U.S. Geological Survey, Office of Water Data Coordination, Hydrology Subcommittee Bulletin 17B. Koch, R.W. and G.M. Smillie. 1986. Bias in Hydrologic Prediction Using Log-Transformed Regression Models. Journal of the American Water Resources Association. v 22: 717– 723. Knott, J.M., S.W. Lipscomb, and T.W. Lewis. 1987. Sediment Transport Characteristics of Selected Streams in the Susitna River Basin, Alaska: Data for Water Year 1985 and Trends in Bed-load Discharge, 1981-95. U.S. Geological Survey Open-File Report 87- 229. Prepared in cooperation with the Alaska Power Authority. Anchorage, Alaska. 45 p. MWH. 2012. Susitna-Watana Hydroelectric Project, Preliminary Susitna River Pre-Project and Post-Project Flow Stages, presented at Technical Work Group Meetings, October 23-25. Tetra Tech, Inc. 2013a. Streamflow Assessment, Susitna-Watana Hydroelectric Project (FERC No. 14241). Prepared for Alaska Energy Authority, February 5, 94 p. plus appendices. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 15 February 2013 Tetra Tech, Inc. 2013b. Reconnaissance Level Assessment of Potential Channel Change in the Lower Susitna River Segment, Susitna-Watana Hydroelectric Project (FERC No. 14241). Prepared for Alaska Energy Authority. Thomas, R.B. 1985. Estimating Total Suspended Sediment Yield with Probability Sampling. Water Resources Research. v 21(9): 1381–1388. U.S. Geological Survey. 1992. Recommendations for Use of Retransformation Methods in Regression Models Used to Estimated Sediment Loads [“The Bias Correction Problem”]. Office of Surface Water Technical Memorandum No. 93.08. December 31. U.S. Geological Survey. 2012. Streamflow Record Extension for Selected Streams in the Susitna River Basin, Alaska (Scientific Investigations Report 2012–5210). Walling, D.E. 1974. Suspended Sediment and Solute Yields from a Small Catchment Prior to Urbanization. Institute of British Geographers Special Publication No. 6: 169–192. Walling, D.E. 1977a. Limitations of the Rating Curve technique for Estimating Suspended Sediment Loads, with Particular Reference to British Rivers. In: Erosion and Solid Matter Transport in Inland Waters, Proceedings of Paris Symposium. July. IAHS Publication No. 122: 34–48. Walling, D.E. 1977b. Assessing the Accuracy of Suspended Sediment Rating Curves for a Small Basin. Water Resources Research. v 13(3): 531–538. Wolman, M.G. and J.P. Miller. 1960. Magnitude and frequency of forces in geomorphic processes. Journal of Geology. v 68(1): 54–74. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 16 February 2013 8. TABLES SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 17 February 2013 Table 3.0-1. List of streamflow gages. Gage Number Gage Name Drainage Area (sq mi) Gage Datum (NGVD 29, feet) Latitude Longitude Available Record Extended Record Main Stem River Mile 15290000 Little Susitna River near Palmer 63 917 61o 42' 37" 149o 13' 47" 1948 - 2011 - 15291000 Susitna River near Denali 950 2,440 63o 06' 14" 147o 30' 57" 1957 - 1966; 1968 - 1986 Yes 291 15291200 Maclaren River near Paxson 280 2,866 63o 07' 10" 146o 31' 45" 1958 - 1986 Yes - 15291500 Susitna River near Cantwell 4,140 1,900 62o 41' 55" 147o 32' 42" 1961 - 1972; 1980 - 1986 Yes 223 15292000 Susitna River at Gold Creek 6,160 677 62o 46' 04" 149o 41' 28" 1949 - 1996; 2001 - 2011 Yes 136 15292400 Chulitna River near Talkeetna 2,570 520 62o 33' 31" 150o 14' 02" 1958 - 1972; 1980 - 1986 Yes - 15292700 Talkeetna River near Talkeetna 1,996 400 62o 20' 49" 150o 01' 01" 1964 - 2011 Yes - 15292780 Susitna River at Sunshine 11,100 270 62o 10' 31.3" 150o 10' 13.5" 1981 - 1986 Yes 84 15292800 Montana Creek near Montana 164 250 62o 06' 19" 150o 03' 27" 2005 - 2006; 2008 - 2011 - 15294005 Willow Creek near Willow 166 350 61o 46' 51" 149o 53' 04" 1978 - 1993; 2001 - 2011 Yes - 15294010 Deception Creek near Willow 48 250 61o 44' 52" 149o 56' 14" 1978 - 1985 - 15294100 Deshka River near Willow 591 80 61o 46' 05" 150 20' 13" 1978 - 1986; 1998 - 2001 - 15294300 Skwentna River near Skwentna 2,250 200 61o 52' 23" 151 22' 01" 1959 - 1982 Yes - 15294345 Yentna River near Susitna Station 6,180 80 61o 41' 55" 150 39' 02 1980 - 1986 Yes - 15294350 Susitna River at Susitna Station 19,400 40 61o 32' 41" 150 30' 45 1974 - 1993 Yes 28 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 18 February 2013 Table 3.0-2. Sediment-transport data summary. Gage Number Gage Name Number of Samples Record Suspended Silt/Clay Suspended Sand Bed-load Sand Bed-load Gravel Pre-1985 Post-1985 Pre-1985 Post-1985 Pre-1985 Post-1985 Pre-1985 Post-1985 15292000 Susitna River at Gold Creek 45 5 46 5 45 0 38 0 1962 - 1986 15292400 Chulitna River near Talkeetna 48 2 46 2 48 0 48 0 1973 - 1986 15292700 Talkeetna River near Talkeetna 53 23 56 22 45 0 40 0 1967 - 1995 15292780 Susitna River at Sunshine 52 2 53 2 50 0 50 0 1971 - 1986 15294345 Yentna River near Susitna Station 24 1 24 1 13 0 13 0 1981 - 1986 15294350 Susitna River at Susitna Station 37 9 35 9 13 5 13 3 1975 - 2003 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 19 February 2013 Table 4.1-1. Summary of sediment load relationships used for the analysis. Gage Number Gage Name Suspended Load Bed Load Silt/Clay Sand Sand Gravel 15292000 Susitna River at Gold Creek 6.97E-10 Q3.00 1.09E-11 Q3.38 4.49E-9 Q2.46 1.89E-20 Q4.84 n = 51 (46/5), R2 = 0.89 1.02E-11 Q3.10 15292400 Chulitna River near Talkeetna 1.12E-7 Q2.66 1.01E-5 Q2.14 5.1E-6 Q2.09 2.6E-9 Q2.80 n = 50 (48/2), R2 = 0.91 n = 48 (46/2), R2 = 0.86 3.51E-12 Q3.63 1.23E-14 Q4.22 15292700 Talkeetna River near Talkeetna 2.33E-8 Q2.81 2.58E-6 Q2.32 2.17E-5 Q1.82 Parker Equation n = 76 (53/23), R2 = 0.76 n = 78 (56/22), R2 = 0.86 1.43E-12 Q3.99 15292780 Susitna River at Sunshine 2.29E-8 Q2.61 3.28E-6 Q2.12 8.16E-4 Q1.29 3.11E-17 Q4.07 n = 54 (52/2), R2 = 0.82 n = 55 (53/2), R2 = 0.83 3.68E-2 Q0.820 15294345 Yentna River near Susitna Station 1.27E-7 Q2.48 4.10E-6 Q2.14 1.93E-4 Q1.63 1.99E-9 Q2.49 n = 25 (24/1), R2 = 0.94 n = 25 (24/1), R2 = 0.84 15294350 Susitna River at Susitna Station 4.49E-8 Q2.46 3.31E-3 Q1.46 4.45E-7 Q2.04 4.85E-10 Q2.47 n = 46 (37/9), R2 = 0.87 n = 44 (35/9), R2 = 0.87 n = 18 (13/5), R2 = 0.92 n = 16 (13/3), R2 = 0.92 from Knott et al (1987) New Regression Q = Water discharge in cfs Sediment load in tons/day (tpd) n = Total number of sample points (pre-1985 data/post-1985 data) SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 20 February 2013 Table 6.0-1. Comparison of average annual sediment loads under pre-Project conditions. Gage Drainage Area (mi2) Water Discharge (acre-ft) Average Annual Load (tons) Wash Load Bed Material Total Load Silt/Clay Sand Gravel Total Watana 5,180 5,803,000 1,684,000 1,197,000 56,000 1,252,000 2,936,000 Ungaged Tributaries 980 1,242,000 117,000 213,000 11,000 223,000 340,000 Supply above Gold Creek 6,160 7,045,000 1,800,000 1,409,000 66,000 1,475,000 3,276,000 Gold Creek/Susitna nr Talkeetna 6,160 7,045,000 1,800,000 1,409,000 66,000 1,475,000 3,276,000 Talkeetna 1,996 2,938,000 940,000 866,000 57,000 923,000 1,863,000 Chulitna 2,570 6,231,000 5,264,000 3,917,000 748,000 4,665,000 9,929,000 Supply above Sunshine 10,726 16,213,000 8,005,000 6,192,000 871,000 7,063,000 15,067,000 Sunshine 11,100 17,426,000 10,012,000 6,101,000 279,000 6,380,000 16,392,000 Ungaged Tributaries 2,120 3,654,000 2,366,000 534,000 53,000 587,000 2,953,000 Yentna 6,180 14,102,000 7,162,000 8,205,000 180,000 8,385,000 15,547,000 Supply above Susitna Station 19,400 35,182,000 19,540,000 14,840,000 512,000 15,352,000 34,892,000 Susitna Station 19,400 35,182,000 19,534,000 14,278,000 260,000 14,538,000 34,072,000 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 21 February 2013 Table 6.0-2. Comparison of average annual sediment loads under Maximum Load Following OS-1 conditions. Gage Water Discharge (acre-ft) Average Annual Load (tons) Wash Load Bed Material Total Load Silt/Clay Sand Gravel Total Watana Dam 5,785,000 168,000 0 0 0 168,000 Ungaged Tribs 1,209,000 117,000 213,000 11,000 223,000 340,000 Supply above Gold Creek 6,995,000 285,000 213,000 11,000 223,000 508,000 Gold Creek 6,995,000 285,000 213,000 4,000 217,000 502,000 Talkeetna 2,938,000 940,000 866,000 57,000 923,000 1,863,000 Chulitna 6,231,000 5,264,000 3,917,000 748,000 4,665,000 9,929,000 Supply above Sunshine 16,164,000 6,490,000 4,995,000 809,000 5,804,000 12,294,000 Sunshine 17,375,000 8,497,000 4,995,000 142,000 5,137,000 13,634,000 Ungaged Tributaries 3,654,000 2,366,000 534,000 53,000 587,000 2,953,000 Yentna 14,102,000 7,162,000 8,205,000 180,000 8,385,000 15,547,000 Supply above Susitna Station 35,131,000 18,025,000 13,734,000 375,000 14,109,000 32,134,000 Susitna Station 35,131,000 18,019,000 13,040,000 207,000 13,247,000 31,266,000 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 22 February 2013 9. FIGURES SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 23 February 2013 Figure 3.0-1. Susitna River study area and large-scale river segments. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 24 February 2013 Figure 5.1-1. Estimated annual silt/clay, sand and gravel loads at the Gold Creek (Gage No. 15292000)/, Susitna River near Talkeetna (Gage No. 15292100) gage over the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 25 February 2013 Figure 5.1-2. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Sunshine (Gage No. 15292780) gage over the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 26 February 2013 Figure 5.1-3. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Susitna Station (Gage No. 15294350) gage over the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 27 February 2013 Figure 5.1-4. Estimated annual silt/clay, sand and gravel loads at the Chulitna River near Talkeetna (Gage No. 15292400), Chulitna River below Canyon near Talkeetna (Gage No. 15292410) gage over the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 28 February 2013 Figure 5.1-5. Estimated annual silt/clay, sand and gravel loads at the Talkeetna River near Talkeetna (Gage No. 15292700) gage over the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 29 February 2013 Figure 5.1-6. Estimated annual silt/clay, sand and gravel loads at the Yentna River near Susitna Station (Gage No. 15294345) gage over the 61-year period of flows under pre-Project conditions. Also shown is the annual flow volume for each of the years. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 30 February 2013 Figure 5.1.7. Average annual silt/clay, sand and gravel loads under pre-Project conditions for the three mainstem gages and three major tributary gages considered in the analysis. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 31 February 2013 Figure 5.2-1. Estimated annual silt/clay, sand and gravel loads at the Gold Creek (Gage No. 15292000), Susitna River near Talkeetna (Gage No. 15292100) gage over the 61-year period of flows under Max LF OS-1conditions. Also shown is the annual flow volume for each of the years. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 32 February 2013 Figure 5.2-2. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Sunshine (Gage No. 15292780) gage over the 61-year period of flows under Max LF OS-1conditions. Also shown is the annual flow volume for each of the years. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 33 February 2013 Figure 5.2-3. Estimated annual silt/clay, sand and gravel loads at the Susitna River at Susitna Station (Gage No. 15294350) gage over the 61-year period of flows under Max LF OS-1conditions. Also shown is the annual flow volume for each of the years. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 34 February 2013 Figure 5.2.4. Average annual silt/clay, sand and gravel loads under Maximum Load Following OS-1 conditions for the three mainstem gages and three major tributary gages considered in the analysis. Note that the tributary loads are the same as pre-Project conditions. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 35 February 2013 1.80 5.26 0.94 10.00 7.16 19.50 0.29 8.50 18.02 - 5 10 15 20 25 Gold Creek Chulitna Talkeetna Sunshine Yentna Susitna StationAverage Annual Sediment Load (tons)MillionsPre-Project Maximum Load Following OS-1 Figure 6.0-1. Average annual silt/clay loads at the three mainstem gages and the three primary tributary gages under pre-Project and Maximum Load Following OS-1 conditions. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 36 February 2013 1.41 3.92 0.87 6.10 8.21 14.23 0.21 5.00 13.04 - 2 4 6 8 10 12 14 16 Gold Creek Chulitna Talkeetna Sunshine Yentna Susitna StationAverage Annual Sediment Load (tons)MillionsPre-Project Maximum Load Following OS-1 Figure 6.0-2. Average annual sand loads at the three mainstem gages and the three primary tributary gages under pre-Project and Maximum Load Following OS-1 conditions. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 37 February 2013 Figure 6.0-3. Average annual gravel loads at the three mainstem gages and the three primary tributary gages under pre-Project and Maximum Load Following OS-1 conditions. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 38 February 2013 1.2 0.2 1.4 1.4 0.9 3.9 6.2 6.1 0.5 8.2 14.8 14.3 0.0 0.2 0.2 5.0 5.0 13.7 13.0 0 2 4 6 8 10 12 14 16 Annual Load (tons)MillionsPre-project Maximum Load Following OS-1 Figure 6.0-4. Average annual sand loads at the mainstem and tributary gages, along with the estimated annual sand load from ungaged tributaries, under pre-Project and Maximum Load Following OS-1 conditions. Also shown is the accumulated sediment supply to key points along the reach based on the gaged and ungaged sand loads. SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 39 February 2013 56 11 66 66 57 748 871 279 53 180 512 260 0 11 4 809 142 375 207 0 100 200 300 400 500 600 700 800 900 1,000 Annual Load (tons)ThousandsPre-project Maximum Load Following OS-1 Figure 6.0-5. Average annual gravel loads at the mainstem and tributary gages, along with the estimated annual gravel load from ungaged tributaries, under pre- Project and Maximum Load Following OS-1 conditions. Also shown is the accumulated sediment supply to key points along the reach based on the gaged and ungaged gravel loads. APPENDIX A. SEDIMENT TRANSPORT DATA AND REGRESSION SUMMARY Susitna-Watana Hydroelectric Project (FERC No. 14241) Development of Sediment Transport Relationships and an Initial Sediment Balance for the Middle and Lower Susitna River Segments Prepared for Alaska Energy Authority Prepared by Tetra Tech February 2013 APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.1 February 2013 Figure A.1 – Suspended silt/clay sediment transport data and rating equations for Susitna River at Gold Creek and Susitna River near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.2 February 2013 Figure A.2 – Suspended sand sediment transport data and rating equations for Susitna River at Gold Creek and Susitna River near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.3 February 2013 Figure A.3 – Bed-load Sand sediment transport data and rating equations for Susitna River at Gold Creek and Susitna River near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.4 February 2013 Figure A.4 – Bed-load gravel sediment transport data and rating equations for Susitna River at Gold Creek and Susitna River near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.5 February 2013 Figure A.5 – Suspended silt/clay sediment transport data and rating equations for Chulitna River near Talkeetna and Chulitna River below Canyon near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.6 February 2013 Figure A.6 – Suspended sand sediment transport data and rating equations for Chulitna River near Talkeetna and Chulitna River below Canyon near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.7 February 2013 Figure A.7 – Bed-load sand sediment transport data and rating equations for Chulitna River near Talkeetna and Chulitna River below Canyon near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.8 February 2013 Figure A.8 – Bed-load Gravel sediment transport data and rating equations for Chulitna River near Talkeetna and Chulitna River below Canyon near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.9 February 2013 Figure A.9 – Suspended silt/clay sediment transport data and rating equations for Talkeetna River near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.10 February 2013 Figure A.10 – Suspended sand sediment transport data and rating equations for Talkeetna River near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.11 February 2013 Figure A.11 – Bed-load sand sediment transport data and rating equations for Talkeetna River near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.12 February 2013 Figure A.12 – Bed-load gravel sediment transport data and rating equations for Talkeetna River near Talkeetna APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.13 February 2013 Figure A.13 – Suspended silt/clay sediment transport data and rating equations for Susitna River at Sunshine APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.14 February 2013 Figure A.14 – Suspended sand sediment transport data and rating equations for Susitna River at Sunshine APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.15 February 2013 Figure A.15 – Bed-load sand sediment transport data and rating equations for Susitna River at Sunshine APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.16 February 2013 Figure A.16 – Bed-load gravel sediment transport data and rating equations for Susitna River at Sunshine APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.17 February 2013 Figure A.17 – Suspended silt/clay sediment transport data and rating equations for Yentna River near Susitna Station APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.18 February 2013 Figure A.18 – Suspended sand sediment transport data and rating equations for Yentna River near Susitna Station APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.19 February 2013 Figure A.19 – Bed-load sand sediment transport data and rating equations for Yentna River near Susitna Station APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.20 February 2013 Figure A.20 – Bed-load gravel sediment transport data and rating equations for Yentna River near Susitna Station APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.21 February 2013 Figure A.21 – Suspended silt/clay sediment transport data and rating equations for Susitna River near Susitna Station APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.22 February 2013 Figure A.22 – Suspended sand sediment transport data and rating equations for Susitna River near Susitna Station APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.23 February 2013 Figure A.23 – Bed-load sand sediment transport data and rating equations for Susitna River near Susitna Station APPENDIX A S EDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page A.24 February 2013 Figure A.24 – Bed-load gravel sediment transport data and rating equations for Susitna River near Susitna Station APPENDIX B.1. ANNUAL SEDIMENT LOAD TABULAR SUMMARY FOR PRE-PROJECT CONDITIONS Susitna-Watana Hydroelectric Project (FERC No. 14241) Development of Sediment Transport Relationships and an Initial Sediment Balance for the Middle and Lower Susitna River Segments Prepared for Alaska Energy Authority Prepared by Tetra Tech February 2013 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.1 February 2013 Table B.1-1 – Annual Sediment Load for Pre-Project Conditions for Susitna River at Gold Creek Susitna River at Gold Creek - 15292000 WY Water Volume (acre-ft)Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1950 5,810,000 914,000 598,000 1,512,000 38,900 7,520 46,420 1,558,420 1951 6,590,000 1,260,000 845,000 2,105,000 52,900 11,900 64,800 2,169,800 1952 6,920,000 2,070,000 1,550,000 3,620,000 74,200 48,900 123,100 3,743,100 1953 7,310,000 1,450,000 985,000 2,435,000 59,100 17,200 76,300 2,511,300 1954 7,010,000 1,480,000 1,020,000 2,500,000 60,200 19,300 79,500 2,579,500 1955 7,430,000 2,350,000 1,810,000 4,160,000 81,800 79,600 161,400 4,321,400 1956 8,310,000 2,930,000 2,230,000 5,160,000 103,000 81,800 184,800 5,344,800 1957 7,520,000 1,850,000 1,310,000 3,160,000 71,600 30,300 101,900 3,261,900 1958 6,860,000 1,470,000 1,050,000 2,520,000 56,600 29,100 85,700 2,605,700 1959 7,650,000 2,590,000 2,010,000 4,600,000 89,500 103,000 192,500 4,792,500 1960 7,030,000 1,440,000 999,000 2,439,000 56,900 21,600 78,500 2,517,500 1961 7,830,000 1,920,000 1,410,000 3,330,000 71,700 52,100 123,800 3,453,800 1962 8,370,000 3,960,000 3,440,000 7,400,000 118,000 423,000 541,000 7,941,000 1963 8,020,000 2,700,000 2,050,000 4,750,000 95,000 73,100 168,100 4,918,100 1964 7,100,000 5,030,000 4,800,000 9,830,000 127,000 872,000 999,000 10,829,000 1965 7,360,000 1,930,000 1,390,000 3,320,000 73,800 31,900 105,700 3,425,700 1966 6,830,000 1,940,000 1,500,000 3,440,000 67,100 85,400 152,500 3,592,500 1967 8,120,000 3,440,000 2,840,000 6,280,000 110,000 260,000 370,000 6,650,000 1968 7,110,000 1,950,000 1,430,000 3,380,000 71,500 39,100 110,600 3,490,600 1969 4,050,000 337,000 198,000 535,000 15,000 1,150 16,150 551,150 1970 5,500,000 896,000 587,000 1,483,000 37,900 7,230 45,130 1,528,130 1971 7,420,000 3,670,000 3,220,000 6,890,000 107,000 390,000 497,000 7,387,000 1972 7,880,000 2,860,000 2,370,000 5,230,000 91,300 219,000 310,300 5,540,300 1973 5,850,000 1,270,000 919,000 2,189,000 47,400 31,400 78,800 2,267,800 1974 5,520,000 858,000 565,000 1,423,000 35,700 8,170 43,870 1,466,870 1975 7,440,000 2,050,000 1,490,000 3,540,000 76,700 37,500 114,200 3,654,200 1976 5,930,000 967,000 642,000 1,609,000 40,200 9,120 49,320 1,658,320 1977 7,320,000 2,330,000 1,810,000 4,140,000 80,100 83,400 163,500 4,303,500 1978 5,930,000 687,000 425,000 1,112,000 30,900 3,240 34,140 1,146,140 1979 6,870,000 1,630,000 1,160,000 2,790,000 63,000 24,600 87,600 2,877,600 Susitna River at Gold Creek – 15292000 cont. APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.2 February 2013 WY Water Volume (acre-ft)Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1980 7,780,000 2,240,000 1,680,000 3,920,000 79,900 57,600 137,500 4,057,500 1981 8,660,000 3,610,000 2,960,000 6,570,000 113,000 188,000 301,000 6,871,000 1982 7,000,000 1,340,000 913,000 2,253,000 54,300 14,800 69,100 2,322,100 1983 7,180,000 1,370,000 924,000 2,294,000 56,200 14,200 70,400 2,364,400 1984 6,950,000 1,470,000 1,050,000 2,520,000 56,900 29,100 86,000 2,606,000 1985 7,150,000 1,720,000 1,230,000 2,950,000 65,800 29,300 95,100 3,045,100 1986 6,180,000 846,000 535,000 1,381,000 37,200 4,920 42,120 1,423,120 1987 7,640,000 1,770,000 1,260,000 3,030,000 68,000 29,300 97,300 3,127,300 1988 7,420,000 1,750,000 1,230,000 2,980,000 68,900 24,200 93,100 3,073,100 1989 7,420,000 1,450,000 986,000 2,436,000 59,300 15,900 75,200 2,511,200 1990 9,420,000 3,180,000 2,400,000 5,580,000 113,000 80,800 193,800 5,773,800 1991 6,180,000 1,040,000 694,000 1,734,000 43,100 10,100 53,200 1,787,200 1992 6,330,000 1,170,000 791,000 1,961,000 48,600 11,200 59,800 2,020,800 1993 7,310,000 1,470,000 998,000 2,468,000 60,200 15,800 76,000 2,544,000 1994 7,210,000 1,550,000 1,110,000 2,660,000 58,500 32,500 91,000 2,751,000 1995 7,450,000 1,570,000 1,080,000 2,650,000 63,000 18,900 81,900 2,731,900 1996 4,940,000 451,000 266,000 717,000 20,200 1,510 21,710 738,710 1997 6,370,000 1,210,000 815,000 2,025,000 50,100 11,700 61,800 2,086,800 1998 6,790,000 1,480,000 1,020,000 2,500,000 60,100 17,000 77,100 2,577,100 1999 6,730,000 1,380,000 962,000 2,342,000 54,500 20,200 74,700 2,416,700 2000 7,430,000 1,920,000 1,390,000 3,310,000 71,100 34,600 105,700 3,415,700 2001 6,910,000 1,590,000 1,130,000 2,720,000 60,800 25,700 86,500 2,806,500 2002 6,140,000 1,040,000 693,000 1,733,000 42,700 10,900 53,600 1,786,600 2003 7,440,000 1,700,000 1,230,000 2,930,000 64,500 35,500 100,000 3,030,000 2004 6,820,000 1,320,000 900,000 2,220,000 54,000 15,600 69,600 2,289,600 2005 8,840,000 2,890,000 2,130,000 5,020,000 107,000 56,400 163,400 5,183,400 2006 7,470,000 2,270,000 1,730,000 4,000,000 80,300 79,000 159,300 4,159,300 2007 6,990,000 1,040,000 662,000 1,702,000 45,300 6,460 51,760 1,753,760 2008 6,460,000 1,010,000 662,000 1,672,000 42,600 8,510 51,110 1,723,110 2009 6,880,000 1,270,000 856,000 2,126,000 51,900 14,600 66,500 2,192,500 2010 7,340,000 1,480,000 1,000,000 2,480,000 60,600 16,600 77,200 2,557,200 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.3 February 2013 Table B.1-2. Annual Sediment Load for Pre-Project Conditions for Chulitna River near Talkeetna Chulitna River near Talkeetna - 15292400 WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1950 5,370,000 3,440,000 1,940,000 5,380,000 885,000 476,000 1,361,000 6,741,000 1951 6,130,000 4,550,000 2,500,000 7,050,000 1,150,000 634,000 1,784,000 8,834,000 1952 5,940,000 5,190,000 2,670,000 7,860,000 1,210,000 736,000 1,946,000 9,806,000 1953 6,690,000 4,910,000 2,700,000 7,610,000 1,240,000 684,000 1,924,000 9,534,000 1954 6,440,000 5,090,000 2,730,000 7,820,000 1,250,000 713,000 1,963,000 9,783,000 1955 6,320,000 5,510,000 2,830,000 8,340,000 1,290,000 781,000 2,071,000 10,411,000 1956 7,110,000 6,980,000 3,520,000 10,500,000 1,600,000 993,000 2,593,000 13,093,000 1957 6,690,000 5,580,000 2,940,000 8,520,000 1,340,000 785,000 2,125,000 10,645,000 1958 6,350,000 5,080,000 2,650,000 7,730,000 1,190,000 719,000 1,909,000 9,639,000 1959 6,060,000 5,540,000 2,780,000 8,320,000 1,260,000 791,000 2,051,000 10,371,000 1960 6,070,000 4,620,000 2,460,000 7,080,000 1,110,000 649,000 1,759,000 8,839,000 1961 6,840,000 6,530,000 3,240,000 9,770,000 1,470,000 935,000 2,405,000 12,175,000 1962 6,380,000 5,850,000 2,930,000 8,780,000 1,320,000 836,000 2,156,000 10,936,000 1963 5,990,000 5,220,000 2,650,000 7,870,000 1,210,000 743,000 1,953,000 9,823,000 1964 6,760,000 9,370,000 4,080,000 13,450,000 1,820,000 1,390,000 3,210,000 16,660,000 1965 6,780,000 6,140,000 3,100,000 9,240,000 1,410,000 876,000 2,286,000 11,526,000 1966 6,260,000 5,960,000 2,960,000 8,920,000 1,340,000 853,000 2,193,000 11,113,000 1967 8,050,000 14,300,000 5,670,000 19,970,000 2,510,000 2,170,000 4,680,000 24,650,000 1968 6,660,000 7,610,000 3,570,000 11,180,000 1,610,000 1,100,000 2,710,000 13,890,000 1969 4,420,000 2,610,000 1,470,000 4,080,000 652,000 361,000 1,013,000 5,093,000 1970 6,320,000 5,660,000 2,860,000 8,520,000 1,300,000 806,000 2,106,000 10,626,000 1971 6,090,000 6,670,000 3,110,000 9,780,000 1,390,000 971,000 2,361,000 12,141,000 1972 6,050,000 4,800,000 2,520,000 7,320,000 1,140,000 677,000 1,817,000 9,137,000 1973 5,490,000 3,780,000 2,060,000 5,840,000 930,000 528,000 1,458,000 7,298,000 1974 5,730,000 3,780,000 2,120,000 5,900,000 971,000 524,000 1,495,000 7,395,000 1975 6,490,000 5,550,000 2,880,000 8,430,000 1,310,000 785,000 2,095,000 10,525,000 1976 5,510,000 3,820,000 2,090,000 5,910,000 942,000 533,000 1,475,000 7,385,000 1977 6,330,000 5,510,000 2,830,000 8,340,000 1,290,000 781,000 2,071,000 10,411,000 1978 5,540,000 3,490,000 1,960,000 5,450,000 885,000 483,000 1,368,000 6,818,000 1979 6,470,000 5,470,000 2,840,000 8,310,000 1,290,000 773,000 2,063,000 10,373,000 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.4 February 2013 Chulitna River near Talkeetna – 15292400 cont. WY Water Volume (acre-ft)Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1980 7,010,000 7,730,000 3,570,000 11,300,000 1,590,000 1,130,000 2,720,000 14,020,000 1981 7,540,000 9,890,000 4,340,000 14,230,000 1,930,000 1,460,000 3,390,000 17,620,000 1982 6,120,000 5,280,000 2,690,000 7,970,000 1,220,000 751,000 1,971,000 9,941,000 1983 5,950,000 4,530,000 2,380,000 6,910,000 1,080,000 639,000 1,719,000 8,629,000 1984 6,140,000 4,300,000 2,330,000 6,630,000 1,060,000 602,000 1,662,000 8,292,000 1985 6,120,000 5,080,000 2,620,000 7,700,000 1,190,000 720,000 1,910,000 9,610,000 1986 5,410,000 3,510,000 1,960,000 5,470,000 897,000 488,000 1,385,000 6,855,000 1987 7,140,000 6,240,000 3,130,000 9,370,000 1,420,000 894,000 2,314,000 11,684,000 1988 5,860,000 3,880,000 2,170,000 6,050,000 994,000 537,000 1,531,000 7,581,000 1989 6,480,000 5,330,000 2,800,000 8,130,000 1,280,000 750,000 2,030,000 10,160,000 1990 7,920,000 7,250,000 3,660,000 10,910,000 1,650,000 1,030,000 2,680,000 13,590,000 1991 5,750,000 4,300,000 2,300,000 6,600,000 1,040,000 605,000 1,645,000 8,245,000 1992 5,450,000 4,180,000 2,230,000 6,410,000 1,010,000 587,000 1,597,000 8,007,000 1993 7,250,000 6,750,000 3,430,000 10,180,000 1,560,000 959,000 2,519,000 12,699,000 1994 6,640,000 5,020,000 2,690,000 7,710,000 1,220,000 705,000 1,925,000 9,635,000 1995 6,290,000 4,620,000 2,520,000 7,140,000 1,160,000 645,000 1,805,000 8,945,000 1996 4,930,000 2,390,000 1,460,000 3,850,000 658,000 324,000 982,000 4,832,000 1997 5,550,000 3,940,000 2,150,000 6,090,000 977,000 551,000 1,528,000 7,618,000 1998 5,960,000 4,770,000 2,530,000 7,300,000 1,150,000 670,000 1,820,000 9,120,000 1999 5,850,000 4,360,000 2,320,000 6,680,000 1,050,000 613,000 1,663,000 8,343,000 2000 6,460,000 5,830,000 2,920,000 8,750,000 1,320,000 832,000 2,152,000 10,902,000 2001 5,680,000 3,930,000 2,150,000 6,080,000 972,000 549,000 1,521,000 7,601,000 2002 5,860,000 4,230,000 2,310,000 6,540,000 1,060,000 591,000 1,651,000 8,191,000 2003 6,580,000 4,640,000 2,540,000 7,180,000 1,150,000 648,000 1,798,000 8,978,000 2004 5,730,000 3,370,000 1,960,000 5,330,000 892,000 461,000 1,353,000 6,683,000 2005 8,470,000 9,190,000 4,480,000 13,670,000 2,030,000 1,320,000 3,350,000 17,020,000 2006 6,000,000 4,890,000 2,510,000 7,400,000 1,130,000 695,000 1,825,000 9,225,000 2007 5,670,000 3,180,000 1,880,000 5,060,000 861,000 434,000 1,295,000 6,355,000 2008 5,410,000 3,130,000 1,820,000 4,950,000 833,000 429,000 1,262,000 6,212,000 2009 5,600,000 3,140,000 1,850,000 4,990,000 848,000 429,000 1,277,000 6,267,000 2010 5,920,000 3,620,000 2,070,000 5,690,000 940,000 499,000 1,439,000 7,129,000 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.5 February 2013 Table B.1-3. Annual Sediment Load for Pre-Project Conditions for Talkeetna River near Talkeetna Talkeetna River near Talkeetna - 15292700 WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1950 2,460,000 459,000 454,000 913,000 65,900 17,300 83,200 996,200 1951 2,800,000 631,000 601,000 1,232,000 84,000 26,800 110,800 1,342,800 1952 2,930,000 1,010,000 836,000 1,846,000 102,000 67,100 169,100 2,015,100 1953 3,080,000 720,000 676,000 1,396,000 93,400 33,100 126,500 1,522,500 1954 2,960,000 736,000 679,000 1,415,000 92,100 35,400 127,500 1,542,500 1955 3,130,000 1,140,000 923,000 2,063,000 111,000 77,300 188,300 2,251,300 1956 3,540,000 1,420,000 1,150,000 2,570,000 137,000 97,900 234,900 2,804,900 1957 3,160,000 908,000 801,000 1,709,000 104,000 51,100 155,100 1,864,100 1958 2,870,000 642,000 600,000 1,242,000 82,900 30,900 113,800 1,355,800 1959 2,950,000 826,000 735,000 1,561,000 95,900 45,600 141,500 1,702,500 1960 2,840,000 607,000 581,000 1,188,000 81,600 26,000 107,600 1,295,600 1961 3,150,000 789,000 724,000 1,513,000 97,300 40,000 137,300 1,650,300 1962 3,160,000 1,020,000 860,000 1,880,000 107,000 62,800 169,800 2,049,800 1963 3,000,000 867,000 764,000 1,631,000 98,700 49,200 147,900 1,778,900 1964 2,870,000 1,210,000 925,000 2,135,000 106,000 88,300 194,300 2,329,300 1965 3,440,000 1,300,000 1,050,000 2,350,000 126,000 89,700 215,700 2,565,700 1966 3,060,000 1,110,000 886,000 1,996,000 106,000 76,500 182,500 2,178,500 1967 3,240,000 1,640,000 1,160,000 2,800,000 126,000 114,000 240,000 3,040,000 1968 3,240,000 1,160,000 942,000 2,102,000 113,000 79,700 192,700 2,294,700 1969 1,630,000 161,000 183,000 344,000 30,600 3,070 33,670 377,670 1970 2,530,000 574,000 535,000 1,109,000 73,500 27,700 101,200 1,210,200 1971 3,840,000 4,070,000 2,300,000 6,370,000 196,000 285,000 481,000 6,851,000 1972 3,250,000 1,130,000 936,000 2,066,000 114,000 72,900 186,900 2,252,900 1973 2,790,000 842,000 691,000 1,533,000 86,100 53,900 140,000 1,673,000 1974 2,410,000 445,000 435,000 880,000 62,800 17,700 80,500 960,500 1975 3,140,000 1,030,000 876,000 1,906,000 109,000 64,500 173,500 2,079,500 1976 2,470,000 527,000 493,000 1,020,000 68,700 25,500 94,200 1,114,200 1977 3,150,000 1,420,000 1,060,000 2,480,000 118,000 105,000 223,000 2,703,000 1978 2,390,000 424,000 418,000 842,000 60,900 17,400 78,300 920,300 1979 3,220,000 1,360,000 1,050,000 2,410,000 119,000 100,000 219,000 2,629,000 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.6 February 2013 Talkeetna River near Talkeetna – 15292700 cont. WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1980 3,150,000 1,020,000 840,000 1,860,000 104,000 66,600 170,600 2,030,600 1981 3,200,000 1,840,000 1,250,000 3,090,000 128,000 139,000 267,000 3,357,000 1982 3,040,000 1,130,000 897,000 2,027,000 107,000 77,000 184,000 2,211,000 1983 2,630,000 477,000 473,000 950,000 68,800 18,200 87,000 1,037,000 1984 2,640,000 610,000 551,000 1,161,000 74,800 30,900 105,700 1,266,700 1985 3,080,000 1,060,000 875,000 1,935,000 107,000 67,800 174,800 2,109,800 1986 2,430,000 425,000 426,000 851,000 62,800 15,200 78,000 929,000 1987 3,480,000 2,070,000 1,270,000 3,340,000 129,000 115,000 244,000 3,584,000 1988 2,710,000 546,000 530,000 1,076,000 75,000 21,900 96,900 1,172,900 1989 3,070,000 882,000 775,000 1,657,000 100,000 50,100 150,100 1,807,100 1990 3,900,000 1,570,000 1,230,000 2,800,000 143,000 111,000 254,000 3,054,000 1991 2,740,000 727,000 646,000 1,373,000 84,900 42,000 126,900 1,499,900 1992 2,560,000 653,000 591,000 1,244,000 78,500 34,700 113,200 1,357,200 1993 3,500,000 1,260,000 1,040,000 2,300,000 126,000 82,100 208,100 2,508,100 1994 3,140,000 869,000 758,000 1,627,000 98,500 50,200 148,700 1,775,700 1995 2,920,000 701,000 650,000 1,351,000 88,600 33,500 122,100 1,473,100 1996 2,260,000 317,000 338,000 655,000 53,100 8,410 61,510 716,510 1997 2,590,000 601,000 557,000 1,158,000 75,900 29,600 105,500 1,263,500 1998 2,790,000 776,000 687,000 1,463,000 89,600 42,800 132,400 1,595,400 1999 2,790,000 805,000 683,000 1,488,000 87,100 48,900 136,000 1,624,000 2000 3,230,000 1,260,000 1,000,000 2,260,000 117,000 92,700 209,700 2,469,700 2001 2,680,000 621,000 571,000 1,192,000 77,500 32,200 109,700 1,301,700 2002 2,750,000 700,000 630,000 1,330,000 84,100 37,000 121,100 1,451,100 2003 3,080,000 762,000 686,000 1,448,000 92,600 40,400 133,000 1,581,000 2004 2,620,000 438,000 450,000 888,000 67,700 12,700 80,400 968,400 2005 4,240,000 1,970,000 1,530,000 3,500,000 174,000 146,000 320,000 3,820,000 2006 2,910,000 1,290,000 906,000 2,196,000 101,000 81,300 182,300 2,378,300 2007 2,600,000 436,000 447,000 883,000 67,500 14,100 81,600 964,600 2008 2,490,000 433,000 437,000 870,000 65,000 15,000 80,000 950,000 2009 2,580,000 430,000 440,000 870,000 66,200 13,600 79,800 949,800 2010 2,730,000 497,000 495,000 992,000 72,600 18,100 90,700 1,082,700 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.7 February 2013 Table B.1-4. Annual Sediment Load for Pre-Project Conditions for Susitna River at Sunshine Susitna River at Sunshine - 15292780 WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1950 14,200,000 6,000,000 3,920,000 9,920,000 148,000 130,000 278,000 10,198,000 1951 16,200,000 8,080,000 5,100,000 13,180,000 176,000 172,000 348,000 13,528,000 1952 16,700,000 11,000,000 6,260,000 17,260,000 187,000 324,000 511,000 17,771,000 1953 17,900,000 8,980,000 5,630,000 14,610,000 195,000 202,000 397,000 15,007,000 1954 17,200,000 9,160,000 5,640,000 14,800,000 189,000 212,000 401,000 15,201,000 1955 17,800,000 12,000,000 6,730,000 18,730,000 200,000 369,000 569,000 19,299,000 1956 20,000,000 15,200,000 8,440,000 23,640,000 235,000 454,000 689,000 24,329,000 1957 18,300,000 10,700,000 6,370,000 17,070,000 203,000 271,000 474,000 17,544,000 1958 16,600,000 8,520,000 5,170,000 13,690,000 178,000 228,000 406,000 14,096,000 1959 18,400,000 13,100,000 7,290,000 20,390,000 211,000 406,000 617,000 21,007,000 1960 17,100,000 8,590,000 5,320,000 13,910,000 184,000 208,000 392,000 14,302,000 1961 19,000,000 10,800,000 6,410,000 17,210,000 209,000 297,000 506,000 17,716,000 1962 19,900,000 16,500,000 8,610,000 25,110,000 232,000 664,000 896,000 26,006,000 1963 19,300,000 14,100,000 7,810,000 21,910,000 223,000 424,000 647,000 22,557,000 1964 16,400,000 14,700,000 7,380,000 22,080,000 190,000 663,000 853,000 22,933,000 1965 18,700,000 11,700,000 6,830,000 18,530,000 210,000 305,000 515,000 19,045,000 1966 17,100,000 10,100,000 5,860,000 15,960,000 188,000 297,000 485,000 16,445,000 1967 19,400,000 14,900,000 8,100,000 23,000,000 226,000 497,000 723,000 23,723,000 1968 17,800,000 11,100,000 6,390,000 17,490,000 197,000 314,000 511,000 18,001,000 1969 10,100,000 2,590,000 1,940,000 4,530,000 94,700 61,900 156,600 4,686,600 1970 14,300,000 6,420,000 4,140,000 10,560,000 151,000 139,000 290,000 10,850,000 1971 18,400,000 15,600,000 8,030,000 23,630,000 213,000 649,000 862,000 24,492,000 1972 19,200,000 12,400,000 7,010,000 19,410,000 214,000 391,000 605,000 20,015,000 1973 15,100,000 7,590,000 4,620,000 12,210,000 160,000 206,000 366,000 12,576,000 1974 14,100,000 5,890,000 3,870,000 9,760,000 147,000 127,000 274,000 10,034,000 1975 18,400,000 11,700,000 6,780,000 18,480,000 207,000 307,000 514,000 18,994,000 1976 14,900,000 6,550,000 4,210,000 10,760,000 156,000 151,000 307,000 11,067,000 1977 17,900,000 11,800,000 6,660,000 18,460,000 200,000 366,000 566,000 19,026,000 1978 14,800,000 5,240,000 3,590,000 8,830,000 149,000 115,000 264,000 9,094,000 1979 17,400,000 10,300,000 6,050,000 16,350,000 192,000 277,000 469,000 16,819,000 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.8 February 2013 Susitna River at Sunshine – 15292780 cont. WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1980 18,900,000 11,600,000 6,700,000 18,300,000 210,000 334,000 544,000 18,844,000 1981 20,500,000 16,800,000 8,780,000 25,580,000 237,000 674,000 911,000 26,491,000 1982 17,400,000 9,220,000 5,620,000 14,840,000 189,000 231,000 420,000 15,260,000 1983 17,100,000 8,300,000 5,170,000 13,470,000 182,000 201,000 383,000 13,853,000 1984 17,100,000 8,460,000 5,190,000 13,650,000 181,000 219,000 400,000 14,050,000 1985 17,600,000 10,400,000 6,090,000 16,490,000 194,000 277,000 471,000 16,961,000 1986 14,900,000 5,710,000 3,860,000 9,570,000 153,000 117,000 270,000 9,840,000 1987 19,400,000 10,900,000 6,520,000 17,420,000 213,000 286,000 499,000 17,919,000 1988 18,000,000 9,940,000 6,030,000 15,970,000 198,000 236,000 434,000 16,404,000 1989 18,500,000 9,600,000 5,920,000 15,520,000 201,000 223,000 424,000 15,944,000 1990 23,000,000 16,200,000 9,140,000 25,340,000 265,000 469,000 734,000 26,074,000 1991 15,600,000 7,180,000 4,540,000 11,720,000 165,000 168,000 333,000 12,053,000 1992 15,700,000 7,870,000 4,850,000 12,720,000 167,000 186,000 353,000 13,073,000 1993 18,800,000 10,400,000 6,310,000 16,710,000 208,000 244,000 452,000 17,162,000 1994 18,200,000 9,290,000 5,670,000 14,960,000 195,000 242,000 437,000 15,397,000 1995 18,400,000 9,740,000 5,980,000 15,720,000 201,000 226,000 427,000 16,147,000 1996 12,800,000 3,780,000 2,760,000 6,540,000 126,000 79,800 205,800 6,745,800 1997 16,800,000 8,860,000 5,400,000 14,260,000 182,000 215,000 397,000 14,657,000 1998 17,800,000 10,500,000 6,250,000 16,750,000 198,000 260,000 458,000 17,208,000 1999 17,600,000 9,660,000 5,790,000 15,450,000 192,000 255,000 447,000 15,897,000 2000 19,300,000 12,400,000 7,090,000 19,490,000 216,000 366,000 582,000 20,072,000 2001 17,200,000 9,100,000 5,500,000 14,600,000 186,000 236,000 422,000 15,022,000 2002 15,700,000 7,210,000 4,600,000 11,810,000 166,000 161,000 327,000 12,137,000 2003 18,600,000 9,850,000 5,960,000 15,810,000 201,000 258,000 459,000 16,269,000 2004 16,900,000 8,110,000 5,130,000 13,240,000 181,000 179,000 360,000 13,600,000 2005 22,400,000 16,700,000 9,350,000 26,050,000 263,000 459,000 722,000 26,772,000 2006 18,100,000 11,400,000 6,550,000 17,950,000 202,000 339,000 541,000 18,491,000 2007 17,200,000 6,950,000 4,650,000 11,600,000 180,000 140,000 320,000 11,920,000 2008 16,000,000 6,770,000 4,420,000 11,190,000 167,000 147,000 314,000 11,504,000 2009 16,900,000 7,720,000 4,970,000 12,690,000 181,000 165,000 346,000 13,036,000 2010 18,000,000 8,790,000 5,540,000 14,330,000 194,000 194,000 388,000 14,718,000 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.9 February 2013 Table B.1-5. Annual Sediment Load for Pre-Project Conditions for Yentna River near Susitna Station Yentna River near Susitna Station - 15294345 WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1950 11,800,000 4,730,000 4,820,000 9,550,000 1,050,000 122,000 1,172,000 10,722,000 1951 13,400,000 6,180,000 6,160,000 12,340,000 1,290,000 155,000 1,445,000 13,785,000 1952 13,300,000 7,180,000 6,810,000 13,990,000 1,330,000 180,000 1,510,000 15,500,000 1953 14,800,000 6,750,000 6,730,000 13,480,000 1,410,000 168,000 1,578,000 15,058,000 1954 14,200,000 6,830,000 6,720,000 13,550,000 1,380,000 171,000 1,551,000 15,101,000 1955 14,300,000 7,710,000 7,290,000 15,000,000 1,420,000 194,000 1,614,000 16,614,000 1956 15,800,000 9,650,000 9,000,000 18,650,000 1,700,000 236,000 1,936,000 20,586,000 1957 14,900,000 7,610,000 7,370,000 14,980,000 1,480,000 191,000 1,671,000 16,651,000 1958 13,700,000 6,140,000 6,030,000 12,170,000 1,260,000 158,000 1,418,000 13,588,000 1959 14,800,000 8,460,000 7,950,000 16,410,000 1,530,000 210,000 1,740,000 18,150,000 1960 13,000,000 5,490,000 5,480,000 10,970,000 1,170,000 142,000 1,312,000 12,282,000 1961 14,700,000 7,260,000 6,970,000 14,230,000 1,410,000 183,000 1,593,000 15,823,000 1962 11,600,000 3,940,000 4,120,000 8,060,000 948,000 106,000 1,054,000 9,114,000 1963 11,900,000 5,580,000 5,380,000 10,960,000 1,100,000 142,000 1,242,000 12,202,000 1964 12,700,000 7,900,000 7,090,000 14,990,000 1,310,000 197,000 1,507,000 16,497,000 1965 13,400,000 6,780,000 6,490,000 13,270,000 1,300,000 171,000 1,471,000 14,741,000 1966 13,000,000 6,800,000 6,320,000 13,120,000 1,240,000 172,000 1,412,000 14,532,000 1967 11,400,000 4,550,000 4,610,000 9,160,000 1,000,000 118,000 1,118,000 10,278,000 1968 13,100,000 6,640,000 6,310,000 12,950,000 1,250,000 170,000 1,420,000 14,370,000 1969 10,600,000 4,830,000 4,670,000 9,500,000 957,000 126,000 1,083,000 10,583,000 1970 14,700,000 8,640,000 8,020,000 16,660,000 1,520,000 213,000 1,733,000 18,393,000 1971 14,000,000 11,100,000 9,360,000 20,460,000 1,580,000 271,000 1,851,000 22,311,000 1972 12,200,000 5,280,000 5,230,000 10,510,000 1,100,000 136,000 1,236,000 11,746,000 1973 10,700,000 3,520,000 3,670,000 7,190,000 851,000 94,700 945,700 8,135,700 1974 10,500,000 2,860,000 3,170,000 6,030,000 789,000 79,800 868,800 6,898,800 1975 13,700,000 6,960,000 6,660,000 13,620,000 1,330,000 176,000 1,506,000 15,126,000 1976 12,500,000 4,710,000 4,840,000 9,550,000 1,080,000 123,000 1,203,000 10,753,000 1977 19,000,000 15,600,000 13,300,000 28,900,000 2,220,000 378,000 2,598,000 31,498,000 1978 12,900,000 4,990,000 5,080,000 10,070,000 1,120,000 129,000 1,249,000 11,319,000 1979 15,000,000 7,330,000 7,110,000 14,440,000 1,440,000 185,000 1,625,000 16,065,000 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.10 February 2013 Yentna River near Susitna Station – 15294345 cont. WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1980 18,900,000 13,400,000 11,700,000 25,100,000 2,080,000 324,000 2,404,000 27,504,000 1981 18,000,000 12,200,000 10,900,000 23,100,000 1,960,000 297,000 2,257,000 25,357,000 1982 13,500,000 6,430,000 6,190,000 12,620,000 1,260,000 164,000 1,424,000 14,044,000 1983 13,300,000 6,190,000 5,930,000 12,120,000 1,210,000 158,000 1,368,000 13,488,000 1984 14,500,000 7,450,000 7,100,000 14,550,000 1,410,000 187,000 1,597,000 16,147,000 1985 14,200,000 7,430,000 7,110,000 14,540,000 1,410,000 186,000 1,596,000 16,136,000 1986 14,200,000 6,570,000 6,460,000 13,030,000 1,340,000 166,000 1,506,000 14,536,000 1987 17,100,000 11,100,000 9,940,000 21,040,000 1,820,000 271,000 2,091,000 23,131,000 1988 16,600,000 9,270,000 8,700,000 17,970,000 1,680,000 232,000 1,912,000 19,882,000 1989 17,700,000 11,700,000 10,600,000 22,300,000 1,930,000 284,000 2,214,000 24,514,000 1990 19,100,000 12,200,000 11,200,000 23,400,000 2,070,000 297,000 2,367,000 25,767,000 1991 14,900,000 8,160,000 7,690,000 15,850,000 1,500,000 204,000 1,704,000 17,554,000 1992 13,300,000 5,480,000 5,480,000 10,960,000 1,170,000 144,000 1,314,000 12,274,000 1993 14,800,000 6,830,000 6,750,000 13,580,000 1,400,000 174,000 1,574,000 15,154,000 1994 14,300,000 6,240,000 6,190,000 12,430,000 1,310,000 159,000 1,469,000 13,899,000 1995 14,900,000 7,020,000 6,910,000 13,930,000 1,420,000 178,000 1,598,000 15,528,000 1996 10,000,000 2,780,000 3,070,000 5,850,000 762,000 76,800 838,800 6,688,800 1997 13,400,000 6,130,000 6,050,000 12,180,000 1,250,000 157,000 1,407,000 13,587,000 1998 14,100,000 7,140,000 6,920,000 14,060,000 1,390,000 180,000 1,570,000 15,630,000 1999 14,100,000 6,620,000 6,470,000 13,090,000 1,330,000 167,000 1,497,000 14,587,000 2000 15,300,000 8,130,000 7,710,000 15,840,000 1,520,000 203,000 1,723,000 17,563,000 2001 13,900,000 6,460,000 6,310,000 12,770,000 1,300,000 165,000 1,465,000 14,235,000 2002 12,400,000 5,000,000 5,080,000 10,080,000 1,100,000 130,000 1,230,000 11,310,000 2003 14,700,000 6,820,000 6,670,000 13,490,000 1,380,000 173,000 1,553,000 15,043,000 2004 13,700,000 6,160,000 6,120,000 12,280,000 1,280,000 157,000 1,437,000 13,717,000 2005 17,100,000 10,500,000 9,840,000 20,340,000 1,860,000 257,000 2,117,000 22,457,000 2006 14,500,000 7,780,000 7,410,000 15,190,000 1,460,000 194,000 1,654,000 16,844,000 2007 14,300,000 5,650,000 5,800,000 11,450,000 1,280,000 145,000 1,425,000 12,875,000 2008 13,100,000 5,130,000 5,240,000 10,370,000 1,150,000 133,000 1,283,000 11,653,000 2009 13,900,000 6,020,000 6,050,000 12,070,000 1,290,000 152,000 1,442,000 13,512,000 2010 14,800,000 6,900,000 6,840,000 13,740,000 1,420,000 174,000 1,594,000 15,334,000 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.11 February 2013 Table B.1-6. Annual Sediment Load for Pre-Project Conditions for Susitna River at Susitna Station Susitna River at Susitna Station - 15294350 WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1950 30,700,000 14,200,000 10,500,000 24,700,000 1,180,000 190,000 1,370,000 26,070,000 1951 34,300,000 18,300,000 12,500,000 30,800,000 1,470,000 244,000 1,714,000 32,514,000 1952 34,000,000 21,200,000 12,700,000 33,900,000 1,610,000 283,000 1,893,000 35,793,000 1953 37,800,000 20,100,000 13,700,000 33,800,000 1,620,000 268,000 1,888,000 35,688,000 1954 36,000,000 20,100,000 13,300,000 33,400,000 1,600,000 268,000 1,868,000 35,268,000 1955 36,400,000 22,800,000 13,700,000 36,500,000 1,730,000 304,000 2,034,000 38,534,000 1956 40,100,000 28,300,000 15,900,000 44,200,000 2,100,000 377,000 2,477,000 46,677,000 1957 37,800,000 22,300,000 14,100,000 36,400,000 1,740,000 297,000 2,037,000 38,437,000 1958 35,200,000 18,100,000 12,400,000 30,500,000 1,450,000 242,000 1,692,000 32,192,000 1959 37,400,000 24,800,000 14,400,000 39,200,000 1,860,000 330,000 2,190,000 41,390,000 1960 34,600,000 17,800,000 12,300,000 30,100,000 1,440,000 237,000 1,677,000 31,777,000 1961 37,800,000 21,100,000 13,800,000 34,900,000 1,660,000 281,000 1,941,000 36,841,000 1962 34,700,000 19,700,000 12,600,000 32,300,000 1,540,000 263,000 1,803,000 34,103,000 1963 34,100,000 19,900,000 12,600,000 32,500,000 1,540,000 265,000 1,805,000 34,305,000 1964 31,000,000 18,400,000 11,400,000 29,800,000 1,410,000 245,000 1,655,000 31,455,000 1965 35,700,000 20,600,000 13,100,000 33,700,000 1,610,000 275,000 1,885,000 35,585,000 1966 33,500,000 18,100,000 12,000,000 30,100,000 1,430,000 241,000 1,671,000 31,771,000 1967 32,700,000 17,800,000 11,800,000 29,600,000 1,410,000 237,000 1,647,000 31,247,000 1968 34,000,000 19,300,000 12,300,000 31,600,000 1,500,000 257,000 1,757,000 33,357,000 1969 24,200,000 9,610,000 7,720,000 17,330,000 821,000 128,000 949,000 18,279,000 1970 33,800,000 18,400,000 12,300,000 30,700,000 1,460,000 245,000 1,705,000 32,405,000 1971 34,600,000 23,100,000 13,200,000 36,300,000 1,710,000 307,000 2,017,000 38,317,000 1972 33,900,000 18,600,000 12,300,000 30,900,000 1,470,000 248,000 1,718,000 32,618,000 1973 29,900,000 13,100,000 9,950,000 23,050,000 1,090,000 174,000 1,264,000 24,314,000 1974 29,000,000 11,500,000 9,460,000 20,960,000 1,000,000 154,000 1,154,000 22,114,000 1975 33,400,000 18,900,000 12,100,000 31,000,000 1,480,000 252,000 1,732,000 32,732,000 1976 31,200,000 14,500,000 10,700,000 25,200,000 1,200,000 193,000 1,393,000 26,593,000 1977 40,500,000 28,800,000 15,900,000 44,700,000 2,110,000 383,000 2,493,000 47,193,000 1978 30,400,000 13,100,000 10,200,000 23,300,000 1,110,000 175,000 1,285,000 24,585,000 1979 38,900,000 23,700,000 14,600,000 38,300,000 1,820,000 316,000 2,136,000 40,436,000 APPENDIX B.1 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.1.12 February 2013 Susitna River at Susitna Station – 15294350 cont. WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1980 45,000,000 32,600,000 17,700,000 50,300,000 2,360,000 434,000 2,794,000 53,094,000 1981 40,300,000 29,400,000 15,800,000 45,200,000 2,110,000 390,000 2,500,000 47,700,000 1982 34,100,000 17,700,000 12,000,000 29,700,000 1,410,000 236,000 1,646,000 31,346,000 1983 31,700,000 14,200,000 10,700,000 24,900,000 1,180,000 189,000 1,369,000 26,269,000 1984 32,900,000 14,600,000 11,100,000 25,700,000 1,220,000 196,000 1,416,000 27,116,000 1985 34,200,000 19,300,000 12,500,000 31,800,000 1,510,000 257,000 1,767,000 33,567,000 1986 33,600,000 15,200,000 11,400,000 26,600,000 1,270,000 203,000 1,473,000 28,073,000 1987 39,700,000 25,800,000 15,100,000 40,900,000 1,920,000 343,000 2,263,000 43,163,000 1988 38,900,000 22,300,000 14,200,000 36,500,000 1,740,000 297,000 2,037,000 38,537,000 1989 40,900,000 27,400,000 15,900,000 43,300,000 2,050,000 365,000 2,415,000 45,715,000 1990 44,300,000 28,800,000 17,100,000 45,900,000 2,180,000 384,000 2,564,000 48,464,000 1991 34,900,000 19,700,000 12,700,000 32,400,000 1,540,000 263,000 1,803,000 34,203,000 1992 31,900,000 13,800,000 10,500,000 24,300,000 1,150,000 184,000 1,334,000 25,634,000 1993 38,500,000 22,400,000 14,300,000 36,700,000 1,750,000 298,000 2,048,000 38,748,000 1994 37,500,000 19,400,000 13,300,000 32,700,000 1,560,000 259,000 1,819,000 34,519,000 1995 37,200,000 20,100,000 13,500,000 33,600,000 1,610,000 268,000 1,878,000 35,478,000 1996 27,800,000 9,770,000 8,720,000 18,490,000 878,000 131,000 1,009,000 19,499,000 1997 32,300,000 16,700,000 11,400,000 28,100,000 1,340,000 223,000 1,563,000 29,663,000 1998 34,100,000 19,600,000 12,600,000 32,200,000 1,530,000 261,000 1,791,000 33,991,000 1999 33,700,000 17,600,000 11,900,000 29,500,000 1,400,000 235,000 1,635,000 31,135,000 2000 36,500,000 21,300,000 13,300,000 34,600,000 1,640,000 284,000 1,924,000 36,524,000 2001 34,000,000 17,700,000 12,000,000 29,700,000 1,410,000 236,000 1,646,000 31,346,000 2002 32,700,000 16,000,000 11,400,000 27,400,000 1,310,000 214,000 1,524,000 28,924,000 2003 38,000,000 19,800,000 13,500,000 33,300,000 1,590,000 265,000 1,855,000 35,155,000 2004 34,700,000 17,000,000 12,200,000 29,200,000 1,400,000 227,000 1,627,000 30,827,000 2005 44,400,000 31,400,000 17,700,000 49,100,000 2,340,000 418,000 2,758,000 51,858,000 2006 35,800,000 20,900,000 13,200,000 34,100,000 1,620,000 278,000 1,898,000 35,998,000 2007 35,100,000 15,500,000 12,000,000 27,500,000 1,320,000 207,000 1,527,000 29,027,000 2008 32,900,000 14,900,000 11,200,000 26,100,000 1,250,000 199,000 1,449,000 27,549,000 2009 34,500,000 16,300,000 12,000,000 28,300,000 1,360,000 217,000 1,577,000 29,877,000 2010 36,400,000 18,200,000 12,900,000 31,100,000 1,480,000 242,000 1,722,000 32,822,000 APPENDIX B.2. ANNUAL SEDIMENT LOAD TABULAR SUMMARY FOR MAXIMUM LOAD FOLLOWING OPERATIONS SCENARIO 1 Susitna-Watana Hydroelectric Project (FERC No. 14241) Development of Sediment Transport Relationships and an Initial Sediment Balance for the Middle and Lower Susitna River Segments Prepared for Alaska Energy Authority Prepared by Tetra Tech February 2013 APPENDIX B.2 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.2.1 February 2013 Table B.2-1. Annual Sediment Load for Max LF OS-1 Conditions for Susitna River at Gold Creek Susitna River at Gold Creek - 15292000 WY Water Volume (acre-ft)Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1950 6,130,000 19,900 92,100 112,000 8,480 67 8,547 120,547 1951 6,590,000 24,700 118,000 142,700 10,600 107 10,707 153,407 1952 6,540,000 24,700 119,000 143,700 10,600 122 10,722 154,422 1953 7,160,000 43,500 239,000 282,500 19,300 1,050 20,350 302,850 1954 6,980,000 42,200 237,000 279,200 18,100 1,520 19,620 298,820 1955 7,310,000 72,700 488,000 560,700 27,600 13,500 41,100 601,800 1956 8,270,000 103,000 681,000 784,000 41,100 11,100 52,200 836,200 1957 7,480,000 57,700 338,000 395,700 25,400 2,330 27,730 423,430 1958 6,840,000 44,600 264,000 308,600 18,500 2,980 21,480 330,080 1959 7,450,000 101,000 735,000 836,000 35,100 26,500 61,600 897,600 1960 6,990,000 47,700 287,000 334,700 19,400 4,170 23,570 358,270 1961 7,800,000 67,500 408,000 475,500 28,600 3,810 32,410 507,910 1962 8,350,000 100,000 643,000 743,000 42,000 7,740 49,740 792,740 1963 7,980,000 91,900 603,000 694,900 36,700 10,400 47,100 742,000 1964 7,070,000 41,300 224,000 265,300 18,300 857 19,157 284,457 1965 7,300,000 62,300 387,000 449,300 25,700 5,130 30,830 480,130 1966 6,810,000 30,400 152,000 182,400 13,200 276 13,476 195,876 1967 7,910,000 117,000 853,000 970,000 41,400 33,600 75,000 1,045,000 1968 7,100,000 43,900 245,000 288,900 19,200 1,410 20,610 309,510 1969 5,920,000 17,700 80,600 98,300 7,510 52 7,562 105,862 1970 4,980,000 20,500 100,000 120,500 8,880 115 8,995 129,495 1971 5,960,000 31,000 161,000 192,000 13,600 371 13,971 205,971 1972 7,870,000 65,600 386,000 451,600 28,900 2,650 31,550 483,150 1973 6,140,000 20,300 95,000 115,300 8,690 79 8,769 124,069 1974 6,410,000 22,800 108,000 130,800 9,790 93 9,883 140,683 1975 6,140,000 28,800 145,000 173,800 12,500 239 12,739 186,539 1976 6,210,000 20,600 96,300 116,900 8,820 76 8,896 125,796 1977 6,980,000 34,500 178,000 212,500 15,100 464 15,564 228,064 1978 6,100,000 19,400 89,400 108,800 8,260 63 8,323 117,123 1979 6,650,000 27,100 133,000 160,100 11,700 182 11,882 171,982 APPENDIX B.2 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.2.2 February 2013 Susitna River at Gold Creek – 15292000 cont. WY Water Volume (acre-ft)Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1980 7,690,000 77,800 505,000 582,800 31,000 9,850 40,850 623,650 1981 8,410,000 163,000 1,210,000 1,373,000 56,400 42,300 98,700 1,471,700 1982 6,960,000 41,900 239,000 280,900 17,500 2,200 19,700 300,600 1983 7,150,000 51,700 308,000 359,700 21,800 3,040 24,840 384,540 1984 6,930,000 44,200 254,000 298,200 18,800 2,120 20,920 319,120 1985 7,110,000 42,800 236,000 278,800 18,700 1,190 19,890 298,690 1986 6,190,000 20,200 94,000 114,200 8,640 70 8,710 122,910 1987 7,510,000 62,500 380,000 442,500 26,400 4,000 30,400 472,900 1988 7,390,000 52,400 302,000 354,400 23,100 1,920 25,020 379,420 1989 7,380,000 52,900 305,000 357,900 23,100 2,010 25,110 383,010 1990 9,330,000 154,000 1,060,000 1,214,000 60,300 22,000 82,300 1,296,300 1991 6,200,000 20,900 97,700 118,600 8,930 81 9,011 127,611 1992 6,250,000 21,200 99,200 120,400 9,070 80 9,150 129,550 1993 7,260,000 58,500 362,000 420,500 23,900 5,260 29,160 449,660 1994 7,210,000 45,900 257,000 302,900 20,200 1,330 21,530 324,430 1995 7,390,000 53,200 308,000 361,200 23,200 2,130 25,330 386,530 1996 6,130,000 19,700 91,400 111,100 8,420 67 8,487 119,587 1997 5,990,000 25,100 123,000 148,100 10,800 146 10,946 159,046 1998 6,280,000 25,100 122,000 147,100 10,800 130 10,930 158,030 1999 6,370,000 22,400 105,000 127,400 9,600 89 9,689 137,089 2000 7,300,000 48,100 272,000 320,100 21,000 1,710 22,710 342,810 2001 6,900,000 39,200 217,000 256,200 16,800 1,340 18,140 274,340 2002 6,170,000 20,300 94,600 114,900 8,690 72 8,762 123,662 2003 7,330,000 57,900 349,000 406,900 24,300 3,670 27,970 434,870 2004 6,850,000 35,200 186,000 221,200 15,500 608 16,108 237,308 2005 8,720,000 110,000 711,000 821,000 46,300 8,740 55,040 876,040 2006 7,340,000 82,600 577,000 659,600 29,800 18,700 48,500 708,100 2007 6,930,000 35,300 185,000 220,300 15,500 575 16,075 236,375 2008 6,430,000 25,200 124,000 149,200 10,900 231 11,131 160,331 2009 6,850,000 34,700 184,000 218,700 15,100 727 15,827 234,527 2010 7,310,000 51,900 300,000 351,900 22,700 2,050 24,750 376,650 APPENDIX B.2 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.2.3 February 2013 Table B.1-2. Annual Sediment Load for Max LF OS-1 Conditions for Susitna River at Sunshine Susitna River at Sunshine - 15292780 WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1950 14,500,000 3,130,000 2,580,000 5,710,000 136,000 83,300 219,300 5,929,300 1951 16,200,000 4,140,000 3,250,000 7,390,000 156,000 96,700 252,700 7,642,700 1952 16,300,000 5,070,000 3,660,000 8,730,000 160,000 127,000 287,000 9,017,000 1953 17,700,000 5,030,000 3,920,000 8,950,000 176,000 112,000 288,000 9,238,000 1954 17,200,000 5,030,000 3,840,000 8,870,000 170,000 116,000 286,000 9,156,000 1955 17,700,000 6,440,000 4,570,000 11,010,000 180,000 191,000 371,000 11,381,000 1956 20,000,000 8,590,000 5,950,000 14,540,000 212,000 228,000 440,000 14,980,000 1957 18,200,000 5,980,000 4,450,000 10,430,000 185,000 136,000 321,000 10,751,000 1958 16,600,000 4,710,000 3,600,000 8,310,000 163,000 124,000 287,000 8,597,000 1959 18,200,000 7,370,000 5,110,000 12,480,000 189,000 241,000 430,000 12,910,000 1960 17,100,000 4,820,000 3,720,000 8,540,000 168,000 125,000 293,000 8,833,000 1961 19,000,000 6,370,000 4,720,000 11,090,000 194,000 159,000 353,000 11,443,000 1962 19,900,000 8,620,000 5,910,000 14,530,000 211,000 243,000 454,000 14,984,000 1963 19,300,000 7,890,000 5,510,000 13,400,000 202,000 212,000 414,000 13,814,000 1964 16,400,000 5,800,000 4,050,000 9,850,000 164,000 156,000 320,000 10,170,000 1965 18,600,000 6,720,000 4,810,000 11,530,000 190,000 168,000 358,000 11,888,000 1966 17,100,000 5,130,000 3,800,000 8,930,000 169,000 126,000 295,000 9,225,000 1967 19,200,000 8,190,000 5,630,000 13,820,000 202,000 267,000 469,000 14,289,000 1968 17,800,000 5,920,000 4,290,000 10,210,000 179,000 143,000 322,000 10,532,000 1969 12,000,000 1,570,000 1,550,000 3,120,000 103,000 67,200 170,200 3,290,200 1970 13,700,000 3,600,000 2,820,000 6,420,000 133,000 82,700 215,700 6,635,700 1971 16,900,000 6,630,000 4,470,000 11,100,000 174,000 175,000 349,000 11,449,000 1972 19,200,000 6,850,000 4,950,000 11,800,000 197,000 167,000 364,000 12,164,000 1973 15,400,000 3,840,000 2,980,000 6,820,000 146,000 102,000 248,000 7,068,000 1974 15,000,000 3,260,000 2,700,000 5,960,000 141,000 87,700 228,700 6,188,700 1975 17,100,000 5,600,000 4,070,000 9,670,000 172,000 123,000 295,000 9,965,000 1976 15,200,000 3,480,000 2,810,000 6,290,000 143,000 89,800 232,800 6,522,800 1977 17,600,000 5,680,000 4,110,000 9,790,000 175,000 139,000 314,000 10,104,000 1978 15,000,000 2,990,000 2,540,000 5,530,000 139,000 82,100 221,100 5,751,100 1979 17,100,000 5,210,000 3,830,000 9,040,000 169,000 124,000 293,000 9,333,000 APPENDIX B.2 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.2.4 February 2013 Susitna River at Sunshine – 15292780 cont. WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1980 18,800,000 6,530,000 4,780,000 11,310,000 192,000 179,000 371,000 11,681,000 1981 20,300,000 10,000,000 6,590,000 16,590,000 217,000 377,000 594,000 17,184,000 1982 17,400,000 5,440,000 4,010,000 9,450,000 173,000 138,000 311,000 9,761,000 1983 17,000,000 4,710,000 3,690,000 8,400,000 167,000 123,000 290,000 8,690,000 1984 17,000,000 5,000,000 3,760,000 8,760,000 167,000 138,000 305,000 9,065,000 1985 17,500,000 5,700,000 4,160,000 9,860,000 176,000 138,000 314,000 10,174,000 1986 14,900,000 3,020,000 2,570,000 5,590,000 139,000 82,600 221,600 5,811,600 1987 19,200,000 6,490,000 4,770,000 11,260,000 196,000 163,000 359,000 11,619,000 1988 18,000,000 5,510,000 4,190,000 9,700,000 180,000 124,000 304,000 10,004,000 1989 18,400,000 5,850,000 4,380,000 10,230,000 186,000 136,000 322,000 10,552,000 1990 22,900,000 10,100,000 7,130,000 17,230,000 248,000 282,000 530,000 17,760,000 1991 15,700,000 3,820,000 3,020,000 6,840,000 150,000 96,100 246,100 7,086,100 1992 15,600,000 4,030,000 3,110,000 7,140,000 150,000 96,200 246,200 7,386,200 1993 18,800,000 6,360,000 4,660,000 11,020,000 191,000 154,000 345,000 11,365,000 1994 18,200,000 5,370,000 4,100,000 9,470,000 181,000 128,000 309,000 9,779,000 1995 18,300,000 5,640,000 4,290,000 9,930,000 184,000 127,000 311,000 10,241,000 1996 14,100,000 2,400,000 2,170,000 4,570,000 127,000 77,100 204,100 4,774,100 1997 16,400,000 4,770,000 3,580,000 8,350,000 161,000 109,000 270,000 8,620,000 1998 17,300,000 5,460,000 3,980,000 9,440,000 172,000 122,000 294,000 9,734,000 1999 17,300,000 5,040,000 3,740,000 8,780,000 170,000 121,000 291,000 9,071,000 2000 19,200,000 6,850,000 4,870,000 11,720,000 196,000 168,000 364,000 12,084,000 2001 17,200,000 4,880,000 3,740,000 8,620,000 170,000 120,000 290,000 8,910,000 2002 15,700,000 3,820,000 3,030,000 6,850,000 150,000 94,500 244,500 7,094,500 2003 18,500,000 5,680,000 4,310,000 9,990,000 185,000 138,000 323,000 10,313,000 2004 17,000,000 4,470,000 3,530,000 8,000,000 166,000 99,700 265,700 8,265,700 2005 22,200,000 9,900,000 6,860,000 16,760,000 240,000 244,000 484,000 17,244,000 2006 17,900,000 6,390,000 4,590,000 10,980,000 182,000 199,000 381,000 11,361,000 2007 17,100,000 4,160,000 3,410,000 7,570,000 166,000 98,600 264,600 7,834,600 2008 15,900,000 3,690,000 3,010,000 6,700,000 152,000 92,100 244,100 6,944,100 2009 16,900,000 4,250,000 3,420,000 7,670,000 164,000 98,800 262,800 7,932,800 2010 18,000,000 5,160,000 4,020,000 9,180,000 179,000 120,000 299,000 9,479,000 APPENDIX B.2 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.2.5 February 2013 Table B.2-3. Annual Sediment Load for Max LF OS-1 Conditions for Susitna River at Susitna Station Susitna River at Susitna Station - 15294350 WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1950 31,100,000 10,900,000 9,710,000 20,610,000 982,000 148,000 1,130,000 21,740,000 1951 34,300,000 13,800,000 11,300,000 25,100,000 1,210,000 187,000 1,397,000 26,497,000 1952 33,600,000 15,100,000 11,300,000 26,400,000 1,260,000 204,000 1,464,000 27,864,000 1953 37,600,000 15,700,000 12,700,000 28,400,000 1,380,000 215,000 1,595,000 29,995,000 1954 36,000,000 15,500,000 12,200,000 27,700,000 1,340,000 213,000 1,553,000 29,253,000 1955 36,300,000 17,200,000 12,500,000 29,700,000 1,440,000 238,000 1,678,000 31,378,000 1956 40,000,000 21,700,000 14,600,000 36,300,000 1,780,000 302,000 2,082,000 38,382,000 1957 37,800,000 17,300,000 13,000,000 30,300,000 1,470,000 238,000 1,708,000 32,008,000 1958 35,200,000 14,100,000 11,500,000 25,600,000 1,230,000 193,000 1,423,000 27,023,000 1959 37,200,000 18,900,000 13,200,000 32,100,000 1,560,000 263,000 1,823,000 33,923,000 1960 34,600,000 13,700,000 11,400,000 25,100,000 1,210,000 188,000 1,398,000 26,498,000 1961 37,800,000 16,700,000 12,900,000 29,600,000 1,440,000 231,000 1,671,000 31,271,000 1962 34,700,000 14,300,000 11,600,000 25,900,000 1,280,000 204,000 1,484,000 27,384,000 1963 34,100,000 14,700,000 11,500,000 26,200,000 1,280,000 207,000 1,487,000 27,687,000 1964 30,900,000 12,700,000 10,100,000 22,800,000 1,100,000 174,000 1,274,000 24,074,000 1965 35,600,000 16,000,000 12,100,000 28,100,000 1,360,000 221,000 1,581,000 29,681,000 1966 33,500,000 13,600,000 11,000,000 24,600,000 1,180,000 186,000 1,366,000 25,966,000 1967 32,500,000 12,800,000 10,700,000 23,500,000 1,170,000 185,000 1,355,000 24,855,000 1968 34,000,000 14,400,000 11,300,000 25,700,000 1,240,000 198,000 1,438,000 27,138,000 1969 26,100,000 8,050,000 7,660,000 15,710,000 742,000 110,000 852,000 16,562,000 1970 33,200,000 14,900,000 11,300,000 26,200,000 1,260,000 201,000 1,461,000 27,661,000 1971 33,200,000 15,800,000 11,400,000 27,200,000 1,300,000 215,000 1,515,000 28,715,000 1972 33,900,000 14,600,000 11,400,000 26,000,000 1,260,000 203,000 1,463,000 27,463,000 1973 30,200,000 9,720,000 9,160,000 18,880,000 896,000 132,000 1,028,000 19,908,000 1974 29,800,000 9,060,000 8,940,000 18,000,000 857,000 124,000 981,000 18,981,000 1975 32,100,000 13,300,000 10,600,000 23,900,000 1,140,000 181,000 1,321,000 25,221,000 1976 31,500,000 11,300,000 9,910,000 21,210,000 1,010,000 153,000 1,163,000 22,373,000 1977 40,200,000 22,100,000 14,500,000 36,600,000 1,750,000 299,000 2,049,000 38,649,000 1978 30,600,000 10,400,000 9,460,000 19,860,000 946,000 141,000 1,087,000 20,947,000 1979 38,600,000 18,400,000 13,400,000 31,800,000 1,520,000 248,000 1,768,000 33,568,000 APPENDIX B.2 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.2.6 February 2013 Susitna River at Susitna Station – 15294350 cont. WY Water Volume (acre-ft) Suspended Load Bed Load Total LoadSilt/Clay Sand Total Sand Gravel Total 1980 44,800,000 26,600,000 16,600,000 43,200,000 2,070,000 364,000 2,434,000 45,634,000 1981 40,100,000 23,100,000 14,700,000 37,800,000 1,840,000 327,000 2,167,000 39,967,000 1982 34,000,000 14,200,000 11,200,000 25,400,000 1,220,000 195,000 1,415,000 26,815,000 1983 31,700,000 10,700,000 9,840,000 20,540,000 990,000 149,000 1,139,000 21,679,000 1984 32,900,000 11,400,000 10,300,000 21,700,000 1,040,000 158,000 1,198,000 22,898,000 1985 34,200,000 14,700,000 11,400,000 26,100,000 1,260,000 202,000 1,462,000 27,562,000 1986 33,600,000 12,000,000 10,600,000 22,600,000 1,080,000 163,000 1,243,000 23,843,000 1987 39,600,000 21,300,000 14,100,000 35,400,000 1,690,000 291,000 1,981,000 37,381,000 1988 38,900,000 17,400,000 13,200,000 30,600,000 1,480,000 238,000 1,718,000 32,318,000 1989 40,800,000 23,400,000 14,900,000 38,300,000 1,830,000 318,000 2,148,000 40,448,000 1990 44,200,000 23,000,000 16,100,000 39,100,000 1,930,000 325,000 2,255,000 41,355,000 1991 34,900,000 15,400,000 11,700,000 27,100,000 1,300,000 208,000 1,508,000 28,608,000 1992 31,800,000 10,300,000 9,680,000 19,980,000 948,000 140,000 1,088,000 21,068,000 1993 38,400,000 17,900,000 13,300,000 31,200,000 1,520,000 247,000 1,767,000 32,967,000 1994 37,500,000 15,400,000 12,500,000 27,900,000 1,350,000 211,000 1,561,000 29,461,000 1995 37,100,000 15,800,000 12,500,000 28,300,000 1,370,000 217,000 1,587,000 29,887,000 1996 29,000,000 8,100,000 8,490,000 16,590,000 786,000 111,000 897,000 17,487,000 1997 31,900,000 12,500,000 10,300,000 22,800,000 1,090,000 170,000 1,260,000 24,060,000 1998 33,600,000 14,400,000 11,200,000 25,600,000 1,230,000 195,000 1,425,000 27,025,000 1999 33,400,000 13,000,000 10,800,000 23,800,000 1,130,000 176,000 1,306,000 25,106,000 2000 36,300,000 16,000,000 12,200,000 28,200,000 1,360,000 219,000 1,579,000 29,779,000 2001 34,000,000 13,400,000 11,000,000 24,400,000 1,170,000 183,000 1,353,000 25,753,000 2002 32,700,000 12,300,000 10,500,000 22,800,000 1,090,000 166,000 1,256,000 24,056,000 2003 37,900,000 15,600,000 12,700,000 28,300,000 1,370,000 215,000 1,585,000 29,885,000 2004 34,700,000 13,200,000 11,200,000 24,400,000 1,180,000 180,000 1,360,000 25,760,000 2005 44,300,000 24,800,000 16,500,000 41,300,000 2,020,000 344,000 2,364,000 43,664,000 2006 35,700,000 15,800,000 12,100,000 27,900,000 1,360,000 221,000 1,581,000 29,481,000 2007 35,100,000 12,500,000 11,200,000 23,700,000 1,140,000 171,000 1,311,000 25,011,000 2008 32,800,000 11,500,000 10,300,000 21,800,000 1,040,000 156,000 1,196,000 22,996,000 2009 34,500,000 12,600,000 11,100,000 23,700,000 1,140,000 172,000 1,312,000 25,012,000 2010 36,400,000 14,400,000 12,000,000 26,400,000 1,280,000 198,000 1,478,000 27,878,000 APPENDIX B.2 SEDIMENT-TRANSPORT RELATIONSHIPS/SEDIMENT BALANCE Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page B.2.7 February 2013