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HomeMy WebLinkAboutAPA4754 '75 -·------ SUSITNA HYDROELECTRIC PROJECT FEDERAL ENERGY REGULATORY COMMISSION PROJECT No. 7114 RESERVOIR AND RIVER SEDIMENTATION [}{]~[R1Z£~=~[ID~~©@ I SUSITNA JOINT VENTURE FINAL REPORT APRIL 1984 DOCUMENT No. 475 __ ALASKA POWER AUTHORITY_------~ Document No. 475 Susitna File No. 42.2.6 SUSI"ftiA HYDROELECTRiC PROJF.Cr RESERVOIR AND RIVER SEDIMENTATION Report by Harza-Ebasco Susitna Joint Venture Prepared for Alaska Power Authority Final Report April 1984 ARLIS Alaska Resources Library & InformatiOn Servtces Anchorage, Alaska [t PtlS (n , ,. .... ""'{) ftf~~ no, if? 5 NOTICE ANY QUESTIONS OR COMMENTS tONCERNING THIS REPORT SHOULD BE DIRECTED TO THE ALASKA POWER AUTHORITY SUSITNA PROJECT OFFICE ARLIS Alaska Resources ~, . &. lnformatlOfl Services ""''rary ka ~ P...nchorage. Alas ,...... 0 co ,...... co M 0 0 0 LO LO ,...... M M TABLE OF CORTENTS SECTION/TITLE 1.0 SCOPE OF STUDY 2.0 SUMMARY AND CONCLUSIONS 3.0 RECOMMENDATIONS 4.0 PROJECT SETTING 5.0 REVIEWS OF PREVIOUS STUDIES 6.0 DATA SOURCES 6.1 Streamflow 6.2 River Cross Sections 6.3 Bedload and Bed Material 6.4 Suspended Sediment 7.0 RESERVOIR SEDIMENTATION 7.1 General Approach 7. 2 Sediment Load 7.3 Reservoir Sediment Inflow 7. 4 Sediment Trap Efficiency 7 .5 Sediment Deposit 7.6 Turbidity 8.0 DOWNSTREAM AGGRADATION AND DEGRADATION 8.1 General Approach 8.2 Middle Reach 8.2 .1 8.2.2 8.2 .3 8.2.4 8.2 .5 8.2.6 Dominant Discharge Bed Material Tributaries and Sloughs Degradation Limited by Armoring Aggradation near Tributary Mouths Other Project Effects 8.3 Lower Reach 8.3 .1 8.3.2 8.3 .3 8.3.4 8.3 .5 8.3.6 8.3 .7 REFERENCES TABLES EXHIBITS Cross Sections Bedload Discharge Rating Curves Suspended Sediment Discharge Rating Curves Particle Size of Bedload Bed Material Balance of Total Sediment Inflow and Outflow Project Effect -i- PAGE 1-1 2-1 3-1 4-1 5-1 6-1 6-1 6-2 6-3 7-1 7-1 7-1 7-2 7-3 7-5 7-6 8-1 8-1 8-2 8-2 8-3 8-4 8-4 8-5 8-6 8-6 8-7 8-7 8-9 8-9 8-10 8-11 8-13 LIST OF TABLES No. Title 1 River Bed Degradation, Armoring Size and Bed Material Size 2 Reservoir Trap Efficiency by Brune's Curves 3 Reservoir Trap Efficiency by Churchill's Curves 4 Bed Material Size Distribution, Samples Collected by Harza-Ebasco 5 Tributary Floods and Bed Material Sizes 6 Bedload Discharge and Size Distribution, Susitna River near Talkeetna, Alaska 7 Bedload Discharge and Size Distribution, Chulitna River near Talkeetna, Alaska 8 Bedload Discharge and Size Distribution, Talkeetna River near Talkeetna, Alaska 9 Bedload Discharge and Size Distribution, Susitna River at Sunshine, Alaska 10 Bed Material Size Distribution, Susitna River near Talkeetna, Alaska 11 Bed Material Size Distribution, Chulitna River near Talkeetna, Alaska 12 Bed Material Size Distribution, Talkeetna River near Talkeetna, Alaska 13 Bed Material Size Distribution, Susitna River at Sunshine, Alaska -.:ii- LIST OF EXHIBITS No. Title 1 Susitna River Basin and Gaging Stations 2 River Profiles 3 Locations of Bed Material Samples Collected by Harza-Ebasco 4 Suspended Sediment Rating Curve, Susitna River near Cantwell 5 Flow Duration Curves, Susitna River near Cantwell and at Gold Creek 6 Suspended Sediment Rating Curve, Susitna River at Gold Creek 7 Susitna River, Cross Sections and Subreaches 8 Susitna River, Size Distribution of Bed Material 9 Susitna River, Cross Section 1 10 Susitna River, Cross Section 2 11 River Cross Sections, Susitna River near Talkeetna 12 River Cross Sections, Susitna River at Sunshine 13 River Cross Sections, Susitna River at Upstream from Sunshine Bridge 14 River Cross Sections, Chulitna River near Talkeetna 15 River Cross Sections, Talkeetna River near Talkeetna 16 Bedload Discharge Rating Curve, Susitna River near Talkeetna 17 Bedload Discharge Rating Curve, Talkeetna River near Talkeetna 18 Bedload Discharge Rating Curve, Susitna River at Sunshine 19 Bedload Discharge Rating Curve, Chulitna River near Talkeetna 20 Suspended Sediment Rating Curve, Susitna River near Talkeetna 21 Suspended Sediment Rating Curve, Chulitna River near Talkeetna -iii- LIST OF EXHIBITS (Cont'd) No. Title 22 Suspended Sediment Rating Curve, Talkeetna River near Talkeetna 23 Suspended Sediment Rating Curve, Susitna River at Sunshine 24 Size Distribution of Bedload, Susitna River near Talkeetna 25 Size Distribution of Bedload, Chulitna River near Talkeetna 26 Size Distribution of Bedload, Talkeetna River near Talkeetna 27 Size Distribution of Bedload, Susitna River at Sunshine 28 Duration Curves based on Daily Flows, Water Year 1982, Susitna River at Gold Creek and Sunshine 29 Duration Curves based on Daily Flows, Water Year 1982, Chulitna and Talkeetna Rivers -iv- 1.0 SCOPE OF THE STUDY The scope of the present study includes a reservoir sedimentation analysis for Watana and Devil Canyon Reservoirs, and a river sediment transport study for the Susitna River between the Devil Canyon dam site and the Sunshine stream gaging station (see Exhibit 1 for the locations). The major tasks are: 1. to review available relevant reports, 2. to estimate sediment inflow to the reservoirs and sediment deposit in the reservoirs for 50 and 100 years of reservoir operation, 3. to conduct a preliminary assessment of aggradation and degradation near the mouths of the tributaries and sloughs in the study reach; 4. to recommend areas of concern for further study; and 5. to recommend a program of data collection required for further study. 1-1 2.0 SUMMARY AND CONCLUSIONS Sediment inflow to Watana and Devil Canyon Reservoirs were estimated by transposing sediment discharge data for the Susitna River near Cantwell and at Gold Creek. Suspended-sediment discharges at the gaging stations were computed by the sediment rating-flow duration curve method. Bedload dis- charges were estimated as a percentage of suspended sediment discharges. Sediment deposits in the reservoirs were estimated by assuming 100 percent trap efficiency. Sediment deposit in Watana Reservoir was estimated to be 6, 730,000 tons per year (tons/yr) or 210,000 acre-feet (af) for a 50-year period. The 100-year deposit would be about 410,000 af. The gross reservoir volume is about 9,470,000 af at a normal maximum pool elevation of 2,185 feet(ft), of which about 5,730,000 af is the dead storage. The 100-year sediment deposit is only about 7 percent of the dead storage volume. Without Watana Reservoir, sediment deposit in Devil Canyon Reservoir was estimated to be 7,240,000 tons/yr or 226,000 a£ for a 50-year period. The 100-year deposit would be about 442,000 af. With Watana Reservoir in operation, sediment deposit in Devil Canyon Reservoir would be about 515,000 tons/yr or 16,100 af for a 50-year period assuming that Watana Reservoir would trap all sediment inflow except insig- nificant amount of very fine material. Tne 100-year deposit would be about 31,400 af. The gross volume of Devil Canyon Reservoir is about 1,090,000 af at a normal maximum pool elevation of 1,455 ft, of which about 740,000 af is the dead storage. The 100-year sediment deposit is about 4 and 60 percent of the dead storage for with and without Watana Reservoir, respectively. 2-1 The river sedimentation studies below Devil Canyon Dam cover the Susitna River from its confluence with Portage Creek to the Sunshine gage. This river segment was divided into the Middle and Lower reaches for analysis. The Middle reach runs from the confluence with Portage Creek to the con- fluence with the Chulitna River and the Lower reach from the confluence with the Chulitna River to the Sunshine gage. The :t-1iddle reach was divided further into 12 subreaches for estimating post- project degradation. The degradation for each subreach was computed by assuming no bedload inflow to the subreach and assuming that bed armoring will develop as small particles are sorted out and transported downstream. Table 1 lists the estimated degradations and provides a comparison between armoring sizes under natural and with-project conditions, and existing bed material size distributions. conditions are considerably The estimated armoring sizes for with-project smaller than those for natural conditions discharge (l)ll due to reservoir regula-because of the smaller dominent tion. The dominant discharges were taken as the mean annual flood for the natural and with-project conditions. The channel degradation was computed using the procedures given in "Design of Small Dams" (1) and ranges from zero to 0.3 ft in various subreaches. Since bedload from tributaries and upstream subreaches could deposit in a subreach, the net degradation would be smaller. River bed aggradation near the mouths of some tributaries appears to be likely under with-project conditions. This conclusion is based on a compa- rison of sediment size transportable by the Susitna River under with-project conditions with the bed material size distribution near the mouth of the tributaries. 1J See list of references at the end of the text. 2-2 The sediment transportable under with-project condition were assumed to be equal to or smaller than the corresponding armoring size shown in Table 1. The median sizes (Dso) of bed material at the mouths of Indian River and Sherman Creek are greater than the transportable sizes. Thus, coarser ma- terial brought down by these tributaries will have the tendency to accumu- late in the mainsteam near the tributary confluences. The size distributions of bed material for other tributaries (Table 1) indi- cate Dso smaller than the transportable size, and there would be less aggra- dation near the mouth of these tributaries. However, because only a few bed material samples were collected in the study reach as discussed under the section entitled "Bed Material", additional data will have to be collected and analyzed to confirm or revise this assessment. The current analysis indicates that there may be aggradation at the mouths of some tributaries, although this is not expected to be severe. The need for substantial mitigation measures is not anticipated. Further analyses will be made to estimates the extent of potential aggradation. For this purpose a sediment data collection program has been proposed by the U.S. Geological Survey (USGS) which includes sediment measurements on Indian River and Portage Creek. When data collected under this program become available, a quantitative estimation may become feasible. Most of the tributaries will adjust to new flow regime without detrimental effects on fish access, bridge or railroad. The adjustment will depend upon a number of factors such as the shape of a tributary cross section, size of bed material, increase in the hydraulic gradient due to lowering of water surface elevation in the mainstem under with-project conditions, magnitude and frequency of high flows in a tributary and the size of sediment trans- portable by the mainstem flow. The interaction of these factors is not completely understood. Therefore, depending upon these factors, a tributary may adjust to a new regime over a period of one wet season or a number of years. 2-3 Bed material samples collected by Harza-Ebasco in side channels and on slough berms indicate that under the natural conditions, erosion of side channels and berms at the entrance of sloughs occur during high flowsc Under with-project conditions, the erosion will be less and some aggradation at the entrance of the sloughs and side channels may be expected. This is because the main river channel will become more confined and any occasional higher flows may deposit bedload near the entrance. This in conjunct ion with attenuation of high flows by the reservoir will reduce the frequency of mainstem flows overtopping the berms. Project effect on sediment transport in the Lower reach will depend primari- ly on the change in the bedload transporting capacity of the Susitna River below its confluence with the Chulitna and Talkeetna Rivers. The sum of bedload discharges estimated for the Susitna River near Talkeetna (about 5 miles above the confluence with the Chulitna River), the Chulitna River near Talkeetna (about 17 miles above the confluence) and the Talkeetna River near Talkeetna (about 4 miles above the confluence) in water year 1982 was about 1,460,000 tons. The Susitna River contributes 3 percent of the total bedload, the Chulitna River 83 percent, and the Talkeetna River 14 percent. In the same year, bedload passing Sunshine (about 14 miles down- stream from the confluence) was estimated to be 423,000 tons. The locations of the gaging stations at which the bedloads were calculated are shown on Exhibit 1. The bedload discharges were computed by the sediment rating-flow duration curve method. The sediment rating curves at the gaging stations were devel- oped using bedload samples collected by the USGS during the summer months of 1981 and 1982 (Exhibits 16,17, 18,and 19). The sediment rating curves are not well defined, especially the curve for the Chulitna River, because of large scattering of the data points. tainty in the above estimated rates. 2-4 This introduces some degree of uncer- The sum of suspended sediment discharges for the Susitna River near Talkeet- na, the Chulitna River near Talkeetna and the Talkeetna River near Talkeetna was estimated to be about 11,660,000 tons in water year 1982. The suspended sediment discharge for the Susitna River near Sunshine was estimate to be about 13,330,000 tons for the corresponding period. Therefore, the total sediment loads (suspended sediment load + bedload) entering and leaving the Lower reach were about 13,120,000 and 13,753,000 tons, respectively. The river cross sections (Exhibit 9 through 15) indicate periodic scour and deposition. Based on field reconnaissance, the Lower reach appears to be in a long-term stable regime. Therefore, the imbalance of 633,000 tons indi- cated in water year 1982 is likely to be because of contribution of sediment from intervening area between the sediment measuring stations or because of error in the estimation of sediment discharge at the gaging stations. Computations show that the total sediment discharge capacity at Sunshine under with-project conditions would be about 55 percent of that under natural conditions. Therefore, with 80 percent of the total load coming from the Chulitna and Talkeetna Rivers, long-term aggradation in the Lower reach can be expected because of regulation of flood and high flows by the reservoirs. It is expected that the aggradation will start at the mouth of the Chulitna River. Existing delta formation will further develop and extend towards the left bank below the confluence but the river channel will become better defined compared to existing conditions. This is because the flow in the river will be much more stable under with-project conditions than under natural conditions. Aggradation is unlikely to cause severe navigational or fish access problems in the reach below the confluence. This is because the major flow contribu- tion (average annual flows at Sunshine and Susitna Station are about 2.5 and 5 times that at Gold Creek) comes from the drainage basin below the 2-5 confluence which will provide adequate river stages for navigation or fish access. The USGS has collected more data on bedload discharge during 1983 and also will collect data during 1984. When these data become available, a better estimation of potential aggradation may become possible. 2-6 3.0 RKCOMMKBDATIOR This chapter contains recommendations for further study in order to: 1. refine estimates of aggradation downstream of the Chulitna- Susitna confluence. 2. refine estimates of aggreadation at tributary mouths, and 3. refine estimates of channel stability upstream of the Susitna- Chulitna confluence. The 19~3-84 sediment sampling program of the USGS includes a new bedload measurement station on the Susitna River below the confluence of the Chulit- na and Susitna rivers. This will permit refinement in the analysis of bed- load transport in the Chulitna River and also will help to identify the location of sediment deposits in the Lower reach. The USGS also will conduct a bedload and bed material sampling program for the Indian River and Portage Creek. This will help in evaluating the aggra- dation or downcutting to new base elevation near the mouth of these tribu- taries under with-project conditions. For each major tributary of concern, about S cross sections on the tributary (at the confluence and upstream from the confluence) and two cross sections (upstream and downstream from the confluence) on the mainstream should be surveyed to determine the gradient of the tributary. This will help in the computations of aggradation or degradation in the tributaries near their confluenc·e with the main stream. The USGS sediment sampling program should be continued for a period of at least 3 to 5 years. The size distribution of bed material used in this analysis is based on small number of samples taken near the surface and may not represent the sub-pavement materials. Therefore, bed material samples in the twelve subreaches identified in this study should be taken both for pavement sand sub-pavement. 3-l Streamflow data of the tributaries are not available and hence the estimates of bedload transported by the tributarief? could not be made. A stage re- corder and periodic discharge measurements are recommended for the Indian River. These data can be used with results of the USGS sampling program to estimate the bedload transported by the river. The information obtained from these data also can be transposed to other tributaries to estimate amount of bedload brought into the Susitna River. l-2 4.0 PROJECT SETTING The Susitna River drains about 19,600 square miles (sq mi) in the southcen- tral region of Alaska. Major tributaries include the Chulitna, Talkeeta, and Yentna rivers. Glaciers in the headwaters contribute substantial sedi- ment during summer months. Streamflow is characterized by turbid high flows from ice breakup in May to September and clear low flows from October to April. High summer flows are caused by glacial melt, snowmelt, and storm rainfall. The Susitna River is about 320 mile (mi) long. The Watana and Devil Canyon damsites are located at river miles 184 and 152, respectively. The drainage areas at the two dams are about 5180 sq mi and 5810 sq mi, respectively. The Chulitna River originates in the glaciers on the south slopes of Mount McKinley and enters the Susitna River from the west near Talkeetna at river mile 98. The Talkeetna River originates in the Talkeetna Mountain and en- ters the Susitna River from the east near Talkeetna at river mile 97. The Yentna River originates in the glaciers of the Alaska range and enters the Susitna River from the west at river mile 28. The Susitna River falls from elevation (El.) 850 ft at the Devil Canyon dam- site to El. 260 ft at the Sunshine gage (Exhibit 2). The average slope in this reach is about 0.0017. The Susitna River between the Devil Canyon damsite and the Susitna-Chulitna confluence has many side channels, sloughs, and islands, while most of the reach of the river below the confluence is highly braided. 4-1 5.0 REVIEW OF PREVIOUS STUDIES Reports of previous studies related to reservoir sedimentation, turbidity and channel stability were reviewed. The studies from which the basic data and results were used in the present study include the following: 1. R&M Consultant, Inc. "Susitna Hydroelectric Project, River Morphology," prepared for Acres American Inc. January 1982 (2). This study provides an overview of the climate, topography, geology, soils, vegetation and available water resources in the Susitna River basin. Poten- tial changes in the present river morphology under with project conditions also are discussed. Estimates of available streamflow are provided as monthly flow duration curves under natural and with-project conditions. Flow variability is dis- cussed by presenting 1-, 3-, 7-and 15-day high and low flow values for May through October period. Mean annual floods are estimated for all major tributaries. Discharge and stage frequency curves are given for key loca- tions on the Susitna River under natural and with-project conditions. Sediment characteristics of the Susitna River are discussed and sediment rating curves are provided for the stream gaging stations on the Susitna, Talkeetna, Chulitna and Maclaren rivers. Bedload of the Susitna River at Denali is reported to be about 1, 588,000 tons per year.. This estimate appears to be high probably because of uncertainty in bedload discharge rating curve. ·Size distribution of bed material at various cross sections are provided. The movable particle sizes for various discharges are computed for a number of cross sections. 2. R&M Consultants, Inc. "Susitna Hydroelectric Project, Reservoir Sedi- mentation," prepared for Acres American Inc., January 1982 (3). 5-1 This report presents estimates of sedimentation in Watana and Devil Canyon Reservoirs. The trap efficiencies of the reservoirs were estimated to vary between 80 and 100 percent. Specific weights of 97, 71.6 and 72.8 pounds per cubic foot (lbs/ft3) were used for the bedload, suspended sediment deposit after 50 years and suspended sediment deposit after 100 years, respectively. The derived sediment rates are given below. The estimated deposit for Devil Canyon with 100 percent trap efficiency of Watana appears to be too low. Watana 100 percent trap efficiency 70 percent trap efficiency 50-year 240,000 af 170,000 af 100-year 472,500 af 334,000 af Devil Canyon with 70 percent trap efficiency of Watana 100 percent trap efficiency 70 percent trap efficiency 79,000 af 55,000 af 155,000 af 109,000 af Devil Canyon with 100 percent trap efficiency of Watana 100 percent trap efficiency 70 percent trap efficiency 8,600 af 6,100 af 16,800 af Turbidity of water released from the reservoirs also is discussed based on data collected by the USGS in 1974-76 and by R&M in 1980-81. It is concluded that the turbidity during the summer months will sharply decrease due to sediment trapping characteristics of the reservoirs. The turbidity during the winter months will be near natural conditions as suspended sedi- ment in near-surface waters will rapidly settle once the reservoir ice cover forms and essentially quiescent conditions occur. 3. Peratovick, Nottingham & Drage, Inc. "Susitna Reservoir Sedimentation and Water Clarity Study," prepared for Acres American Inc., November 1982 (4). This report presents the analysis of turbidity levels in Watana Reservoir. A computer model "DEPOSITS" was used to compute the turbidity at various 5-2 levels in the reservoir., The major conclusions of the report are given below: a. It is likely that sediment particles less than 3 to 4 microns will remain in suspension. This constitutes up to 20 percent of the summer sediment input. Maximum turbidity levels at the outlet are on the order of 50 NTU's, which corresponds to a sediment concentration of 200 to 400 milligram per litre (mg/1). Minimum turbidity levels will be in the order of 10 NTU's. This corresponds to a sediment concentration of 30 to 70 mg/1. b. Turbidity levels at the reservoir outlet during each lllOnth appear to be primarily dependent upon the travel time for sediment slugs, delivered to the reservoir during previous summers, to reach the reservoir out- c. let. Longitudinal mixing, primarily induced by wind turbulence, will tend to mask the near surface sediment slugs. Quantification of longi- tudinal mixing has not been directly addressed within the scope of this task. Wind mixing is significant in retaining sediments of less than about 12 microns in suspension for the upper 50-foot layer of water. d. Reintrainment of sediment from the shallow depth along the reservoir periphery during severe storms will result in short-term high turbidity levels. This will be particularly evident during the summer refilling process when water levels will rise, resubmerging sediment deposited along the shoreline during the winter. e. In spite of some limitations, the data gathered from outside sources supports the conclusion that Watana reservoir turbidity levels will be in the range of 10-50 NTU's. f. Preliminary results from the Eklutna Lake study show summer turbidity levels in the near surface layers to be in the range of '20-40 NTU's. 5-3 This generally agress with the range of turbidity values predicted for the Watana reservoir. 4. R&M Consultants, Inc., "Susitna Hydroelectric Project, Tributary Sta- bility Analysis," prepared for Acres American Inc., December 1982 (5). This report presents field data collected in various tributaries. It also provides a discussion of potential project impact on channel stability near the mouth of tributaries. Nineteen tributaries are selected for the study. Three creeks (Jack Long, Sherman and Deadhorse) are estimated to aggrade and to likely restrict the access by fishes. The tributaries at river miles 127.3 and 110.1, and Skull Creek are estimated to degrade and to affect the railroad bridges. The other tributaries will either degrade or aggrade but without effects on fish access or railroad. 5. Trihey, E. Woody, "Preliminary Assessment of Access by Spawning Salmon into Portage Creek and Indian River," prepared for Alaska Power Au- thority March 1983 (6). This report is based on field data collected during the summer and fall of 1982 by 1~F&G Su-Hydro Aquatic Studies Group and R&M. Entrance conditions at the mouths of Portage Creek and Indian River are cal- culated for mainstem discharges of 8,000 13,400, 21,500 and 34,500 cfs at the Gold Creek gaging station. Average monthly with-project streamflow at Gold Creek are estimated to be in the range of 7,000 to 11,000 cfs. A controlled flow of 12,000 cfs is as- sumed from mid-August to mid-September. The analysis indicates that fish access to Portage Creek and the Indian River has not been a problem and is unlikely to be a problem under with- project conditions. These creeks will adjust streambed gradient and will re-establish entrace conditions. 5-4" 6.0 DATA SOURCES 6. 1 STREAMFLOW Streaflow records collected by the USGS for the Susitna River near Cantwell, at Gold Greek and at Sunshine; for the Chulitna River near Talkeetna; and for the Talkeetna River near Talkeetna were used in this study. The periods of record available are shown below. The stream gaging stations are shown on Exhibit 1. STREAM GAGING STATIONS PERIOD OF RECORD USGS __§aging Station Gage No. Susitna River 15291500 near Cantwell at Gold Creek 15292000 at Sunshine 15292780 Chul:itna River near 15292400 Talkeetna Talk1eetna River near Talkeetna 15292700 6.2 RIVER CROSS SECTIONS Drainage Area, sq mi 4,140 6,160 11,100 2,570 2,006 Period of Record May 1961 -Sep 1972 May 1980 -Present Aug 1949 -Present May 1981 Present Feb 1958 -Sep 1972 May 1980 -Present Oct 1974 -Present Cross sections of the Susitna River have been surveyed at 99 locations be- tween river mile 94.6 near Talkeenta and river mile 150.2, about 1.3 mile upstream from the confluence with Portage Creek ( 7, 8). Cross sections at 23 locations also are available between river mile 162.1 at Devil Creek and river mil,e 186.8 at Deadman Creek ( 9). 6-1~ 6.3 BEDLOAD AND BED MATERIAL Bedload dllscharge data have been collected by the USGS in the Susitna, Chu- litna, and Talkeetna rivers starting in 1981 as shown below. Station Susitna River at at Gold Creek near Talkeetna at Sunshine Chulitna River near Talkeetna BEDLOAD DISCHARGE DATA SUSITNA RIVER BASIN USGS Gage No. Period of Record 15292000 ·Jul-Sep 1981 15292100 Jun -Sep 1982 15292780 Jul -Sep .1981 Jun -Sep 1982 15292400 Jul -Sep 1981 Jun -Sep 1982 No. of Samples 3 15 3 15 3 15 Talkeetna River near 15292700 Jul -Sep 1981 3 Talkeetna Jun -Sep 1982 15 Additional measurements of bedload discharge have been made by the USGS in 191:)3 at the last four stations listed in the above table but were not avail- able for this study. Harza-Ebasco collected 17 bed material samples from the mainstem of the Susitna R:iver and 2 samples from the Chulitna River. Additional 29 samples were collected in the side channels of the Susitna River upstream from the confluenc•~ with the Chulitna River. Size distributions of these samples were determined by sieve a?alysis. Exhibit 3 shows the locations at which the samples .. were taken. Bed material size distributions for the Susitna River also have been estimated by R&M (5) using grid sampling techniques at 38 locations between cross section 4 at river mile 99.58 and cross section 59 at river mile 144.83. Bed material size distributions at the mouths of 6-2 11 tributaries also have been estimated by R&M using the same method. These tributaries join the Susitna River between river mile 113.6 at Lane Creek and river mile 148.9 at Portage Creek. 6.4 SUSPENDED SEDIMENT Susp,ended sediment data are available from the USGS at five sampling stations as listed below. Station Susitna River m!ar Cantwell at Gold Creek at Sunshine Chulitna River Talkeetna Talkeetna River Talkeetna SUSPENDED SEDIMENT DISCHARG& DATA SUSITNA RIVER BASIN USGS No. of Period of Record Gage No. Samples water year 15291500 43 1962-B72, 1982 15292000 370 1949, 1951-1958, 1962, 1967-1968, 1974-1982 15292780 32 1971, 1977, 1981- 1982 near 15292400 51 1958-1959, 1967- 1972,1980-1982 near 15292700 116 1966-1982 6-3 7.0 RESERVOIR SEDIMENTATION 7 • 1 GENERAL APPROACH Suspended sediment loads at the Watana and Devil Canyon dam sites were esti- mated by interpolating the loads at the Cantwell and Gold Creek gages on the Susitna E~ver. Sediment trap efficiencies of the reservoirs were estimated by the Brune's and Churchill's curves. Se:_diment deposits in Devil Canyon Reservoir were estimated for with-and without-Watana Reservoir conditions. Bedloads were estimated as percentages of suspended sediment loads using available~ data at the Gold Creek, Talkeetna, and Sunshine gages on the Susitna River. All bedloads were assumed to be trapped by the reservoirs. Bedloads at Devil Canyon Reservoir were computed for with-and without- Watana Reservoir conditions. 7.2 SEDIMENT LOAD Sediment discharges at the Cantwell and Gold Creek gages were computed by the sediment rating-flow duration curves method. Suspended sediment dis- charges and the corresponding water discharges for the Cantwell gage are shown on Exhibit 4. The data points were grouped into three groups each corresponding to the period from June to October, November to April, and May. Only one sample was available for the November-April period and two samples for the May period. These data are insufficient to develop separate curves. Therefore, one sediment rating curve was fitted visually to all data points. A flow-duration curve for the Cantwell gage is shown on Exhibit 5. The curve is based on 13 years (1962-1972, and 1981-1982) of available daily flow data. 7-1 Using thEl suspended sediment rating curve on Exhibit 4 and the flow-duration curve on Exhibit 5, the mean annual suspended sediment discharge at the Cantwell gage was computed to be about 5,660,000 tons/yr. Suspended sediment discharges and the corresponding water discharges for the Gold Creek gage are shown on Exhibit 6. The samples, collected in the period from 1949 to 1982, were divided into three groups correspnding to June-October, November-April, and May periods. The points for the June- October and May periods indicated separate trend lines and were fitted with two curvE~S. Limited data points were available for the low flow period of November-·April. These points appeared to be fitting the lower part of the May curve~. Therefore, the May curve was used for the November-April peri- od. The daily flow duration curves for the Gold Creek gage for the June-Ocboter and November-May periods were derived using the 1950-1982 flow data and are shown on Exhibit 5. The mean annual suspended sediment discharge at the Gold Creek gage was computed to be about 7,260,000 tons/yr, using the sedi- ment rating curves on Exhibit 6 and the flow duration curves on Exhibit 5. 7.3 RESERVOIR SEDIMENT INFLOW Suspended-sediment inflows to Watana and Devil Canyon Reservoir were com- puted by transposing sediment discharges at the Cantwell and Gold Creek gages~ whose locations bracket the two reservoirs. Sediment discharges at the two gages were assumed to follow the following exponential relationship (10): 7-2 in which qs = sediment discharge per unit drainage area (unit sediment 1 discharge) at point 1 qs = unit sediment discharge at point 2 2 A1 = drainage area for point 1 A2 = drainage area for point 2 n = exponent Using the unit sediment discharges at the Cantwell and Gold Creek gages, exponent "n" in the above equation was computed to be -0.3 76. Thus, susp- ended-sediment discharge at the Watana damsite was computed to be 6,530,000 tons/yr for the drainage area of 5,180 sq mi. Assuming no Watana Reservoir, the suspended-sediment discharge at the Devil Canyon damsite was computed to be 7,030,000 tons/yr using drainage area of 5, 810 sq mi. Bedload discharge was estimated to be three percent of suspended-sediment discharge based on the following analysis. Bedload and suspended sediment discharges for the Susitna River near Talkeetna were estimated to be 43,400 and 2 ,610,000 tons/yr, respectively, as presented later in this report. Thus, the bedload discharge is about 1.6 percent of suspended sediment discharge. For the Sunshine gage, this per- centage is about 3.2 based on the bedload and suspended sediment discharges of 423,000 and 13,330,000 tons/yr, respectively. A value of 3 percent was used in the analysis. 7. 4 SEDIMENT TRAP EFFICIENCY Sediment trap efficiencies of Watana and Devil Canyon Reservoirs were esti- mated by the Brune's and Churchill's curves (1). The trap efficiency of 7-3 Watana was also estimated by Peratrovich, Nottingham and Drage (4) using a sedimentation model. Similar modeling is not available for Devil Canyon Reservoir. A comparison of the trap efficiencies of Watana and Devil Canyon Reservoirs estimated by the three methods is shown in the following table. COMPARISON OF TRAP EFFICIENCIES ESTIMATED BY BRUNE'S CURVES, CHURCHILL'S CURVE, AND SEDIMENTATION HODEL Method Brune's Curves Coarse Sediment Median Curve Fine Sediment Churchill's Curve Local Silt Fine Silt DEPOSITS Hodel Quiescent Minimum Mixing Maximum Mixing Tra:e Watana 100 99 96 100 94 to 96* 86 to 93* 78 to 9ll* Efficiencx, % Devil Canxon 98 94 86 95 88 * Corresponding to dead storage volumes from 5, 340,000 acre-feet to 900,.000 acre-feet (reservoir capacity = 9,470,000 acre-feet at normal maximum pool). The Watana trap efficiency ranges from 96 to 100 percent based on the Brune's curves. The trap efficiency is about 100 percent based on the Churchill's curve for local silt. The trap efficiency computed by a re- servoir sedimentation model, DEPOSITS, ranges from 78 to 96 percent de- pending on reservoir mixing and dead storage volume. The trap efficiency of Devil Canxon Reservoir ranges from 86 to 98 percent based on the Brune's curves. The trap efficiency estimated with the 7-4 Churchill's curves is 95 percent for lbcal silt and 8!:S percent for fine silt, the latter case being for sediment discharged from an upstream reser- voir. Table 2 and 3 show the estimation of the trap efficiencies by the Brune's curve and the churchill's curve. 7.5 SED~~NT DEPOSIT Based on the estimated trap efficiences shown in the above table, Watana Reservoir was assumed conservatively to trap all sediment inflow to the reservoir., The resulting sediment deposits over a 50-and 100-year period will be about 210,000 and 410,000 af. The gross reservoir volume is about 9, 4 70,000 af at a normal maximum pool elevation of 2, 185 ft, of which 5,730,000 af is the dead storage (11). The 100-year sediment deposit is only about 7 percent of the dead storage volume. Without W<:ttana Reservoir, the ·50-and 100-year sediment deposits in Devil Canyon Re:servoir would be about 226,000 and 442,000 af respectively also assuming a trap efficiency of 100 percent. The gross reservoir volume of Devil Canyon Reservoir is about 1, 090,000 af at a normal maximum pool elevation of 1, 455 ft, of which about 7 40,000 af is the dead storage. The 100-year s,ediment deposit is about 60 percent of the dead storage volume. With Watana Reservoir, the 50-and 100-year sediment deposits in Devil Canyon Res:ervoir would be about 16,100 and 31,400 af respectively or about 2 and 4 percent respectively of the dead storage volume assuming 100 percent trap effic:iency for sediments from the intervening drainage area. Any fine suspended sediment passed through Watana Reservoir was assumed to also pass through De~vil Canyon Reservoir. The sedimemt volumes presented above were computed using the procedures of the U.S. Bureau of Reclamation ( 1). Percentages of clay, silt, and sand of 7-5 the incoming suspended sediment were estimated to be 20, 38, and 42, respec- tively, using sediment data for the Cantwe~l and Gold Crek gages. Using the unit weights of clay, silt and sand as 26, 70, and 97 lb/ft3, respectively, the unit weights of the suspended sediment deposit after 50 and llJO years were estimated to be about 80 and 82 lbs/ ft3, respectively. The unit weight of bedload was estimated to be 120 lb/ft3. 7.6 TURBIDITY Since the studies made by R&M {3) and Peratrovich, Nottingham & Drage, Inc. {4), no additional data have been collected on turbidity in the Susitna River. These studies were reviewed as discussed under the section entitled "Review of Previous Studies". The conclusion arrived in these studies were accepted as being reasonable and appropriate to estimate the turbidity of the reservoirs and their outflows. 7-6 8.0 DOWNSTREAM AGGRADATION AND DEGRADATION The operation of the Susitna Project will reduce flood flows and consequent- ly sedime:nt transport capacities of the river downstream from the dams. However, most of the suspended sediments and all bedloads from upstream will be trapped in the reservoirs. The combined effects on the river downstream from the dams would be aggradation in some river reaches and degradaLion in other reaches. available data. A preliminary assessment of these effects were made using 8. 1 GENERAL APPROACH The chann,el aggradation and degradation study covers the Susitna River from its confluence with Portage Creek to the Sunshine gage. This river segment was divided into two reaches -the Middle and Lower reaches-for analysis. Because of the difference in the nature of the problem and data availability for the two reaches, different study approaches were used. The Middle reach runs from the confluence with Portage Creek to the con- fluence with the Chulitna River. The Lower reach runs from the confluence with the Chulitna River to the Sunshine gage. The Middle reach was further divided i.nto 12 subreaches, as shown in Table 1 and Exhibit 7. The sub- reaches wrere selected such that, in general, a major tributary is located near its upstream end. Also, each subreach was sufficiently short such that the average flow depth, velocity, and slope in the subreach would be repre- sentative throughout the entire subreach. River beds below a dam often degrade if the reservoir traps a large portion of the sediment and release clear water which is capable of picking up bed materials. Under such conditions, smaller particles in the riverbed down- stream of the dam are picked up and transported further downstream by river flow. Large particles, however, will remain on the river bed and gradually form an armoring layer, which will stop further degradation. 8-1 The degradation computation for each subreach was based on assumption that bedload irttlow to the subreach is carried through and no deposition occurs. When there~ is a tributary entering the subreach, its bedload is also assumed to be carried through although local and some downstream deposition of the tributaries bedload can be expected under actual conditions. Therefore, the computed dlegradation represents a conservative estimate. The larger particles brought to the mainstream by a tributary may be too large for the mainstem to transport under withm project conditions. The likelihoodl that a part of the tributary bedload may accumulate near its mouth was evaluated by comparing the armoring size in the mainstem under with-project conditions with the size of bed materials near the tributary mouth. Project ef'fects on sediment transport in the Lower reach was evaluated based on a sediment balance analysis. The bedload discharge data at four stream gaging stations: the Susitna River near Talkeetna and at Sunshine, the Chulitna River near Talkeetna and the Talkeetna River near Talkeetna, were used in the analysis. 8.2 MIDDLE REACH 8.2.1 Dondnant Discharge The dominant discharge is defined as the discharge which, if allowed to flow constantly, would have the same overall channel shaping effect as the na- tural fluetuating discharges would (1). The dominant discharge used in com- puting channel degradation or aggradation is usually considered to be either the bankfall discharge or the mean annual flood. The mean annual flood for the Susitna River at Gold Creek was estimated to be 52,000 cfs under natural conditions and 13,400 cfs under with-project conditions ( 5). The mean annual flood for natural conditions increases 8-2 from 51,100 cfs in subreach 1 to 53,600 cfs in subreach 12. The mean annual flood for with-project conditions increases from 12,500 cfs in subreach 1 to 15,000 cfs in subreach 12. 8.2.2 Bed Material Bed materials of the Susitna River consist roostly of gravel and cobble with a small percentage of sand. Size distribution of the bed materials have been analyzed by Harza-Ebasco, R&M, and the USGS. Harza-Ebasco collected and analyzed 46 bed material samples from the mainstem and side channels of the Susitna River. Of these samples 40 are from the Middle reach. Samples from under water were collected either with a pipe dredge of six-inch dia- meter in the middle of the river or with a shovel near the banks where water depth was~ about 1 to 1.5 feet. Samples from gravel bars in the river and berms near the head of the sloughs were collected by a shovel. distributions of all samples were determined by sieving. The size The samples collected by Harza-Ebasco from under water are considered reasonably representative of bed material subject to transport. The median diameters of the samples collated in the mainstream are generally larger than those of the samples collected in the side channels (Table 4). R&M ( 5) determined the size distrubution of bed material by the grid-by- number me~thod at 38 locations in the Middle reach between cross sections 4 and 59. Most samples were taken near the river banks. Comparing to the samples collected from the channel, the particle sizes of bed material col- lected near the banks are generally larger. The USGS collected bed material samples at two gaging stations in the Middle reach: the Susitna River at· Gold Creek and near Talkeetna. The samples were collected by the pipe dredge of six-inch diameter. 8-3 • In some of the subreaches more than one sample were available while in other either only one or no samples were collect~d. Because of the limited number of the samples the bed material data used in the degradation computation were judiciously selected from all available bed material data. The size distribution used for each subreach is shown on Exhibit 8. Some size dis- tribution are the average of two or more samples. 8.2.3 Tributaries and Sloughs The Middle reach has 19 major tributaries. The two largest tributaries are Portage Creek in Subreach 1 and the Indian River in Subreach 3, with a drainage area of about 176 sq mi and about 82 sq mi, respectively. The mean annual flood is estimated to be 1680 cfs for Portage Creek and 786 cfs for Indian River (5). The other tributaries have drainage areas ranging from 24 sq mi to 0.4 sq mi. The mean annual floods are estimated to range from 260 cfs to 4 cfs (5). Table 5 lists drainage areas, mean annual floods and bed material sizes of the tributaries. Sloughs are side channels which are not hydraulically connected with the Susitna River flow until the berms at the upstream end of the sloughs are overtopped. A slough, when its berm is not overtopped, usually carries a small flow ( 3 to 20 cfs) from its drainage area or seepage. Some of the sloughs are identified on Exhibit 7. 8.2.4 Degradation Limited by Armoring Degradation limited by armoring in each subreach was computed using the procedures in "Design of Small Dams" (1). The armoring particle size was estimated for the with-project dominant discharge by four methods: com- petent bottom velocity, critical tractive force, Meyer-Peter and Muller formula, and the Schoklitsch formula. The average of the four armoring sizes computed is taken as the armoring size in the subreach, as listed in Table 1. The flow velocity, depth, bed slope, channel width, and roughness 8-4 coefficient used were obtained from a hydraulic study made by Harza-Ebasco (12). The armoring sizes under natural conditions also were computed, using the dominant discharges under natural conditions, and are listed in Table 1 for comparison. The depth of with-project degradation required to form an armor layer was then computed using the armoring size and bed material size distribution described earlier. The bed material size distributions are summarized in Table 1 by their D16, Dso, and Dgo sizes, which, respectively, are the sizes at which 16, SO and 90 percent (by weight) of the bed material particles are finer. Table 1 shows that the with-project armoring size ranges from 40 mm in sub- reach 1 to 21 mm in subreach 12. The size generally decreases in downstream direction. The estimated degradation ranges from zero to 0.3 ft. The de- gradation for each subreach was computed by assuming no bedload inflow. 8.2.5 Aggradation Near Tributary Mouths The transportable size under natural conditions is considerably greater than Dso of bed material for all tributaries as shown in Table 1. Thus most bedload inflow from these tributaries are transported downstream by the mainstem flow. This indicates that long-term accumulation at tributary mouths is not likely to occur under natural conditions. The transportable size of the Susitna River under with-project condition is either smaller or only slightly greater than Dso of bed material at the mouth of a tributary depending on the tributary (Table 1). Thus, part of bedload carried down by some tributaries may accumulate at the mouth of the tributaries and in the mainstem immediately downstream from the tributary. This will tend to compensate the minor degradation discussed in the previous section. Further analyses will be carried out to estimate quantitatively the magnitude of aggradation near the mouths of these tributaries based on 8-5 field investigations being made by USGS (1983-84) program on the Indian River and Portage Creek. Bed material data for some of the tributaries listed in Table 1 are not available. Assuming that their bed materials are similar to those of nearby tributaries, a similar conclusion would be reached. 8.2.6 Other Project Effects During a field reconnaissance in August, 1983, a sample of bed material was taken on the berm of Slough 21. This sample is believed to be fairly re- presentative of bed material on most of the berms. The Dso of this sample is smaller than the armoring size corresponding to natural conditions (Table 1). Thus, under the present condition, erosions periodically occur on the berms. Field reconnaissances made during high and low flows indicate that deposition of sediment (fine sand, silt and clay) occurs in the slough during low flows, which is flushed out during high flows. Under with-project conditions, the armoring size is smaller than the Dso• Thus, erosion of the berms would be much less under normal condition. Some aggradation near the berms could be expected because the main river channel would become more confined and any occassional higher flows would push the moving bedload near the entrance of sloughs. This would tend to close the entrance to the sloughs and there will be less frequent overtopping of the berms by the mainstem flows to flush out the fine sediment deposits in the sloughs. 8.3 LOWER REACH The effect of the project on the river below the Chulitna-Susitna River confluence was evaluated by accounting total sediment inflow and outflow for the Lower reach. 8-6 8.3.1 Cross Sections Exhibits 9 and 10 show two typical cross sections (Sections 1 and 2, Exhibit 7) of the Susitna River in the Lower reach. Exhibits 11 and 12 show the cross sections of the Susitna River near Talkeetna and Sunshine gages. Exhibit 13 shows Susitna River section at the upstream face of the Sunshine bridge and Exhibits 14 and 15 show the cross sections of the Chulitna River and Talkeetna River at the sediment measuring stations. All of the cross- sections were surveyed more than once during the period from 1980 to 1982 except those shown on Exhibit 13 which were surveyed in 1971. The cross sections indicate a fairly large seasonal aggradation or degradation. Exhi- bit 13 shows that scouring occurs in spring and summer during the high flow season, but deposition occurs in the fall during the low flow season. The continuous changes in the cross sections (Exhibits 9 to 15) indicate that aggradation and degradation have occurred continuously in the Lower reach. However, results of field reconnaissances did not show any evidence of large long-term aggradation or degradation in the reach. Therefore, the reach can be assumed to be in equibrium under natural conditions on a long- term basis. 8.3.2 Bedload Discharge Rating Curves Bedload discharges measured by the USGS at two stations on the Susitna River near Talkeetna and at Sunshine and at two stations on the Chulitna and Talkeetna Rivers in 1981 and 1982 were used in this study. Additional bed- load discharge measurements at these four stations have been made by the USGS in the summer of 1983. However, the results of these measurements were not available for the present study. Bedload discharges for the Susitna River near Talkeetna and at Sunshine, for the Chulitna River near Talkee~a, and for the Talkeetna River near Talkeetna are presented in Tables 6 through 9. These were plotted, and a curve was fitted individually to the data points for the Susitna River near 8-7 Talkeetna (Exhibit 16), the Talkeetna River near Talkeetna (Exhibit 17) and the Susitna River at Sunshine (Exhibit 18). The data points for the Chulitna River near Talkeetna indicated a wide scatter (Exhibit 19) and fitting of a curve to these points was considered inappropriate. The Chulitna data was carefully reviewed along with the daily discharges during the periods when the samples were taken. It was noticed that the early June flows bring heavy bedload which decreases with time. At that time, even higher flows transport relatively small amount of bedload. However, abrupt increase in bedload was noticed in the subsequent months because of slight increase in flows (see Table 7). Once this increase had occurred, the subsequent higher flows transported smaller amount. This indicates that the bedload transport in the river depends upon supply of coarse material from sources (such as upstream glaciers and bank erosion) other than river bed erosion caused by high flows. To provide some estimate of annual bedload transport, the Chulitna data were grouped respectively for the months of June, July and August-September for deriving the bedload discharge rating curves. This provided somewhat less scatter of the data for each period as shown on Exhibit 19. A preliminary analysis was also made to develop a correlation between bed- load and suspended sand transport for the Chulitna River. The analysis was made based on the assumption that coarse sand and very fine gravel moving as bedload during medium flows could become a part of suspended load during high flows. Because of limited number of data poin~s, a well defined rela- tionship was not discernable. As theoretically such a relationship is pos- sible, the data will be re-analyzed when results of 1983 and 1984 sampling become available. 8-8 8.3.3 Suspended Sediment Discharge Rating Curves These curves were developed for the Susitna River near Talkeetna and at Sunshine, the Chulitna River near Talkeetna and the Talkeetna River near Talkeetna based on suspended sediment samples taken in 1982 and also in the preceeding years. The curves are sham on Exhibits 20 through 23. The period of record also is shown on each exhibit. 8.3.4 Particle Size of Bedload Size distributions of particles contained in each bedload sample are shown in Tables 6 through 9 for the four stations. These data were reviewed and it was noticed that the Susitna River near Talkeetna and the Talkeetna River near Talkeetna carry coarser material in June compared to that carried in July and August (Exhibits 24 and 26). This is probably due to availability of coarser material during early flood sea- son and after breakup of ice. This also can be seen from Tables 6 and 8, which indicate lower bedload discharges in July and August compared to those in June for the same water discharges. The samples taken at the Talkeetna River near Talkeetna and the Susitna River at Sunshine in September after the flood of September 15, 1982, also indicate coarser material (Exhibits 24 and 27). Average size distribution of bedload material for the Chulitna River and the Susitna River at Sunshine are sharin on Exhibits 25 and 27. The Chulitna River does not show large variation in bedload sizes for different months. The Susitna River at Sunshine shows nearly the same characteristics as for the Susitna River near Talkeetna and Talkeetna River near Talkeetna. 8-9 Particle sizes also can be divided into three categories: Sand (0.064 mm to 2.0 mm), Gravel (2.0 mm to 64.0 mm), and Cobble (64.0 mm to 256.0 mm). Average percentages of sand, gravel, and cobble based on all bedload samples collected at the four stations are summarized below. Gage Susitna River near Talkeetna Chulitna River near Talkeetna Talkeetna River near Talkeetna Susitna River at Sunshine Size Distribution of Bedload Particles, % Sand Gravel Cobble 78 41 75 56 16 58 23 42 6 1 2 2 Bedload for the Susitna River near Talkeetna contains 78 percent of sand, 22 percent of gravel and cobble. The Chulitna bedload contains a lower frac- tion (41 percent) of sand and a higher fraction (59 percent) of gravel and cobble. The Talkeetna River bedload size distribution is similar to that of the Susitna River near Talkeetna, with 75 percent sand and 25 percent gravel and cobble. The Size distribution of bedload for the Susitna River at Sun- shine is about 56 percent sand and 44 percent gravel and cobble. 8.3.5 Bed Material The size distributions of bed material at the four bedload stations also have been analyzed by the USGS. The resulting size distributions are listed in Tables 10 through 13. The samples were taken at different verticals across the sampling section. The average percentages of sand," gravel, and cobble for each station are as follows: 8-10 Gage Susitna River near Talkeetna Chulitna River near Talkeetna Talkeetna River near Talkeetna Susitna River at Sunshine Size Distribution of Bed .l-1aterial Particles % Sand Gravel Cobble 0 26 5 5 30 64 52 66 70 10 43 29 8.3.6 Balance of Total Sediment Inflow and Outflow For the water year 1982, the total sediment inflow in the study reach was taken as the sum· of total loads measured on the Susitna, Chulitna, and Talkeetna Rivers above their confluence. The total sediment outflow from the reach was taken as the load measured at the Susitna River at Sunshine. The total load is the sum of bedload and suspended sediment discharges. The annual bedloads and suspended sediment discharge were computed by the sedi- ment rating -flow duration curves method. The sediment rating curves for the four gages are shown in Exhibits 16 through 23. The 1982 flow duration curves were developed from provisional daily flow data obtained from the USGS for the Susitna River at Sunshine, and the Talkeetna River near Talkeetna. The seasonal flow duration curves were developed for the Chulitna River near Talkeetna. Because no daily flow data are available for the Susitna River near Talkeetna, a flow duration curve for the Susitna River at Gold Creek gage was developed. For each duration point, the discharge near Talkeetna was estimated to be 103 percent of the corresponding discharge at Gold Creek, based on the drainage area ratio. Exhibits 28 and 29 show the daily flow duration curves for 1982. Using the bedload discharge rating curve and the corresponding flow duration curve, the bedload discharge for the Susitna River near Talkeetna was com- puted to be about 43,400 tons for 19d2. Similarly, the bedload discharges for the Chulitna River near Talkeetna and Talkeetna River near Talkeetna were calculated to be 1,220,000 and 197,000 tons respectively for 1982. The 8-11 corresponding suspended sediment discharges are 2,610,000, 7,410,000 and 1,640,000 tons, respectively. Thus, the total sediment inflow to the Lower reach is about 13,120,000 tons. It may be pointed out that the 1982 suspended sediment discharge for the Susitna River near Talkeetna estimated to be 2,610,000 tons is considerably less than the estimated mean annual suspended sediment discharge of 7,260,000 tons/yr at Gold Creek. This difference is likely because of the following reasons: 1. Sediment transport in the Susitna River varies significantly from year to year. The 1982 could be a year of low sediment trans- port. 2. During 1982, there could have been unusually large sediment deposition between Gold Creek and Talkeetna; 3. Sediment transport in the Susitna River varies considerably from year to year and season to season. The mean annual suspended sediment discharge of 7,260,000 tons estimated for Gold Creek may be biased due to the utilization of a single sediment rating curve. A better procedure would be to develop a series of annual or seasonal curves and compute sediment discharge for each year or season. This method will be very time consuming and was not used in this study. The bedload discharge for the Susitna River at Sunshine was computed to be 423,000 tons for the same year. The suspended sediment discharge was 13,330,000 tons. Thus, the total sediment discharge is 13,753,000 tons compared to the total inflow of 13,120,000 tons to the reach as estimated above based on the data at the three gaging stations located above the confluence. This indicates that about 633,000 tons of total sediment were contributed from the reach between the three upstream gages and the Sunshine . 8-12 gage. This contribution appears to be somewhat higher probably because of some inaccuracy in the estimation of sediment discharges at the gaging stations. 8.3. 7 Project Effect Under with-project conditions, the total sediment discharge passing through the confluence will not be significantly less than that under natural condi- tions because the Chulitna and Talkeetna rivers which currently contribute a major portion (about 80 percent) of the total sediment load, will not be affected by the project. However, the total sediment discharge that can be carried by the Susitna River near Sunshine will be greatly reduced due to the attentuation of floods by the reservoirs. This indicates that aggrada- tion is likely to occur below the confluence of the Susitna River with Chulitna and Talkeetna. Daily flow duration curves for with-project conditions are not yet avail- able. Therefore, the effect of the project on bedload discharge passing the Sunshine gage was computed with the monthly flow duration curves presented in the License Application Exhibit E, Figure 3.2. 161 for Watana operation (13). The computation shows that the mean annual bedload discharge would be a bout 252,000 tons/yr and the suspended sediment discharge would be about 7,380,000 tons/yr under with-project conditions. This sediment discharge capacity is considerably smaller than that under natural conditions as indi- cated by the total load of 13,753,000 tons estimated for water year 1982. Therefore, long term aggradation is likely to occur and the aggradation will start at the mouth of the Chulitna River. It is likely that the existing delta of the Chulitna River will extend toward the left bank of the Susitna River. The extension of the delta formation, however, is unlikely to cause severe problem on flows in the Susitna River because much more stable flows under with-project conditions will eventually develop a river channel which is better defined than under natural conditions. 8-13 REFERENCES REFERENCES 1. u.s. Bureau of Reclamation, "Design of Small Dams," 2nd ed., Denver~ Colorado, 1977. 2. R&M Consultant, Incorporated, "Susitna Hydroelectric Project, River Morphology," prepared for Acres American Incorporated, Jan. 1982. 3. R&M Consultants Incorporated, "Susitna Hydroelectric Project, Reservoir Sedimentation," prepared for Acres American Inc; for Alaska Power Au- thority, 1982. 4. Peratrovich, Nottingham and Drage, Inc., "Susitna Reservoir Sedimenta- tion and Water Clarity Study," prepared for Acres American Inc., 1982. 5. R&M Consultants Incorporated, "Susitna Hydroelectric Project, Tributary Stability Analysis," prepared for Acres American Inc; for Alaska Power Authori.ty, Dec. 1982. 6. Trihey, E.W., "Preliminary Assessment of Access by Spawning Salmon to Side Slough Habitat Above Talkeetna," prepared for Acres American Inc; 1981. 7. R&M Consultant Incorporated, "Susitna Hydroelectric Project, Hydro- graphic Surveys Closeout Report, .. Final Draft, prepared for Acres Ame- rican Inc; for Alaska Power Authority, Oct. 1981. 8. R&M Consultants Incorporated, "Susitna Hydroelectric Project, 1982 Hy- drographic Survey Report," prepared for Acres American Inc; for Alaska Authority. 1982 9. R&M Consultants Incorporated, "Susitna Hydroelectric Project, Hydraulic and Ice Studies," prepared for Acres American Inc; for Alaska Power Authority, Mar. 1982. 10. Vanoni, V.A., Editor, "Sedimentation Engineering, Chapter IV." ASCE Manuals and Reports on Engineering Practice -No. 54, 1975. 11. Acres American Inc., "Application for License for Major Project Susitna Hydroelectric Project," Exhibit F, "Supporting Design Report (Prelimi- nary)," prepared for Alaska Power Authority, Feb. 1983. -1- REFERENCES {Cont'd) 12. Harza-Ebasco Susitna Joint Venture, "Susitna Hydroelectric Project, Water Surface Profiles and Discharge Rating Curves for Middle and Lower Susitna River," Dec. 1983. 13. Acres American Inc., "Application for License for Major Project Susitna Hydroelectric Project," Vol. SA, Exhibit E, Chapter 2, "Water Use and Quality," prepared for Alaska Power Authority, Feb. 1983. -2- TABLES Table 1 RIVER BED DEGRADATION, ARMORING SIZE AND BED MATERIAL SIZE Armoring Size, mm Post-Project Bed Material Size, mm Cross Pre-Post-Degradation, Mainstem Tributar;y: or Slough Reach Section Project Project ft Ql6. _l5n. Q9fl. Creek or Slough Qu_ ~ ~ 1 62-57 120 40 o.o 63 70 79 Portage Creek 14 33 100 Jack Long Creek Slough 22 2 57-51 87 36 o.o 63 70 79 Slough 21 7 40 96 Slough 20 3 51-45 95 46 0.2 39 62 82 lndian River 33 50 86 Gold Creek 17 36 94 RM 132.0 Creek 4 45-36 73 35 0.2 23 51 83 4th of July Creek 14 25 54 5 36-32 51 28 0.3 10 37 97 Sherman Creek 16 30 70 6 32-30 51 25 o.o 28 49 95 Slough 9 RM 128.5 Creek 7 30-26 61 28 0.2 13 31 80 RM 127.3 Creek Skull Creek 10 20 47 Slough 8 RN 123.9 Creek 8 26-24.1 53 27 0.2 12 37 75 RM 121.0 Creek 7 20 65 .Deadhorse Creek 8 19 55 9 24.1-19 58 30 0.1 21 45 110 Little Portage 13 26 63 HcKenzie Creek 9 18 45 10 19-18 52 23 0.2 5 36 118 Lane Creek 5 13 47 Lane Slough 11 18-7 57 26 0.1 21 44 70 Gash Creek RJvi 110.0 Creek 12 7-3 30 21 0.1 17 40 68 Whiskers Creek Table 2 RESERVOIR TRAP EFFICIENCY BY BRUNE'S CURVES Reservoir Storage Capacity af Average Annual Inflow af Capacity -:-Inflow Trap Efficiency Max. Median Min. Watana Devil Canyon 9,47o,ooull5,7so,oool/ 1.64 1,090,00ufl6,580,00o6/ 0.17 100 99 98 94 1J At normal maximum pool elevaton 2185 feet above mean sea lev'el. From License Application, Exhibit E, Chapter 2, page E-2-55 (11). 1/ At normal maximum pool elevation 1455 feet above mean sea level. From License Application, Exhibit E, Chapter 2, page E-2-55 (11). 96 86 1/ Converted from average annual flow of 7990 cfs at Watana, as shown in License Application, Exhibit E, Chapter 2, Table E.2.4 (11). !±/ Converted from average annual flow of 9080 cfs, as shown in Lic:ense Application, Exhibit E, Chapter 2, Table E .2.4 ( 11). Table 3 RESERVOIR TRAP EFFICIENCY BY CHURCHILL'S CURVES (1) (2) (3) (4) (5) (6) Average2/ (7) (8) Cross-Retention Storage 1/ AverageY Retentionlf Reservoir!~ Sectional MeanW Period 1" Reservoir Capacity Inflow P-eriod Length Area Velocity Velocity ft3 cfs sec ft £t 2 ft/sec sec2 /ft Watana 4.13xloll 7990 5.17x107 2.75x105 1.50x106 0.53x10-2 9.70x109 Devil Canyon (local silt) 0.48x1o11 9080 0.52xl07 1.69x1o5 0.28x106 3.23x1o-2 o.16x1o9 Devil Canyon (fine silt) At normal maximum pool elevation 2185 ft for Watana and 1455 ft for Devil Canyon. From License Application, Exhibit E, Chapter 2, page E-2-55. From License Application, Exhibit E, Chapter 2, Table E.2.4. Col. (2) 1-Col. (3). (9) % of Silt Passing < 0.1 5 12 Converted from 52 reservoir miles for Watana and 32 reservoir miles for Devil Canyon. Col. (2) 1-Col. (5). Col. (3) 1-Col. (6). (10) Trap Effi- ciency % 100 Y5 88 Table 4 BED MATERIAL SIZE DISTRIBUTION SAMPLES COLLECTED BY HARZA-EBASCO Location 1. LRX-1.0, left channel, left bank 2. LRX-1.0, l,eft channel, center 3. LRX-1.0, left channel, right bank 4. LRX-1.0, right channel, center 5. LRX-2.3, on a bar in the middle of the river 6. LRX-2.3, near left bank 7. LRX-3.3, near left bank 8. LRX-3.3, near right bank 9. LRX-7.0, right channel 10. Near Talkeetna Camp, pavement (bar) 11. Near Talkeetna Camp, sub-pavement (bar) 12. LRX-42, center 14. LRX-45, center 15. LRX-51, center 16. Near LRX-55, on the berm of slough 21 17. LRX-61, centerll 18. Chulitna R:iver above confluence, bar 19. Chulitna River above confluence, sub-pavement 20. LRX-4, East bank, sub-pavement 21. LRX-4, East bank, pavement 22. LRX-4, East bank, large sizes 23. LRX-4, Sit,e 1, sub-pavement 24. LRX-4, Sit,e 1, pavement 25. LRX-4, Site 1, large sizes..V 26. LRX-4, Sit1e 2, sub-pavement 27. LRX-4, Site 2, pavement 28. LRX-4, Sit1e 2, large sizes 29. Near RM 10'9.3, pavement 30. Near RM 10'9.3, sub-pavement 31. Near LRX 1iB.2, Site 1, sub-pavement 32. Near LRX 1B.2, Site 2, sub-pavement 33. Near LRX 18 .• 2, lower end sample 34. Near LRX 18.2, upper end pavement 35. Upstream Lane Creek, pavement 36. Upstream Lane Creek, sub-pavement 37. Near 4th of July Creek, side channel, pavement 38. Near 4th of July Creek, side channel, pavement 39. Near 4th o:f July Creek, side channel, sub-pavement 40. Near slough 10, pavement 41. Near slough 10, sub-pavement 42. Right channel slough 11, sub-pavement 43. Right channel slough 11, pavement 44. Side chann1el downstream slough 11, pavement 45. Side chann,el downstream slough 11', sub-pavement 46. Side chann,el between LRX 46-48, pavement 4 7. Side chann,el between LRX 46-48, sub-pavement 48. Side chann,el between LRX 46-48, large sizes..ll JJ Sample not representative lJ Sizes between 90 and 100 mm 11 Sizes between 100 and 124 mm Date of Sampling 08-25-83 08-25-83 08-25-83 08-25-83 08-25-83 08-25-83 08-25-83 08-25-83 08-25-83 08-26-83 08-26-83 08-25-83 08-25-83 08-25-83 08-25-83 08-25-83 08-26-83 08-26-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 10-06-83 06-23-83 10-06-83 10-06-83 06-22-83 06-22-83 06-22-83 06-24-83 09-27-83 09-27-83 10-06-83 10-06-83 10-06-83 Bed Material Size, MM 0 16 °so 0 9o 0.4 30 54 30 1.7 5 34 37 30 135 26 38 38 63 7 20 1.2 8 2 5 80 1.2 5 1.5 4 38 26 0.4 2.4 2 6 0.4 24 0.6 4.5 7 0.8 0.7 0.7 2 13 2.5 2.5 16 0.8 0.7 70 62 so 20 24 58 64 50 160 45 52 65 70 40 30 15 30 36 30 90 12 30 20 20 70 65 14 50 30 54 10 58 16 30 38 13 20 20 32 60 26 22 50 17 28 76 75 90 62 55 72 88 72 200 72 65 78 78 96 36 54 70 60 70 100 36 70 38 40 95 97 39 130 140 130 50 94 56 80 90 67 70 70 90 110 80 74 90 40 Table 5 TRIBUTARY FLOODS AND BED MATERIAL SIZES Mean.!/ Drainage!/ Annual River Flood, Area, Bed Material Sizel/, mm Tributary Mile cfs sq mi 016 Dso D8~ Portage Creek 148.9 1680 175.6 14 33 78 Jack Long Creek 144.9 181 18.0 Indian River 138.7 786 82.2 33 50 76 Gold Creek 136.7 260 24.1 . 17 36 76 RM 132.0 Creek 132.0 17 1. 48 4th of July Creek 131.2 187 20.8 14 25 45 Sheru1an Creek 130.8 72 6.76 16 30 58 RM 128.5 Creek 128.5 14 1. 03 RM 127.3 Creek 127.3 28 2.11 Skull Creek 124.3 51 4.49 10 20 39 RM 123.9 Creek 123.9 67 6.86 Deadhorse Creek 120.9 51 4.61 8 19 43 RM 121.0 Creek 121.0 16 1. 52 7 20 50 Little Portage Creek 117.8 23 2.45 13 26 51 McKenzie Creek 116.8 21 2.07 9 18 37 Lane Creek 113.6 117 10.0 5 13 35 Gash Creek 111.6 4 0.43 IUVJ. 110.1 Creek 110.1 21 1. 98 Whiskers Creek 101.2 114 15.4 .!1 From R&M, "Tributary Stability Analysis," Tables 4.2 and 4.4. Table 6 BEDLOAD DISCHARGE AND SIZE DISTRIBUTION 15292100 SUSITNA RIVER NEAR TALKEETNA, ALASl<.Alf Water Bedload Discharge, Discharge, % Finer than Indicated Size in Millimeter Date cfs tons/day 0.125 0.25 0.50 1.0 2.0 4.0 8.0 16 32 64 76 -- 6/03/1982 35,800 2840 0 3 37 47 48 49 52 54 58 74 100 6/08/1982 44,400 1500 1 3 53 63 69 71 75 79 86 100 100 6/15/1982 24,200 831 0 0 24 32 32 33 35 38 44 76 100 6/22/1982 37,000 992 0 2 47 58 60 60 61 61 62 64 100 6/30/1982 30,200 442 0 1 33 39 40 41 43 46 84 100 100 7/08/1982 20,800 324 0 0 65 94 96 97 99 99 100 100 100 7/14/1982 30,800 906 0 1 51 71 74 75 77 81 90 100 100 7/21/1982 25,000 360 0 1 65 90 92 93 94 96 100 100 100 7/28/1982 30,800 600 0 1 70 85 86 88 91 93 100 100 100 8/04/1982 22,800 215 0 2 78 98 99 99 99 100 100 100 100 8/10/1982 20,200 282 0 1 66 94 96 96 96 97 100 100 100 8/18/1982 17,800 106 0 1 69 97 99 100 100 100 100 100 100 8/25/1982 16,900 110 0 1 69 97 99 100 100 100 100 100 100 8/31/1982 19,400 188 1 1 73 95 97 97 98 98 100 100 100 9/19/1982 28,900 372 0 2 63 78 80 80 82 84 91 100 100 ----- Average 0.1 1 58 76 78 79 80 82 88 94 100 lJ Source: u.s. Geological Survey Table 7 BEDLOAD DISCHARGE AND SIZE DISTRIBUTION 15292400 CHULITNARIVER NEAR TALKEETNA, ALASKAli Water Bedload Discharge, Discharge, % Finer than Indicated Size in Millimeter Date cfs tons/day 0.25 0.50 1.0 2.0 4.0 8.0 16 32 64 76 -- 7/22/1981 31,900 2,970 2 15 22 26 30 45 70 93 96 100 8/26/1981 22,500 3,870 1 12 19 27 40 56 73 89 97 100 9/29/1981 6,000 2,900 0 15 29 44 55 77 91 99 100 100 6/04/1982 12,500 11,400 1 14 28 35 54 74 90 99 100 100 6/09/1982 17,200 18,300 1 15 38 47 54 67 8l 95 100 100 6/16/1982 14,600 11,400 1 11 40 52 63 74 83 93 100 100 6/22/1982 19,400 10,200 1 28 53 58 64 71 79 91 100 100 6/29/1982 28,900 13,000 2 26 38 45 57 74 87 98 100 100 7/07/1982 20,600 9,610 1 17 47 53 58 68 80 94 100 100 7/13/1982 22,800 9,110 0 11 20 24 34 50 69 88 !:19 100 7/20/1982 23,100 13,800 1 12 35 40 45 57 67 85 100 100 7/27/1982 33,400 6,900 1 15 28 35 42 53 63 84 100 100 8/03/1982 23,500 7,490 1 16 38 46 53 62 75 90 98 100 8/11/1982 21,700 9,670 0 13 30 35 41 51 67 90 100 100 8/17/1982 22,000 12,100 1 12 39 46 54 66 80 93 100 100 8/24/1982 17,900 7,560 1 12 25 29 37 52 70 91 100 100 9/01/1982 17,100 7,480 1 17 40 56 64 75 86 95 100 100 9/18/1982 29,600 2,560 1 22 36 41 45 53 64 82 100 100 ----- Average 0.9 16 34 41 49 62 76 92 99 100 11 Source: u.s. Geological Survey Table U BEDLOAD DISCHARGE AND SIZE DISTRIBUTION 15292700 TALKEETNA RIVER NEAR TALKEETNA, ALAsKAl/ Water Bedload Discharge, Discharge, % Finer than Indicated Size in Millimeter Date cfs tons/day 0.125 0.25 0.50 1.0 2.0 4.0 8.0 16 32 64 76 ---- 7/21/1981 16,800 2340 1 12 46 54 56 57 59 64 78 97 100 8/25/1981 9,900 756 0 5 68 85 87 88 89 100 100 100 100 9/29/1981 2,910 25 0 6 86. 99 100 100 100 100 100 100 100 6/02/1982 19,100 2\:iOO 1 3 35 90 94 96 97 100 100 100 100 6/09/1982 14,000 5790 0 1 12 30 34 36 41 56 85 100 100 6/16/1982 11 '400 1630 0 0 13 31 35 38 41 46 59 86 100 6/23/1982 12,400 1410 0 1 32 60 64 66 71 82 98 100 100 6/29/1982 10,900 620 0 2 44 73 76 77 77 79 83 91 100 7/07/1982 6,840 1080 0 0 39 91 93 93 93 94 96 100 100 7/13/1982 9,020 243 0 18 66 89 91 92 93 95 96 100 100 7/20/1982 8,560 516 0 1 42 64 65 65 65 65 67 100 100 7/28/1982 14,300 885 0 3 52 81 85 88 90 92 95 100 100 8/03/1982 9,140 802 0 2 38 62 64 65 67 69 78 84 100 8/10/1982 7,070 2470 0 1 55 97 98 99 99 99 100 100 100 8/17/1982 6,260 2380 0 1 23 82 93 96 98 99 100 100 100 'd/24/1982 5,960 1800 0 0 14 84 95 97 98 99 100 lOU 100 8/31/1982 9,200 1460 0 1 18 84 92 93 94 95 99 100 100 9/20/1982 14,600 2740 0 1 12 26 27 2'd 33 49 82 100 100 ----- Average 0.1 3 39 71 75 76 78 82 90 98 100 lJ Source: u.s. Geological Survey Table ~ BEDLOAD DISCHARGE AND SIZE DISTRIBUTION 15292780 SUSITNA RIVER AT SUNSHINE, ALASKAlf Water · Bedload Discharge, Discharge, % Finer than Indicated Size in Millimeter Date cfs tons/day 0.062 0.125 0.25 0.50 1.0 2.0 4.0 8.0 16. 32 64 76 -- 7/22/1981 89,000 3,540 0 1 13 42 47 49 54 60 70 85 100 100 8/26/1981 61,900 3,040 0 1 22 76 79 81 83 87 92 98 100 100 9/30/1981 19,100 385 0 0 7 62 70 70 72 73 77 83 100 100 6/03/1982 71,000 6,080 0 0 2 15 22 26 27 30 38 64 100 100 6/10/1982 64,700 13,600 0 0 2 12 17 17 18 20 29 54 96 100 6/17/1982 50,700 1,870 0 0 2 47 65 65 66 66 69 75 100 100 6/21/1982 78,900 2,510 0 1 12 18 50 51 53 57 62 70 95 100 6/28/1982 75,400 6,390 0 0 3 17 22 23 25 27 46 64 100 100 7/06/1982 46,700 6,020 0 0 2 35 46 47 49 57 71 86 100 100 7/12/1982 59,200 3,800 0 0 3 52 75 77 80 85 88 96 100 100 7/19/1982 61,500 3,960 0 0 2 40 54 58 62 69 75 84 87 100 7/26/1982 99,000 8,750 0 0 2 18 28 30 33 39 53 77 97 ·10o 8/02/1982 63,600 3,480 0 0 4 60 73 74 74 75 78 93 97 100 8/09/1982 53,800 5,220 1 1 5 62 81 82 83 85 89 94 100 100 8/16/1982 48,100 2,740 0 0 2 61 83 84 85 86 92 98 100 100 8/23/1982 38,500 1,050 0 0 1 55 85 88 89 90 92 92 100 100 8/30/1982 39,200 1,480 1 2 4 44 63 64 64 65 66 70 100 100 9/17/1982 87,400 8,120 0 0 1 12 20 23 26 37 60 78 100 100 ----- Average 0.1 0.3 5 40 54 56 58 62 69 81 98 100 lf Source: u.s. Geological Survey Table 10 BED MATERIAL SIZE DISTRIBUTION 15292100 SUSITNA RIVER NEAR TALKEETNA, ALASKA1f Water Discharge, % Finer than Indicated Size in Millimeter Date cfs 16 32 64 128 7/28/1982 30,800 0 0 0 100 0 100 100 100 8/04/1982 22,800 0 7 53 100 1 6 42 100 9/19/1982 28,700 0 0 18 100 0 0 0 100 0 4 30 100 0 2 19 100 0 5 100 Average: 0.1 13 30 100 1J Source: U.S. Geological Survey Th.b1e 11 BED MATERIAL SIZE DISTRIBUTION 15292400 CHULITNA RIVER NEAR TALKEETNA, AIASJ<A!_/ W:iter Discharge, % Finer than Indicated Size in Hillimeter Date cfs 0.125 o. 2"> o. 50 1.0 2.0 4.0 8.0 lfi 32 64 128 --- 9/29/1981 6,000 0 7 52 81 94 100 100 0 1 1 2 10 57 92 100 100 100 0 2 10 18 30 59 83 9R 100 100 0 4 60 76 79 84 91 99 100 100 0 1 26 47 53 65 78 94 100 100 2 24 84 100 100 100 100 100 100 100 200 7/27/19R2 30,600 0 1 3 15 46 71 89 100 0 1 5 18 44 72 93 100 5 29 34 36 42 52 67 100 100 0 5 24 100 2 5 6 6 8 13 36 87 100 ---- Average: 0.2 2 9 21 26 30 45 62 76 90 100 1/ Source: u.s. Ceo1ogical Survey Thble 12 BED MATERIAL SIZE DISTRIBUTION 15292700 TALKEETNA RIVER NEAR TALKEETNA, ALASKA!/ W:tter Discharge, % Finer than Indicated Size in Millimeter O:ite cfs o. 25 0.5 1.0 2.0 4.0 8.0 16 32 64 128 --- 9/29/1981 2,910 0 100 0 3 8 8 8 8 8 13 100 0 2 52 100 0 1 3 100 100 0 7 100 100 0 2 18 100 0 11 100 0 45 100 0 35 100 7/28/1982 14,000 1 7 50 74 84 91 95 100 100 100 0 4 25 85 100 0 7 100 100 0 100 100 9/20/1982 14,600 0 6 100 0 5 22 65 100 100 0 4 38 80 100 0 1 3 30 100 ----- Average: 0.1 0.4 3 5 5 6 8 15 57 100 _1/ Source: u.s. Geological Survey Date 9/30/19Rl 7/26/1982 j_/ Source: Thb1e 13 BED li-1ATERIAL SIZE DISTRIBUTION 152927RO SUSITNA RIVER AT SUNSHINE, ALASKA!./ Witer Discharge, % Finer than Indicated Size in Mi11nneter cfs o. 25 0.5 1.0 2.0 4.0 8.0 16 32 64 128 ---- 19,100 0 100 0 58 100 0 100 100 0 18 100 100 0 41 100 100 2 47 64 67 69 74 86 96 100 100 0 36 100 0 52 100 95,200 0 2 18 100 100 0 8 54 100 0 4 31 100 0 1 3 5 ll 23 38 53 62 100 0 1 15 100 100 0 2 4 6 12 23 64 100 100 ----- Average: 0.1 3 5 5 6 R ll 23 71 100 u.s. r~o1ogica1 &lrvey EXHIBITS SUSITNA RIVER / DRAINAGE BASIN\.,// ,..,. ..... I I I I I I I I I I I I .... ---..,-" / / / / ,..,.-' / ' ' / " / ' ", / " ..._~...; ' SOURCE: SUSITiiiA HYDROaECTRIC PROJECT LICENSE APPLICATION, EXHIBIT E, FIGURE E-2.1 ' / _.,.... ' '\ \ \ lli>.RzwiA.Sc:osusiTNA JOINT vENTURE oecEMBER, 1993 / / / / I I I I / / -..... ..... ' ...... ............ ' ...... / / / / /-."':_ ~------, ..._. SOLE O~==~·O.._==~ZD .. IL.!S EXHIBIT 1 -.-.... .,._ ' \ NOTES• I •. cONTINUOUS WATER QUALITY MONITOR \, I I I . INSTALLED. 2. OATACOLLECTION(JUL·SEPI981 Al'iD JUN·SEPI982.1 3:c'ttiE t:Ef"tEifi!EFORE "EACH STATION NIIM"E IN THE TABLE IS USED ON THE MAP TO MARK THE APPROXIMATE LOCATION Of·TJiE STATIONS. )d' I I I STATION (ALSUSITNA'I'IIVERNEAR DENALI (B) rJiiilrg:~R~~~~ NEAR CANTWELL "' z UJ 0 "' .. .. "' "' ~ w ., ... .. " IL t; ~-- ::E .. 1-IL ~~~ ~ ... 0:: ... ., u "' X X X X ... 1 ... "'"' :;;) a: ~-~ >-.... a: 0 ::; UJ "' Q. 15 3 ::E ...... a 1-Z 0: lri~ "' ~~~ ~ ;1: il:j<n X X X X X (C) SUSITNA RIVER NEAR WATANA DAM SITE X X xl x (D) SUSITfi'!A RIVER NEAR DEVIL CANYON lx X (E) SUSITI(A RIVER AT GOLD CREEK X X (F) SUSITN~ RIVER NEAR SUNSHINE X (G) SUSITNii .. RIV.ER AT SUSITNA STATION X •x (HI MACLA'IEN RIVER NEAR PAXSON X : (I) CHULITNA RIV.ER 'NEAR TAL~EETNA X i I (J) TALKEETNA RIVER NEAR T"..LKEETNA X X (K) SKWENtNA RIVER NEAR SKWENTNA X X (L) YENTNMIIVER NEAR SUSITNA STATION X IM). SU_S~TNA_RIVER NEAR TALKEET~A SUSITNA HYDROELECTRIC PROJECT SUSITNA RIVER BASIN AND GAGING STATIONS X X X X X X X X X X X X X X l( ~I ::; n. ::E .. ., 0 UJ .. !;( '3 ::E 0 "' :::; "' 0 X X X X X X X X J{ -"""""'-' "'-"":":·. ---~-. ----------------. -~ LIJ > LIJ ~ 4 LIJ Cl) z <[ LIJ 2 LIJ > 0 ID <t 1- LIJ LIJ 1.1. 80 NOTES: I. TALKEETNA a CHULITNA RIVER PROFILES- BASED ON U.S.G.S. CONTOUR MAPS. 2. SUSITNA RIVER PROFlLE-BASED ON THALWEG ELEVATION. .SOURCE: R&M. "SUSITNA HYDROELECTRIC PROJECT, RIVER MORPHOLOGY," 1982 TALKEETNA RIVER I I I I I I I I I I I I I I I I I I I /· I I EXHIBIT 2 I I I I CHUI.ITNA RIVER I SUSITNA RIVER PORTAGE CREEK I I GOLD CREEK I I SHERMAN / .? CURRY PARKS HIGHWAY / .I BRIDGE (SUNSHINE) ~ TAI.KEETNA ~ 90 100 110 U.S.G.S.CHULITNA &AGE SITE 120 130 RIVER MILES 140 150 160 HARZA, EBASCO SUSITNA JOlNTVENTURE DECEMBER,1983 SUSITNA HYDROELECTRIC PROJECT RIVER PROFILES l' SOURCE 1 RfM, "f./YJ)ROGI<APHIC SU/.?I/£V.S, CLOSeOUT REPORT_ 1'1.91. /~~ ~-,~ r" ~ [J ~~ ------,------------"-=-~-------------·--------------- 1?11/EtY Cl['oss )Ecrtotlf LorAT/tJtJ X BED /1119TE/rl/jL S-9M?LtAJtj-L(JCATIOAJ tiARZA, EBASCO SUSITNA JOINT VENTURE DECEMBER, 1983 MIUt fC~ t. til . ·. I t 1 I \ ... ~ .. c .... ;~·• SUSITNA HYDROELECTRIC PROJECT LOCATIONS OF BED MATERIAL SAMPLES COLLECTED BY HARZA-EBASCO HARZA-EBA~CO SUSITNA JOINT VENTURE DECEMBER, 1983 MILlE I I 1 1 SUSITNA HYDROELECTRIC PROJECT LOCATIONS OF BED MATERIAL SAMPLES COLLECTED BY HARZA-EBASCO cnm ~X CD :C r-t - NOJ o::j -n ww ---~IV£/( CA'oSS SECTIPAJ LOCATft)tV X BE/) MATER/IlL S-'JMPL!IVo/ LtJCATION HARZA. EBASCO SUSITNA JOINT VENTURE DECEMBER, 1983 1 1 SUSITNA HYDROELECTRIC PROJECT LOCATIONS OF BED MATERIAL SAMPLES COLLECTED BY HARZA-EBASCO cnm :::rx CDJ: ~-wm 0-i ...... ww • , ..... / 9 ..•. 8 .... i ch£·C:; . 7 .. -~~;=- 6. --~'o-=t 5 6 7 8 9 ·:·:. . : ;; ;. . . -~ " ·':i· c . E.'_. . 0~,: ~':~~ ~·-: .. , .: . i ~ :.:; . :::: 0 =~~ ,.-~:'.~. .. : .. ,..: .. . •L 5 6 7 8 9 •'i i -l"~j-::i '"': "J -· . i"::c '"'< . :c::: 2 . 3 '""'-= '"~ !-= p ~:c': .if, ""'~'"'·'~' :~ · :: · ~I""T ''=~"'""i":O 5 .•.. : =c-=-:=.:::-o: :-:·:::.,. · ·c ,.,_,: ::: Cj :.=-c .: 1:==::: . : :;::-T :: :-:: 1-=j::-:j ~-: 1 . 4 ...• ·==-=~-=; --~~:::::-:i~: ~:~=-~ :::1::~ J I =-r---:· :L ·: .:.+---+-'1--:: i . 6 . 5 . 4 j··-_., 3. ~ ~ ~ ~~ E 2. "' ' " ' ' " ; I I 'I I " ,, I ' .,. UJo I I .d • l I: If 6 7 ~ s r•. 1 HARZA-EBASCO SUSITNA JOINT VENTUfiE OECE':"BER, 1983 . I i · . . '' il l I 4 ' ' I I I ' ' 5 6 7 8 ~(000 . :,l ., ' .. 1 1 1 I ' II ' 2 ' 4 G 7 B ' '. 1 l 2 3 456789 ~ ~ 4 5 6 1 ~9 1 . ' ' . -- II • I I .II ' 1111 4 5 6 7 8 " . . ~ l ! ''==¥" I c ... = .1 t SUSITNA HYDROELECTRIC PROJECT ~ SUSPENDED SEDIMENT RATING CURVE .. ~ SUSITNA RIVER NEAR ANTW :t,,_, A.fiSKA ;;:= I ., " '" I I I I I ' I I ro:~ot>o r "r~""'" ' 9 1 6 7 9 ·.:z: "> ·:Jl i ~ 'm ''" :> ... j8 Ul c: ... . ::; z ·> C; :~ < ~· c: ll m 0 [!l m ;!: '" m ·"' • "tO ,.!!: I ,9 9.99 9 ~ L<>llO 9 3 2 L I= t-1- 99.9 99.8 i i I i ; i i i i i i ''· II I I!! _l ' r ~~ l 1 · I !! li-'1 [I! 11 1-- 46 8043 5 2. :..;_;_ ... ; j; J. ! t- .- 2 '. I Et= f=,_ f- H - 1 0.5 ' ! " i o·• 0.1 0 .05 I 1- 1- 001 10 g B 6 5 2 • 5 6789 1 iii ! !!I 1-1- J J 2 I I 2 ~ en ~ "' ~ ~ w "' :J: ' ' '!,. 1:: Ll ~ ~ ~ ~ ~ w ~ ~ R ~ R' ~ ~ ~ ~ ~ t "' ~ ~ <Q t( ~ ~ ~ ~ ~ < <;j ~ ~~ ~ ~ "() " j::: >::. K ~ ~ ~ 1::: ~ ~ "' ;J: I~ ~ ~ "' ~ "' ~ ~ ~ ~ ~ "' ~ (5 ~ <..J V; "1 I I@ + ~ I ~ ~ ~ C\1 -.: ..., .,. '0 ' .. " ~ "' C) !:! :'!! .: w "' ::;; w u w 0 w 0: :> ... z w > ... z g <( ... ~ iii :> ., 0 u ., :li w ;5 0: < :r 27 ® 140 + C!w:s SECTION Sul!lll')'c:P IN 1 9 c I CiiO<> Sccrtotll Su11vq<o /d 19.?2 (I(OSS SECTION 7"11•1'1 lbpOC,h"/'/11(. M"'p SuaR£rJOI l3oYtllMI?Y S 1/1!3/ll'/IOf NuMBFI', f?tVEil r1tLE T~o'1 Mount ~ I it; II) w ..... :;: lw X ~ ... );! ia (.) " ~ <! cr: w ~ ~ ~ t "- "" uo:g; SJ :;} ~ f ii:w:::l ~ ~ t 1->11) ~ t u-o ~ ~~ .. wo:z •j ./I ~ ., ( ...J<!<t: § .wz"' I ~ "' ~ Ot-z " ~ ~ " ~ IU cr:-o ;: 'Q " 0~- ~ ~~ ~ ~ ~ .. ?;:CI)t; 'a :lj ~ ~ <! ~ tl ~ "' "' 0 .. ~ ~ z (/) ~ .:3 t5 ~ 1-II) I iii 0 + :::J 0: le II) t.) I 1:;3 ~~ '. ffi "' ::; w ~~ ·~ ,::> iffi '> ..... z 1,~ i~ !~ :~ 0 ·(J -~ w < ~ I<{ :1: lOCO 100 10 1.0 GRAIN SIZE IN MILLIMETERS C068LES GRAVEL SAND Coor-se F me Me:k•m Sample No. E.le-v'. or Depth Clo ssificotic.n Na1\VC. LL PL PI GRADATION CURVES HARZA. EBASCO SUSITNA JOINT VENTURE DECEMBER, 1983 1 f,,....e SILT OR CLA'f tSUSITNA HYDROELECTRIC PROJE SUSITNA RIVER SIZE DISTRIBUTION OF BED MATERIAL cn n J---------------if > HARZA ENGiNHRIN:J CO., CHICAGO ~ ·:! APPROVED.. . -0: J--~~~~~~~~~--~~~0 = DATE \iiG.!'10. ;; a C~:s:.~LES -j f! :·t Of C :;:nh ' lN.:::t \Ate Sut~~ !~ N-:>. Ctasstf;cat!on LL I 1 l l GR/~OATION CUR\'ES SAND F.r.e PL ?I SILT 0R Ct.'J lsuSITNA H~~~LECTR IC PROJEC~'i SUSITNA RIVER SIZE DISTRIBUTION OF BED MATERAIL i C/lm ~-----------------------------~x hAtlZA ENGliiH:iHNG CO., CHICAGO l£ :I: .... _ APPROV[O.. 1\.lllJ ~0-A_T_E~--~~----T,~-W~G-.-fJO~.--~----~~ "-~·-n=et t"'t'rt41111Ute .. ..-.-..~_..-..-w,,..~.,..rllt_t_=...,•-·----•••------------·---------------"----------------... l\.l (X) HAAZA -EBASCO SUSITNA JOINT VENTURE DECEMBER, 1983 i I I I I i I I jftil !- I I Tt ~ lij 33 -...} I i - I I : (_ I ! I --T I I I I I I I. . I I ··-+ i I I i i \ \ . . I._,.. .,~ I ' ' I I !·~ ; I 1 I I • I t I I i ! I I I I I r·r, : .. ! I I ~-I· : 1 I 1 I : I I ! i i- I I . , . : I I ' I • t/'~1!-·r I ' ' I ! I 1 I J' 'I~~· 1 t 1 ' I A J I ' I I \ l I I I r -: l . I 1 I I ! I ! t I I , ! I : j : r 1 I 1 1 l ~ ~ • ~-··+·· r ·• .• . I:: -~ I i I I ! , : I I I I : i f ' ' ! :. I I T ' I I I I I I : I I TTl·::; l I ' I ' i ;-, :tk : -' + . I -' . : I . ' . I . . S"r1 Tl~:r (i£~11 I l I I -l I : j I ! I I T ' . i __ :! _I __ ~, .. , 1 0 .. I·· ! -l ! '···j-~- 1 <fj"' 1 : : .O:t'f"4',, ' . l I I I : ! I .I i l I ~ . I 1 HARZA • EBASCO SUSITNA JOINT VENTURE DECEM~ER, 1983 I : I I .... _..~.._, ! ·t -1 j I ' ' I 1 i I I I I I I ·+ I I I I I l i·· j I I : ~·-·1--; ' I I L. I I l ' ' --~. I .j i I ! I I I I I l ; ! : I itP4 : : r+~p : I ' . ,:.· ' , : l . . . . ' ; i : . I I ; :. SUSITNA HYDROELECTRIC PROJECT SUSITNA RIVER CROSS SECTION 1 --1 I I j I I I I I I : I j I I ' l i -1 I j I I j I .. i : ~ ; . , I i 1 T!T·~ ; ; ! ~ , lo, ',. : j, .................. _l_.~ ..... -~·-··· -~·~~--.J. ........... _ -··. ~ •. ~--;... ... ..: ••.. ;.... .1--.h~ ........ .,-••.•• !. ... ~ _..r ·•-. 112 //0 ;o8 ;o(; J, to4 "~ /oZ /t>o t!~ OJ·;.. t-. :]. ~ ::! r ,j I . I I\):' I .J _; :.:L ._.[".""I EXPLANATION -----May 27,1971; 0• 37,400 ft 3/s (1,060 m3/s) --July 2,1971; 0=74,600 tt.3/s (2,110 mJ/s) VELOCITIES, IN FEET PER SECOND Aug.11,1971; 0= 171,000 ft.3/s (4,840 mJ/s) {METRES PER SECOND IN PARENTHESES) ........... Oct~ 13,1971; Q not avai I able Aug. 11 July 2 30 I 0.2 (3.10) 9.7 {2. 95) Pier 2 I I li.D (3.35) Pier 3 9.4 {2. BB) Pier 4 .20 ~0-----1~00--~--2~00-----3~0~0-----4~00~----5~00----~60~0--~-7~00--.--~B0~0-----9~0~0----~~--~1100 STATIONING, IN FEET· ~ovtrcE .-A.lotrM"N 1.1. W ''s-cout~ AT S'EL:EC7£1? /3RtPt;-E ) ) S"ITES IN /JLASkA, '' WATEI{ /(ES(JUI(CFS INIIEST/(ji!J Tlth\1 3 2 -7~ us,c;.s /'17S: .J .., ) • HARZA-EBASCO SUSITNA JOINT VENTURE DECEMBER. 1"983 SUSITNA HYDROELECTRIC PROJECT RIVER CROSS SECTIONS SUSITNA RIVER AT UPSTREAM FACE OF SUNSHINE BRIDGE m >< ::r: m =i ..... w I ' m X :c tD -1 ' I . ,. ' .. t.: ----~ 1 I ! · ... m X :r: OJ -i ...... tn jOO 2 4 5 6 8 9 1 Q -----I 7 ____ ~cc' 6 .•. ~:: = '' i x8 I' ·, "' " ::= F' != "-~ 0 ? II I' ' I I I I I i j I II I 1'' 1 I , I f+ HARZA-EBAsCOSUSITNAJOINTVE~1983 •• ~;j 1111111 11!1 illllllifll!. lj> 1" -~ ~ 5 -~ f 8 91: 2 3 ! I !000 2 4 5 6 7 8 r 11 I i 't I Ji '!,~~I _, : Ll \II 'll It !II; I i i :1: ll 11 I , 1'1 I 4 5 6 7 I I .•: !ii' -~- j--L_ .I: ; f-H +--~ I ill I I ' I I II I I 8 9 10"" 3 1 3 4 5 6 2 ' i ~~ exi-t1srf 16 ~t-- -~ -· 5 -___ Q = ' l--- -.-. --- ·-·-·--------·---·---,-- ,,_ "''-· -='' :•c:::;::.:.: c: ic.:: : :' !::' r::-:-1-- 1·::1'--· l:::c::;c 1- i-+1 h+: '' ' ;:, : ;: I I •r !I i : .. 4 -·~ - I ''i 8 9 tqooo . :: c:c i : F--" I : '::=:I·_-_ I I 1-. 2 :;r I !il ' I" II r:r::!~o r: lc::::~:c "' ,,~, I I !I 3 'r' '"' 4 ., I i : -8t I ! Q • .;;:-2 ~'' 7 ~::.;·:::t::: 6 f;=~_::..;.:: :-:1-----re-tch SUSITNA HYDROELECTRIC PROJECT ., ~-2 BEDLOAD DISCHARGE RATING CURVE SUSITNA,R~VER ,NEAR TALKEETNA ' . _ ' '1]1 :I I.' It I I Ill I I .II< i ;I• I .!: ; ·,I fill ill il.cl·- I il' 'r•:: : -cr iT,,~ 1 5 6 7 8 9 !~ceo 3 4 5 6 7 9 ~ 9_ 8 7 6 5 ---- 4 3 .. -- x8 3_ ? 2 = c----- ---- 4 toO 5 6 7 8 9 I;_;__~-· 2 I 3 2 4 4 ! -"-'-!'--- ~--~ ------_-:'::--r=:-:"::: =c. 2 ' . :__~~'-T -~___;_:::.=;. -,---:-h--7 •.•...• --~-. -. I! 'I , I ' j; : ii I •I " I I I IT! 'I II ill I• I I \! [ l 1 j 3 4 56789k.w 2 I I 3 I 4 I II I .11 ' i ! 5 6 7 8 9 != -'- c i --1- l-'·FI:'-:::i·~--1-'- 1 :---'-'--" f--+·· -.. ! _, ... --' 'I ! I:! j] l'3l>t?O 2 2 2 3 4 56789' ":l;l--' ' IJI '' ! 'i ;.: : l I i 1<\JA-'f·t ! ! 4 5 7 8 9 1 !A! i: !.__ 7 .. 6._ 5 4_ 3 ..... ,,_ 4 to<> 5 6 7 8 9 8.' 7. 6. < 4_ f-~ ' ? ' I I I I '" )o 4 ,. 7 ' 9 (<>0 -________ c__ ___ __ HARZA-EBASCO SUSITNA JOINT VENTURE DECEMBER, 1983 I 2 3 4 i I ,. ' ' ,., i I 2 3 4 I 1000 5 6 7 8 9 :' I I i 6 7 8 9 ' ' I I I 2 4 . -,,. :·--1--·-·-· : II ,, ' ,, : ., . ' I r:t: I 'I 1: I :II i1ill i' I ill<!!' i li· I '. 1 ! 2 3 4 5 6 7 8 9 / . !:=-+--:-:-----· :'·: ==-~-+:.::l=±:c,_:_:cf.::cr:•::c: .. -'7 t---~!==f.:::T:I ~::..::.~;::; j.:.: ;::;:: ~---t-: :··: -, !·-.. I i-- f'-j_ !- ~'"-'t:C~tl'"o:IL~':-+--:,4_· ~ •>:·c:---=: ~"""~--·-kcf.:c b~-'l" . '"'"~ ~ITS~ r::·,::c:c:::r::::;···-'-'-:, lqDOll ! 2 3 I ·il J 1 1 i 4 ::C:·.'c;'fc'-"o'i''O I :C E:c',~f.'' _::! :, ':-· - L: 1-""''Y" ::: c:::-' • :-.:~::. i ,; .\:: -L. r=--·~-~ 4~=·:=. ~ ::: ,_ :+ L -_ F-=':.-=j='~+-• ,, ~~=~r T • "-.• :_:'_"'::i:::-c~_. ::':C"F -: -y -:-, , __ ~,.-" _,;::-T=::-:,,>.•• ,, '+ ;._: _: __ :c:c::_:cf'.:CC::t---I ---~ .. ----!:~-:-,---i·-1----1-, ______ _ :--.,--'.--t·--~.:':':-" f:-'· -1·-+------.:. I I ·-.:::. I I' I -----~ ±±:i::f:-+-.;;;6.,;- -f'~;?:::"f"~' --::·:' ,-: : [:C{'. ;:io:: .:: r:=;:::~:c-~c: -' -. ' I !II 1. Iii ,. _, i·' 4 s 6 7 8 4 l ~----~~~~~~~~~~~~~~~~=c~~~~~~~~~~~~~~~~~~~~~~=F~~~~~~=r~~~ 6.- 4 -- 3- 2. 7--- 4 r - i 1- 'I II: 'ill 3 IIi i 4 !iii r:' 'II 7 8 7 8 9 --c -.:::. ,:d·.J, )'~CPl." l i 4 5 6 7 8 L i 4 s67s:f":" I ---· HARZA. EBA_sco susiTNI\.ioiNT veN-ruRiioeceMa-eR-:-ls83 i 2 I 4 .1 3 4 567891 3 4 56789 8 .. cc ~,c .. ~ 7. r=ccccc,o- .~, i' 5----!=-"-· 4 ~c:==~-:=: 4. 1----·-· ~• . ~~I I I t 1 1 I 2 I I I I':' 1''1 I • ,I f'fT j• !il 5 6 7 : ~~17 1 HAR~-EBA~O SUSIT.NA JOINTVENTURE DECEMBER, 1S83~ 3 4 56789 . . t~'~'F'c i~L~jc,:LEi~ ,-· ~.c:j . -·---'--,~· iH ! 'I 4 6 2 4.?6789 .+;---·1-~-1-f-- •I 'I it f· ' l 2 1 ... 4 ~­ ~ I' 1, I' ;so f+: ' /.0,~6'0 ! I 5 6 7 8 9 ' 1 2 4 5 6 7 8 9 -:-•!~~ :::'_f~ : :•c.:-o::" • --"'= "''':L•:.:•.i: _, -.. ,;:;:-'-:-:: :-------~=~i':::-::J_::_:• j_c::i_-~ , J~j I, ~ J~'S· -···~·=ceo.•. '~-:~.e;·;:;-•::':--.:::.h:-;,;) . . .. ~ • p::b t8 •. ' ' SUSITNA HYDffOELEGTRICPRiiEC'f BEDLOAD DISCHARGE RATING CURVE c.z r~•CH~~!!N~ £11VER NEAR TAL __ K0Er>E::r~I.~N~.~-A.;rir R rvr nUNTH5 ur II,UGUST AND 51::1' 1 t:MI>r:: :j! I ' , i /""-"~'"' I 7 8 9 4 5 9 1 9 8 7 6 5 4 3 2 / 1 9 8 7' G 5 4 3 2' HARZA • EBASCO SUSITNA JOINT VENTURE DECEMBER, 1983 " 4 0 4 r • ... • • .. . • '! z ... u ::: i • • " . .. . .. :t 0 c "' :a ! 0 1:! 1: .. ~ • ~ . >I .. .. ~ u ! .. .. .. • 8 • 8 ~ J 7 t .. • • 0 0 .. .. .. . ... 0 :t 0 .. • .. • ~ • . ~ • • • . -.. " H ARZA • EBASCO SUSITNA JOINTVENT\JRE OECEM8ER. 1983 a 8 7 6 5 r i 0 4 z • w • 3 . l _, • y z l "' 2 .. ~ & • & • ... .. d & 0 • .. ~ ! ~ ! a ~ • ru • :: ... .. .., l ! " 3 .. ,., .. • , • 8 l! I 7 1 .. ; ( 6 • 9 5 .. . . u 0 & a .. • . • • . ' z t .. , . . ~ .. ' .0 1 2 2 3 4 15 Q 2 3 4 I 8 2 h RZA . EBASCO SUS ITNA JOINT VENTURE DECEMBER , t 983 . .. l.,ao~~~-+-6.¥- 1 i 5 40HI++"....,...,J..-+_..._.,......,..'"""*it+i-+-+- ~ Somple ..,:, ElnorOepth. Clo ssificotion No1WC LL PL PI ··---·-----"·~-~-----------------------------------------~------.__. __ ----·-·· SlJ§ITr.JA I-IYP RQ§ ~§CTBIC PRQJJ;GT1 .·. 'f. ,.,, .. -- . '·. ·.····'',' ·,., }0' ~ . ...,, .· . '' . · ' -' T' ·. .---·-~sTze oTsTF\YruJTIQN~QF ·: 1 -~.11 · . BED LOAD .·.. ' · I 1 ~ 1lsu~nrA--RiVeFfN'EAifTAid<~~e,.N'A' 1 ~-f I :r: .. i,.:. UARZA ENGINEERING CO., CHICAGO _1 I:Qi APPROVED ................... , . .. .. . :if: DATE OWG.NO. ~~~ GRADATION CURVES tO GRAIN SIZE IN Mll.i..tMI!TERS .· Sample No. Elev. or Oepth Ctauification Na1WC "-L Pl pt .. .· --~ f---- ___,....,.--f-·-· -. ·-··-f--·.·. -'.· •+ _ _._.........._ --~ - GRADATION CURVES .·.· 0.01 -------------~------~------------------~---· ~---~-:- §USITNA HYDROELECTRIC PROJI:_C!T '--~-' -• -··c .. --• • '· ·••• --, ·' ,'-·-'··-· ---·· '--·~ -~-~ '"'""'', .-"""" tl&l o»M< ________ ,.. rsi'ZE-15fstFfUiViiON~-Oif6iol.6Ao: !cl-luLffNA--·R .• \NeARTAL.KeerNA! ----~,-~~_...,:_····_· .··_. · ... _._· ._. _ ..... J~!- HARZA ~NGif<!fEfiiNG CO., CHICAGO 1.:=t· OAT....;;EA::.:..P..:..P.:.:,R.:;..OV::..:E:;.::O:.:,.;· ·.:.:.· ·.:..:.· .. :..P" :...:.· ~..:..:-~~-~:.;.;· ·;,..:.: ·.;...;· ..;..:.;..;.:...;..:.--ill~\ ~~~~~~~~~~~~-.~------------.---------------~-.------~~------~~1 _,A~~Qj.Wiia~:ilf~tY~Nl"IJAiffi~~~M:i~i;1•:~ 100 90 eo .... 70 :r C) I.IJ 60 ~ ~~ lt""t . ~--: I U1 ' f > al 0:: 50 ..... z iA: ... 40 z I.IJ u a: ~ 30 1! ,, l !: I I 100 10 1.0 GRAIN SiZE IN MILLIMETERS SAND C065t.ES Somple No. E!~. or Dr:pth Classification Nat VIC LL PL PI ·GRADATION CURVES -' :..'NO'Z. 30 0 w 40 z 4 ... ..... Q: .50 ... z l.iJ l.J 60 0:: w 0... 70 80 - 90 I 00 0.01 0001 SiLT OR CLAY SUSITNA HYDROELECTRIC PROJECT SIZE DISTRIBUTION OF BED LOAD TALKEETNA R. NEAR TALKEETNA m ~--------------------------~X 11ARZ.A ENGitfEERiHG CO., CHICAGO :I: ll' ~~A~P~P~~~O~V~E~O~.·~~~~~~~~~~ OATE WG.NO. 1'\l L-----------------------·------------------------------------------------1~----------~----------~m ' i HARZA-EBASC'! SUSITNA JOINT '_'~NTURE DECEMBER, 1983 U.S. STANDARD $lEV£ $1~£ u\'U!\.' : . :l ~~ ~ . N0 .. 4. ' l! \ft . _¥!__ '''T " ~~ I l ~ [· ll t .A,.. I ~·:<. r . i"• ~ [:tf: I I : [·--··-· -··--· I! ;"""' r, -·-····· ·• :_·_. " t..; Q< ., J J . -f.~· . ·._ ... -. [ ·-r. ~ lX , . I -·-- L-v .. .,.. i> •• 'I .. It 11 '~'-' .. i .-·_ ... .. > i\ 1\ I! _I ! ! ! M . ''!"" ··: ._: c~·; . -....... _-.-_ l\ I• ---l f' I! I tc '· r-·c·;· ~ ... 2~ it • (----.···'J ·.-_· I! ..... ....... I . '< ~ ·---~--I '_<{ !1.6' ~ I f ~ -:~ . lr'-·~·---•.·--.· l:""r---. ~ t v ...... I..: a --· -= ¥ "'"' (o ···:; .i ..IVN. ~ -_. ! ! f (j 1 ! L .A ._---_·--." .. ; ·-[I -··--._. \ \ ~ ·-""' -'••_ - tM~ ·. . !I ,.,.,..... ..... :'' .:t \ ~-' ·.-! ""'"" r ?' l j_ th ! ~ ' llt -.· r \ ,_ 1···-_· : r·' -:~ v n-., ~r •:\ jl:_ ...... ,.,.. r··-~-I-" it I ·-~ :\ 1 _ .. L--~-.<:.A. ,. Ls::. ""' 1-' 1-• _;, .I i "' ~ l tn ·7 r· -_ ·: _·-_.-,, : i I " ~ ~\ 0 1-'-,-._·:._· . ·-. _::ff ''',0'':;'/ I : ~ IUC I() --I -1.\.1 --_· .. , - $ampt.N4t, f.lev. or Depth Classific:Otion Nat~ LL PL PI -· .-_- . ----_ ·: -~ ., ·---. -.· _: _·,:·-: -. ,_.--: --.. ._. GRADATION CURVES -J~!9~ 2QQ :· I_ f' l1. _·';., i-'J. ~¢:"' .... •• h II h :; l fl I ..:i' :·--·--. -: t l t _--- 1 ~_... : ·-0.1 -- .n ly ,.· ··_· .· tO ~"" !.aA-.4 L) 1-9 t/G B ~--···-··-··· . ; .:> t->n . . t• 30 . :· - t!J lc:".J k:l.r. t.r .lb . 82 r ....... ·_ . -' . - .,.. .· . ' ,· ~- ( - ---·._--_ ''" I' -_--_--.-70 -· ._. . .,. .... I"' .- 61'\ ._----· , ... - -.-• 1nn 0.01 ().() .. •. SOSITNAtfYPRO~C'ECfRlCPAOJEc lsl~fojsTFfl·a-urloN iOfaetFCoA[fi, :sosrrNA-RTVE_R=Ar-'-sD-NSHI NE-, ~, · -··' · -~ ,' _ • _ _._ . -.-A<: .::ri --.,..,,•.. ·. '\ ___ ' EXHIBIT 28 46 8043 ~.999.8 99 98 95 90 80 70 60 50 4() 30 20 10 5 2 1 0.5 0.2 0.1 0.05 O.Ql 9 ,,-,, -~-' c~=--= §'':-c"C, B ~ 7 :7 .. c· .:::.c 6 I 5 -" 3 1 .-~="'' 2 ' ' ' ' ,, --- " -; -;A: / ,. '" " ---j ... "'"" ·"" ..... ~--·u '""'I ; -' -~ /~t:J#· ! ., ·! 8 ~ • ,-,··= -' --: c II I • ~ -~ ~ ' ., --. -' f---. . ·c: ._, .. , 2 ...... ------ . -~-· -·-- - ! --~~-[-~------ ~ ! II ! ' ,-,, . 0 ~ - -,. _, '- CCCC~- ~ --,,c 4 · .. cj 3 : 2. ' ,. '' ' ' '' •' '' I , 'i I ' U/1 I ' Iii; ·' !;I! 0,0/ ~.I (),~ ~-I z .r /Q ZQ 3o ~f) .!'1 HARZA-EBASCO SUSITNA JOINT VENTURE DECEMBER, 1983 'f) 1 :c·_ ----. .--~--- ' - . ; I -------- 70 ,f., 9P tr 91 '1f PM 9'1."' 99, 9'/ SUSITNA HYDROELECTRIC PROJECT DURATION CURVES BASED ON DAILY FLOWS WATER YEAR 1982 SUSITNA RIVER AT GOLD CREEK AND SUNSHINE 99.99 99.9 99.8 99 98 8 5. 4 2 'I.J \ !;-' ~ ' ~ ' L '" ·~ " "4 i : ... ' /"'""' 3 95 90 80 ' -------- EXHIBIT 29 46 8043 70 60 50 40 30 20 10 5 1 0.5 0.2 0.1 0~1 !CI .. "- ~ 9 :=o~o= ...... ' ~- SUSITNA HYDROELECTRIC PROJECT DURATION CURVES BASED ON DAILY FLOWS WATER YEAR 1982 CHULITNA AND TALKEETNA RIVERS HARZA-EBASCO SUSITNA JOINT VENTURE DECEMBER, 1983