Hydrology and Hydraulics

Hydrology and Hydraulics

Reservoir Configuration

Table 3 Dam and Outlet Configuration for Alternatives.Notes:1 The spillway weir coefficient was calculated from the given spillway length and a spillway capacity requirement of 50,000 cfs

AlternativeCurrent ConditionsFlood StorageMulti-Purpose (Hydropower)Total storage capacity (AF)080,000145,000Reservoir surface area (ac)NA1,0001,450Bottom elevation (ft)NA1428.61428.6Spillway elevation (ft)NA1646.61696.6Dam crest elevation (ft)NA1666.61716.6Dam crest length (ft)NA1,4501,800Outlet capacity (cfs)NA2,0002,000Spillway length (ft)NA500500Spillway weir coefficient1NA1.1111.111Spillway maximum capacity (cfs)NA49,64049,640Power plant minimum operating elevation (ft)NANA1606.6Power plant capacity (cfs)NANA732Power plant tailwater elevation (ft)NANA1436.6

Table 7 Multi-Purpose Reservoir Power Release Schedule

DatesPower Release (cfs)October 1-November 23140November 24-March 31732April 1-September 30140

Table 8 Multi-Purpose Reservoir Overall Release Schedule (November 24 to March 31)

Reservoir Pool Elevation (NGVD + 1,000 ft)Description of Release1428.6 to 1594.520 cfs bypass releaseNo power release1594.5 to 1606.5Ramp to 140 cfs bypass release (10 cfs per foot elevation)No power release1606.6 to 1631.6No bypass release140 cfs low power release592 cfs high power release1631.6 to 1657.0Ramp to 1,268 cfs bypass release (50 cfs per foot elevation)140 cfs low power release592 cfs high power release1657.0 to 1716.61,268 cfs bypass release140 cfs low power release592 cfs high power release

Table 9 Multi-Purpose Reservoir Overall Release Schedule (April 1 to November 23)

Reservoir Pool Elevation (NGVD + 1000 ft)Description of Release1428.6 to 1594.520 cfs bypass releaseNo power release1594.5 to 1606.5Ramp to 140 cfs bypass release (10 cfs per foot elevation)No power release1606.6 to 1631.6No bypass release140 cfs low power release1631.6 to 1643.4Ramp to 592 cfs bypass release (50 cfs per foot elevation)140 cfs low power release1643.5No bypass release140 cfs low power release592 cfs high power release1643.5 to 1668.9Ramp to 1,268 cfs bypass release (50 cfs per foot elevation)140 cfs low power release592 cfs high power release1668.9 to 1716.61,268 cfs bypass release140 cfs low power release592 cfs high power release

Flood Modeling

Figure 3 Reservoir Water Surface Elevation and Outflow 100-year Event, Flood Storage Alternative

Figure 2 Comparison of Flood Storage Alternative to Current Conditions 100-year Event, USGS Gage at Doty

Table 6 Flood Storage Reservoir Emptying Time after Flood Events

Notes: Time is calculated starting from the time when the reservoir begins storing water (reservoir inflow > 2000 cfs) and ending at the time when reservoir outflow is equal to reservoir inflow.

EventEmptying Time (days)100 year2450 year2110 year152007 flood50

Table 5 Comparison of Flood Storage and Current Conditions Modeling Results at the USGS Gage at Doty

Notes: Current = current conditions alternativeFlood = flood storage alternative

EventPeak Flow (cfs)1-Day Average Flow (cfs)3-Day Average Flow (cfs)7-Day Average Flow (cfs)CurrentFloodDiffCurrentFloodDiffCurrentFloodDiffCurrentFloodDiff100-yr39,35317,433-55.7%24,33110,914-55.1%13,6647,003-48.7%8,1924,941-39.7%50-yr32,56214,792-54.6%20,3989,473-53.6%11,8746,348-46.5%7,3444,631-36.9%10-yr19,8579,831-50.5%12,9376,740-47.9%8,2335,014-39.1%5,4723,941-28.0%Dec0763,10025,861-59.0%41,39017,476-57.8%20,3109,224-54.6%11,3935,798-49.1%

Figure 141996 Flood Hydrograph at Mellen Street

Figure 191996 Flood Water Surface Elevation Profile, Existing and Proposed

Figure 13100-year Hydrograph at Mellen Street

Figure 15100-year Flood Profile, Existing and Proposed

Figure 1650-year Water Surface Elevation Profile, Existing and Proposed

Figure 1710-year Water Surface Elevation Profile, Existing and Proposed

Figure 182-year Water Surface Elevation Profile, Existing and Proposed

Flow Exceedance Analysis

Figure 7 Exceedance Curves for the Flood Storage and Current Conditions Alternatives USGS Gage at Doty

Table 10 Comparison of Flood Control and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Doty

Notes: Flood = flood storage alternativeCurrent = current conditions alternative

MonthAverageMaximumMinimum90%50%10%FloodCurrentFloodCurrentFloodCurrentFloodCurrentFloodCurrentFloodCurrentOct2232263,9825,777181824246666478478Nov1,0081,0287,10213,444222289895835832,7312,411Dec1,3391,36717,22640,33250502482487967673,0933,103Jan1,3931,3708,24616,4131661663193191,0099292,9562,933Feb1,0331,0209,12819,1621331332192196586582,5182,029Mar8828675,3819,4701001002682686456451,8361,658Apr5855856,23611,0991141142202203923921,1241,076May2732732,1712,1717979113113212212506506Jun1611612,6022,60140407070121121275275Jul6767387387222235356060103103Aug43436626621717242434345959Sept60602,3212,3211616212130308686

Table 13 Comparison of Flood Control and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Grand MoundNotes: Flood = flood storage alternativeCurrent = current conditions alternative

MonthAverageMaximumMinimum90%50%10%FloodCurrentFloodCurrentFloodCurrentFloodCurrentFloodCurrentFloodCurrentOct79880014,60516,4001811812292293903901,6941,694Nov3,9393,96032,66138,4001771774734732,3252,32510,20310,200Dec6,1266,15738,79461,9003273271,3801,3804,1654,03514,09914,400Jan6,6456,61750,33358,5001,0101,0101,8431,8435,2074,99513,20112,990Feb5,2455,23554,16664,2007097091,4821,4823,5703,57010,48610,300Mar4,2604,24619,90821,9006016011,3611,3613,2353,2358,6848,593Apr3,0043,00734,21538,0006706701,2601,2602,2252,2255,3135,313May1,5331,5317,3607,3603943947067061,2201,2202,8092,809Jun9699695,8105,8102342344374377757751,6411,641Jul4004001,3401,340151151235235361361622622Aug2672672,1002,100117117177177236236372372Sept3443443,6003,600128128199199272272457457

Table 14 Comparison of Flood Control and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Porter

Notes:Flood = flood storage alternativeCurrent = current conditions alternative

MonthAverageMaximumMinimum90%50%10%FloodCurrentFloodCurrentFloodCurrentFloodCurrentFloodCurrentFloodCurrentOct1,0551,05515,10015,1002822823353355465462,2592,259Nov5,2715,29432,91638,8002932935935933,2503,25013,84213,800Dec8,6328,66045,69367,3005385382,1312,1316,1005,93519,60420,170Jan9,5179,48154,57860,3001,5801,5802,9002,9007,6707,37019,27019,190Feb7,7647,76452,37555,0001,1801,1802,2462,2465,7905,78016,36016,180Mar6,2336,22028,81529,6001,0901,0902,2002,2004,9454,94511,80011,800Apr4,3364,34132,01535,8001,1201,1201,9601,9603,3503,3507,2707,270May2,2142,2099,5709,5707377371,0301,0301,8601,8603,9193,919Jun1,3931,3937,7307,7303523526806801,1101,1102,4012,401Jul6256251,8101,810258258386386568568924924Aug4274272,5802,580182182311311407407558558Sept4874875,1605,160183183307307403403608608

Figure 5 Comparison of Multi-purpose Alternative to Gage Records USGS Gage at Doty Water Years 2001 to 2003

Figure 6 Reservoir Results for Multi-purpose Alternative Water Years 2001 to 2003

Figure 8 Exceedance Curves for the Multi-purpose and Current Conditions Alternatives USGS Gage at Doty

Table 11 Comparison of Multi-Purpose and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Doty

Notes: Multi = multi-purpose alternativeCurrent = current conditions alternative

MonthAverageMaximumMinimum90%50%10%MultiCurrentMultiCurrentMultiCurrentMultiCurrentMultiCurrentMultiCurrentOct1802262,6625,7772818482411766337478Nov7561,0286,30313,4443322104894275831,9392,411Dec1,3921,36716,39340,332105503112481,1007672,5853,103Jan1,3491,3707,09216,4131981663513191,1789292,4042,933Feb1,1291,0208,79519,1621791332312199926581,9672,029Mar9338674,4789,4701531002802689426451,4291,658Apr4165854,47911,0991641142202203213927021,076May2962731,0452,17116879182113234212501506Jun2101611,1612,6011544016570184121288275Jul1606729138790221393516160178103Aug13843338662541782241523416059Sept123609912,321321653211223016386

Table 15 Comparison of Multi-Purpose and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Grand Mound

Notes: Multi = multi-purpose alternativeCurrent = current conditions alternative

MonthAverageMaximumMinimum90%50%10%MultiCurrentMultiCurrentMultiCurrentMultiCurrentMultiCurrentMultiCurrentOct76380013,28516,4002111812602294373901,5291,694Nov3,6773,96032,50438,4002051774774732,1122,3259,44410,200Dec6,1826,15737,96161,9003823271,6051,3804,4054,03513,32614,400Jan6,6026,61749,17958,5001,0361,0101,9101,8435,1684,99512,74012,990Feb5,3335,23553,83364,2007547091,4881,4823,9063,57010,19310,300Mar4,3154,24619,43121,9006546011,3821,3613,5253,2358,2948,593Apr2,8423,00732,35638,0007206701,2591,2602,1782,2254,7705,313May1,5531,5316,2227,3604833947657061,2681,2202,8302,809Jun1,0179695,3955,8103482345264378297751,6481,641Jul4924001,2661,340225151335235462361693622Aug3632671,7402,100155117253177348236477372Sept4083442,6023,600165128247199364272529457

Table 16 Comparison of Multi-Purpose and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Porter

Notes: Multi = multi-purpose alternativeCurrent = current conditions alternative

MonthAverageMaximumMinimum90%50%10%MultiCurrentMultiCurrentMultiCurrentMultiCurrentMultiCurrentMultiCurrentOct1,0261,05514,59515,1003022823623355855462,1332,259Nov5,0035,29432,35438,8003212936125933,1073,25012,68613,800Dec8,6888,66045,50167,3005935382,4412,1316,3395,93519,01620,170Jan9,4749,48153,34360,3001,5791,5802,9122,9007,5507,37018,69819,190Feb7,8457,76451,40655,0001,2251,1802,2522,2465,9845,78015,70316,180Mar6,2926,22028,81529,6001,1421,0902,1822,2005,2274,94511,59111,800Apr4,1794,34130,15635,8001,1701,1201,9531,9603,3173,3506,8487,270May2,2302,2098,4329,5708187371,0881,0301,8981,8603,8493,919Jun1,4401,3937,6807,7304643527756801,1631,1102,3992,401Jul7176251,8311,810333258493386666568998924Aug5244272,3202,580221182385311522407660558Sept5514875,1225,160221183348307494403688608

Water Quality/Temperature Modeling

Figure 20Inflow Hydrographs Used at the Upstream Boundary (Doty Gage) for Temperature Modeling

Locations of Temperature Probes/Water Quality Data

Figure 25Riverwide flows simulated on July 15, 2010 for the baseline and multi-purpose reservoir scenarios

Figure 26 Riverwide flows simulated on August 22, 2010 for the baseline and multi-purpose reservoir scenarios

Example of Reservoir Output CE QUAL 2 Model

Calibration of Water Quality Model

Number of days Average Water Column Temperature Exceeds 18C For Various Reaches