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Table 6 -Maximum Gain Constraints <br />Reach Name Total Q (cfs) Q (cfs) er River Mile <br />South Platte 1-Waterton to Denver 192 11 <br />South Platte 2 -Denver to Henderson 182 11 <br />South Platte 3 -Henderson to Fort Lupton 195 11 <br />South Platte ~ -Fort Lupton to Kerse 499 13 <br />South Platte 5 -Kerse to WeMona 574 13 <br />South Platte 6 - Weldona to Balzac 315 13 <br />South Platte 7 -Balzac to Julesbur r 1,041 11 <br />Cache la Poudre - Ft Co]]ins to Greele 522 9 <br />Cherr Creek - Franktown to Denver 303 8 <br />Maximum Loss Constraint <br />To quantify the maximum loss that might occur in each reach, t11e analytical Glover equation <br />(Glover 1974) was applied by treating the stream as a parallel drain. The Glover parallel drain <br />solution quantifies the flow to or from a river based on the difference between stream stage and <br />grotuldwater levels, the duration of the difference, the area over which the stage-groundwater <br />levels occur, and on aquifer properties. Tl1e Glover equation can be defined as: <br />Q = iL (1-P)X <br />Where: <br />Q =Stream loss within the reach (cubic feet per second [cfs] ) <br />i =Calculated stage 1leigllt multiplied by alluvial aquifer porosity of 02 <br />L =Alluvial aquifer width (ft) <br />P =Patio of aquifer volume to be drained (a function of at/L~) <br />where a =aquifer constant (transmissivity /specific yield) <br />t =Time since one day of infiltration (day) <br />X = Reac111ength (ft) <br />The values used for the Glover calculations for eac11 reach are presented in Appendix D Table <br />D2. <br />Stream losses from the South Platte River and its tributaries typically occur during peak flow <br />events when the stream stage is significantly higher then average. Peak flows are typically <br />observed during snowmelt periods prior to the start of the growuzg season and duruzg localized <br />rainfall events. The stage height parameter (i) was estimated as the difference in stage between <br />peak and average runoff conditions. The timing parameter (t) is the duration of high flow <br />events w11en stream stage was elevated. It was determined by examining t11e stage data from <br />eac11 of the nine reaches during historical high flow events. On average, within the ma>1lstem <br />reaches, the high flow events lasted seven days so this duration was used in estimating the <br />maximum loss constraint. <br />SPDSS Phase 4 Task 46 Technical Memorandum -Final 12 <br />0~4i 10i0~ <br />