Point Flow Analysis Software for the Lower South Platte River

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additional river reach), all subreach gains and river flows are re- calculated on for that particular day and in the same manner as presented above. For the Lower South Platte River daily point flow analysis discussed in detail in this User's Guide (spanning water years 1981 - 1993), a negative flow occurring below a structure was computed 3,256 times, or 1.5 percent. A bar chart illustrating the location and frequency of such negative flow computations is presented in Appendix I. Figure 2 and Table 1 illustrate the procedures utilized to compute subreach gains and river flows. Figure 2 presents a river segment characterized by two (2) gauging stations encompassing five (5) structures (three (3) diversion points and two (2) inflow points). Table 1 indexes both the computed subreach gains and river flows associated with Figure 2. Figure 2 - River segment illustrating subreach gain and river flow computations. Due to the fact that Canal B is specified as 'Drying River', two reaches exist within the river segment portrayed in Figure 2. The upper reach is defined as being from Gauge A to Canal B, while the lower reach begins -at Canal B and extends to Gauge B. The total gain for each reach is computed by summing fluxes across each reach boundary. This results in a gain of +2.0 cfs (- (10 +3- 6 -9 -0)) within the upper reach and a gain of +1.0 cfs (- (0 +7 -4 -4)) within the lower reach. Note the zero flow boundary below Canal B. The total reach gains are then converted to a river mile basis by dividing the reach gain by its respective reach distance (7.0 river miles for the upper reach, 6.0 river miles for the lower reach). The resulting subreach gains are presented in both Figure 2 and Table 1 (0.29 and 0.17 cfs /river miles, respectively). The river flows occurring above and below each structure are the result of incorporating calculated subreach gains with fluxes occurring at each structure. For example, the water flowing within the river channel directly up river of Stream A is the summation of the flow crossing Gauge A (10.0 cfs) and total gain occurring in Subreach I. Total Subreach I gain is the product of Subreach I gain on a per river mile basis and subreach length (0.29 cfs /river mile x 2.5 river 9 ptflguid.wpd a o 1 v�d A yd N Riva 01 Chamd Sulbmwh 14 Suubr=& Subr=& Subreach " Suubft'M�1' Su1brm& " I II III IV v VI I C N Ct C, I V d iiiiii I I I • I Total Reach Oak - +2.0 c6 Total Rh G i. - +1.0 cf. I 029 cfdrim mile 0.17 cfs/dm m& Figure 2 - River segment illustrating subreach gain and river flow computations. Due to the fact that Canal B is specified as 'Drying River', two reaches exist within the river segment portrayed in Figure 2. The upper reach is defined as being from Gauge A to Canal B, while the lower reach begins -at Canal B and extends to Gauge B. The total gain for each reach is computed by summing fluxes across each reach boundary. This results in a gain of +2.0 cfs (- (10 +3- 6 -9 -0)) within the upper reach and a gain of +1.0 cfs (- (0 +7 -4 -4)) within the lower reach. Note the zero flow boundary below Canal B. The total reach gains are then converted to a river mile basis by dividing the reach gain by its respective reach distance (7.0 river miles for the upper reach, 6.0 river miles for the lower reach). The resulting subreach gains are presented in both Figure 2 and Table 1 (0.29 and 0.17 cfs /river miles, respectively). The river flows occurring above and below each structure are the result of incorporating calculated subreach gains with fluxes occurring at each structure. For example, the water flowing within the river channel directly up river of Stream A is the summation of the flow crossing Gauge A (10.0 cfs) and total gain occurring in Subreach I. Total Subreach I gain is the product of Subreach I gain on a per river mile basis and subreach length (0.29 cfs /river mile x 2.5 river 9 ptflguid.wpd