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I I I I I I I I I I I I I I I I I I I *( ) (2St)_ * (2St+l) C II + 11+1 + !1t - C Ot+l + ~ C = coefficient of conversion cfs to acre-feet per day It = Inflow at time t, cfs 11+1 = Inflow at time t+ 1, cfs SI = Storage at time t, acre feet St+1 = Storage at time t+ 1, acre feet 01 = Outflow at time t, cfs Ot+1 = Outflow at time t+ 1, cfs The left side of the equation contains variables given from the starting conditions (from Steps 3 and 4) and input hydrograph. The right side of the equation contains the storage and outflow for the next time step that are to be solved. The goal seek function (iterative solver routine) in Excel was used along with the outflow guidelines (see Step 4) and the stage-storage-discharge relationship to solve for the 01+1 and St+1 variables in the right side of the equation. The time step is advanced by one with the outflow and storage solution becoming the known variables for the left side of the Modified Puis routing equation and the solution process was repeated. The procedure is continued until the entire hydrograph is processed. The resulting hydrograph is the regulated 1 percent chance exceedence Taylor River below Taylor Park Reservoir. 6. Determine the Regulated Taylor River at Almont Hydrograph Flow. The Taylor River local flow contribution (from Step 2) was added to the regulated 1 percent chance exceedence Taylor River below Taylor Park Reservoir hydrograph (from Step 5) to create the regulated 1 percent chance exceedence Taylor River at Almont hydrograph. 7. Determine the Regulated Gunnison River at Almont Hydrograph. The East River hydrograph (from Step 1) was added to the regulated Taylor River at Almont hydrograph (from Step 6) to create the regulated Gunnison River at A1mont hydrograph. 8. Determine the Regulated Gunnison River near Gunnison Hydrograph. The regulated Gunnison River hydrograph (from Step 7) was added to the Ohio Creek at Gunnison hydrograph (from Step 2) to create the regulated Gunnison River near Gunnison hydrograph. 6.3.4 Starting Water Surface Elevation The starting reservoir water surface at the beginning of simulation was set at 9,328 feet (2 feet below the spillway crest elevation of 9,330) per guidance provided by Coli Stanton of Bureau of Reclamation (see Section 6.3.2). The guidance states that the reservoir would be operated for irrigation supply, to maintain a pool elevation of 2 to 3 feet below the spillway crest when possible. The simulation was started with the assumption that the reservoir was filled to the 9,328 feet desired water surface elevation stated in the guidance. 6.4 RESUL 1S The model was run with the initial reservoir stage as described in Section 6.3.3. The lower-level outlet gates were operated as discussed in Section 6.3.2. The resulting peak discharges are listed in Table 6.4.1 with the resulting hydrographs in Figure 6.4.1. The peak flows for the unregulated and regulated hydrographs developed by the spreadsheet model are listed as well as the difference in cfs and percentage. 53