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I I I I I I I I I I I I I I I I I I II SECTION 6 MODEL AND RESULTS 6.1 MODEL DESCRIPTION An Excel Spreadsheet model was developed to simulate the various inflows, demands and pools sizes. The model was a direct solution, daily model. A starting storage value of zero acre-feet was assumed for each simulation. The storage value for the next day was computed as: L'lS = I - 0 Where L'lS = change in storage, I = inflow, and 0= outflow (demand plus evaporation) Evaporation was computed based on the reservoir area vs. capacity curve for Chatfield Reservoir (D. S. Army Corps of Engineers, Omaha District, August 7, 2000, see Appendix B herein) and monthly evaporation rates. Evaporation was prorated between the conservation storage pool and the rcallocated storage pool. If the resulting total storage after netting out the evaporation was less than zero, reservoir outflow was adjusted to set storage to zero. If the result was greater than the maximum storage allowed, a spill was added to the outflow. This process was repeated for every time step in the model. Charts were linked to the model to show the results in graphical form. The normal maximum level of the Denver Water operations pool in Chatfield Reservoir is 5432 feet MSL; however, this pool level fluctuates. The three reallocated Chatfield Reservoir storage pools were assumed to be on top ofthe fluctuating Denver Water operations pool. Consequently, the water surface levels for the reallocated Chatfield Reservoir storage pools will also fluctuate. For example, the water surface elevation for the full 20,600 acre-feet reallocated storage pool will not always be 5,434 feet MSL; actual elevation will depend on the volume of storage in the Denver Water operations pool. 6.2 MODEL RESULTS 6.2.1 General Modeling results for the combinations of three proposed reallocated Chatfield Reservoir storage pools and five potential target releases are presented graphically in a series of five figures for each reallocated storage pooJ/user: . Figures I-A through l5-A present inflows to storage, spills and storage for each scenano. Figures l-B through 15-B present demand (target releases), the actual releases from reallocated storage (met demand) and evaporation. . P :\Data\GEN\CWCB\Chatfield\Repon 12.02\RevisedChatReportl 03\Report2-03 _doc 13