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Show Final Report Hydrologic Model Analysis of the Provo River Basin locations. Prior to correlating with historic streamflow data, measured flows were naturalized by adding back in the historical diversions and removing the effects of transbasin inflows and reservoir storages and releases. The following methods were used, depending upon the information available: 1. If available gaged data included man- made alterations, natural flow was computed by removing those man- made influences. 2. If the historical, natural gaged record was incomplete, the data were extended by correlating with natural flow data in a long- record basin. 3. If the available altered record was incomplete, natural flows were computed from the available record, then correlated and extended. 4. If gaged data were not available, streamflows were estimated by correlating flow with physiographic characteristics, or by calculating a water balance using upstream and downstream gage records. Twenty- nine separate sets of natural flow data were developed for mainstream and tributary gage sites within the Provo River Basin using the above methods. Flow data for four additional gage sites were developed from other data sources and studies. Water balances were subsequently computed at each node to verify the accuracy of the extended and calculated flow data. The water balance adjustments were minor, and showed that the developed streamflows agreed with the recorded streamflow data within the accuracy of the gages and diversion measurements themselves. Following the development of all of the hydrologic data, the data were loaded into the PROSIM model, and PROSIM was used to simulate the historical flow that would have resulted, had conditions been exactly as predicted by the data. A comparison of these simulated historical flows with recorded flows allows the accuracy of the data to be estimated. These PROSIM results were then used to adjust selected data sets to more accurately simulate historical conditions. In the adjustment process, measured flows were assumed to be accurate, while return flow delay patterns, local inflows between gage locations, and diversion data were modified sequentially until the simulated flows matched the measured flows. After adjustment, PROSIM's hydrologic database was able to accurately replicate historically recorded Provo River streamflows. The combination of water balance factors - inflows, diversions, and return flows - are only as accurate as the January 1998 Page 13 |
