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<br />n-6...... .: <br />~/~- <br /> <br />T;.,&,b.,. ~/ ~ <br />/{;I??H~.r ~h <br />. R-,/.A/./ <br /> <br />- HYDROLOGY AND HYDRAULIC DETERMINATIONS - <br /> <br />Hydrologic Analysis <br /> <br />Hydrologic analysis of the Tucker Gulch and Kenneys Run drainage basins were <br />performed to determine peak discharges and flood hydrographs at selected <br />critical points along the studied streams. Flood discharges were determined <br />for the 10-, 50- and 100-year rainfall events assuming future developed basin <br />conditions. Table I shows the peak flow rates selected for hydraulic model- <br />ling. <br /> <br />Tucker Gulch: The hydrologic analysis for the Tucker Gulch drainage basin <br />involved dividing the basin into five sub-basins and utilizing the Colorado <br />Urban Hydrograph Procedure (CUHP) to determine runoff hydrographs from each <br />sub-basin. The hydrographs were combined and routed down stream channels <br />using the Convex Routing Method. The resulting flood hydrographs were used <br />to select the peak discharges for hydraulic modelling. Figure 1 shows the <br />basin and sub-basin boundaries; Figure 2 shows the discharge probability <br />profiles, and Figure 3 shows typical lOO-year flood hydrographs. <br /> <br />The basin and unit hydrograph parameters are tabulated in Table II. The <br />procedure used to determine the CUHP parameters is outlined in the Urban Drainage <br />and Flood Control District's Urban Storm Drainage Criteria Manual. Recent <br />modifications were applied to the procedure as recommended by the Urban Drainage <br />and Flood Control District. The modified CUHP equations are listed following <br />Table II. Detailed documentation of the hydrologic analysis is available at <br />the office of the Urban Drainage and Flood Control District. <br /> <br />One-hour point rainfall depths were determined from the Precipitation-Frequency <br />Atlas of the Western United States, NOAA Atlas 2, Vol. III, Colorado, 1973, <br />for the 2-, 5-, 10-, 50- and 100-hear return periods. These. val ues were used <br />to develop the two-hour design storms based upon a time distribution of rainfall <br />recommended by Urban Drainage and Flood Control District. Areal reductions of <br /> <br />B <br /> <br />lU <br /> <br /> <br />, <br />,I <br />I, <br />! I <br />, I <br />I, <br />, I <br />: i <br />, <br /> <br />I! <br /> <br />