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distinct hydrologic region of the watershed, using the values in Table <br /> 2. An overall curve number for the subwatershed was derived by <br /> calculating a subwatershed weighted average based on the relative <br /> acreage of each distinct hydrologic region. The runoff was then routed <br /> into the sediment structure (see Table 1). <br /> Precipitation and Storm Type <br /> Precipitation depths for the 10-year, and 25-year storms were developed <br /> using procedures and data published in the Soil Conservation Service <br /> publication "Procedures for Determining Peak Flows in Colorado" . A <br /> standard SCS Type II storm was utilized for each analysis. <br /> Unit Hydrograph and Surface Condition <br /> The SEDIMOT II computer program provides three unit hydrograph shapes to <br /> choose from in determining the runoff characteristics of a subwatershed. <br /> In general , the agricultural hydrograph (No. 2) was used for <br /> agricultural and undisturbed areas. The disturbed hydrograph (No. 1) <br /> was used for disturbed and reclaimed areas. <br /> Travel Time <br /> The travel times from subwatershed to structure were determined <br /> utilizing the Manning Equation. In using this method, the flow velocity <br /> is determined by flow rate and channel characteristics. The travel time <br /> will be the result of dividing the channel length by the velocity. <br /> Time of Concentration <br /> The time of concentration for each subwatershed was determined using the <br /> SCS Upland Method. In using this method, the longest flow path in each <br /> subwatershed is divided into segments of uniform flow characteristics. <br /> Within each segment, the travel time is estimated by dividing the flow <br /> length by the velocity. The time of concentration is the sum of these <br /> travel times. <br /> 4 <br />