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<br />o <br /> <br />Times of Concentration (TC) <br />Source: Urban Hydrology for Small Water sheds, TR 55 dated June, <br />1986, worksheet 3 <br />Hydraulic analysis <br />Source: Flowmaster PC Program for Open Channels and Field Surveys <br />Rating Curves <br />Manning's "N" Roughness Values <br />Average Velocity <br />Cross sectional conveyance <br />o Curve Numbers (CN) for the Sub-Basin <br />Source: See Table 2 <br />o Frequency rainfall values <br />Source: NOAA Atlas 2" Precipitation-Frequency Atlas of the Western <br />United States Volume III - Colorado <br /> <br />o <br /> <br />. <br /> <br />o Sub-basin characteristics <br /> <br />Source: <br /> <br />See Exhibit 1 <br /> <br />. <br /> <br />These values which were used for the analysis are presented on the basin schematic <br />for the Sulphur Creek Basin as shown on Exhibit No.2. <br /> <br />The input data and summary output Tahles for the TR-20 computer run for the 100- <br />year flood event are presented in Exhibit No.3. The TR-20 runs for the 10-, 25-, and 50- <br />year are presented in the Technical Addendum for the Sulphur Creek Basin Hydrology <br />Analysis dated March, 1992. <br /> <br />FINDINGS OF STUDY <br /> <br />A detailed hydrologic investigation was performed for the Sulphur Creek Basin. The <br />investigation analyzed past flood events and their runoff characteristics; reviewed existing <br />flood-related studies and projects for the basin; evaluated the basin hydrologic parameters <br />. 8 <br />