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<br />For North Fo~k Gunnison River, the starting water-surface elevations <br />were obtained from a IIEC-2 analysis performed for Gunnison River. <br /> <br />Flood profiles were drawn showing computed water-surface elevations <br />to an accuracy of 0.5 foot for floods of the selected recurrence <br />intervals (Exhioit 1). <br /> <br />The hydraulic analyses for this study were based on unobstructed <br />flOWa The flood elevations shown on the flood profiles are thus <br />considered valid only if the hydraulic structures assumed to stay <br />in place remain unobstructed, operate properly, and do not faila <br /> <br />All elevations are referenced to the National Geodetic Vertical <br />Datum of 1929 (NGVD). Elevation reference marks used in this study <br />are shown on the maps a <br /> <br />4.0 FLOOD PLAIN MANAGEMENT APPLICATIONS <br /> <br />The NFIP encourages State and local governments to adopt sound flood <br />plain management programs a Therefore, each Flood Insurance Study produces <br />maps designed to assist communities in developing flood plain management <br />measures. <br /> <br />4.1 Flood Boundaries <br /> <br />To provide a national standard without regional discrimination, <br />the 1 percent annual chance (lOa-year) flood has been adopted by <br />FEMA as the base flood for flood plain management purposes. The <br />0.2 percent annual chance (SOO-year) flood is employed to indicate <br />additional areas of flood risk in the community. For each stream <br />studied in detail, the 100- and SOO-year flood plain boundaries <br />have been delineated using the flood elevations determined at each <br />cross section a Between cross sections, the boundaries were inter- <br />polated using topographic maps at a scale of 1:4,800, with a contour <br />interval of 5 feet (Reference ll). <br /> <br />The 100- and SOO-year flood plain boundaries arc shown on the Flood <br />Boundary and Floodway ~lap (Exhibi t 2). In cases where the 100- <br />and 50 a-year flood plain boundaries are close together, only the <br />IOO-yeur floo~ plain boundilry has been shown. Small areas within <br />the [lootl bJl.uin boundaries may lie above the flood elevations but <br />cannot be shown due to limitations of the map scale and/or lack of <br />detailed topographic data. <br /> <br />Approximate flood boundaries for the downstream reach of Short <br />Draw were delineated using the maps referenced above. The remaining <br />approximate flood boundaries for Short Draw were taken from the <br />previously printed Flood Hazard Boundary Map for the Town of <br />Hotchkiss (Reference 12). <br /> <br />9 <br />