Laserfiche WebLink
<br />Approximate elevations were determinAd by applying the regional <br />discharge-drainage area information to the Animas River and Cunningham <br />Creek in the areas selected for approximate study. Elevations were <br />determined using this dischargG and a typical valley cross section <br />as determined from a U.S. Geological Survey topographic map (Refer- <br />ence 13). <br /> <br />All elevations are referenced to the National Geodetic Vertical <br />Datum of 1929 (NGVD). Elevation reference marks used in the study <br />are shown on the maps. <br /> <br />4.0 FLOOD PLAIN MANAGEMENT APPLICATIONS <br /> <br />A prime purpose of the National Flood Insurance Program is to encourage <br />State and local governments to adopt sound flood plain management pro- <br />grams. Each Flood Insurance Study, therefore, includes a flood boundary <br />map designed to assist communities in developing sound flood plain manage- <br />ment measures. <br /> <br />4.1 Flood Boundaries <br /> <br />In order to provide a national C3tandard without regional discrimina- <br />tion, the 100-year flood has been adopted by the Federal Insurance <br />Administration as the base flood for purposes of flood plain manage- <br />ment measures. The SOG-year flood is employed to indicate additional <br />areas of flood risk in the community. For each stream studied in <br />detail, the boundaries of the 100- and SOO-year floods have been <br />delineated using the flood elevations determined at each cross <br />section; between cross sections, the boundaries were interpolated <br />using topographic maps at scale of 1:2400, with a contour interval <br />of 2 feet (Reference 14). <br /> <br />The shallow flooding on Mineral Creek west of the Denver and Rio <br />Grande Western Railroad was delineated using topographic maps at a <br />scale of 1:2400, with a contour interval of 2 feet (Reference 14). <br /> <br />On Cement Creek, shallow flooding occurs on the adjacent properties. <br />The lOa-year flood boundaries were delineated using the flood eleva- <br />tions computed with the flow staying in the creek only. The boun- <br />daries of shallow flooding due to the IOO-year flood are not shown <br />because they are confined within the SOQ-year flood boundaries. The <br />SOO-year flood boundaries upstream from the u.s. Highway 110 bridge <br />were determined using the computed flood elevations. Downstream <br />from the bridge, where shallow flooding occurs, the boundaries were <br />delineated by considering possible spread of floodwaters. <br /> <br />On Mineral Creek downstream from U.S. Highway 550, where overflow <br />occurs, the SOO-year flood boundaries were determined, with considera- <br />tions of possible flood route. <br /> <br />11 <br />