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<br />. <br /> <br />. <br /> <br />. <br /> <br />Hvdraulic Analvsis <br />Hydraulic methods used for the approximate floodplain delineations shown on the Gilpin County <br />FHBM panels are not available or have not been documented by FEMA. For future studies, an <br />approximate IOO-year flood elevation at a particular location on the river may be obtained by using <br />the IOO-year peak flow value (as provided in this report) in conjunction with an acceptable <br />hydraulic analysis. Hydraulic analyses for determining IOO-year water surface elevations for <br />approximate floodplains may be perfonned using FEMA's Quick-2 computer program, the Corps <br />of Engineers' HEC-2 computer program, Flowmaster, or other acceptable hydraulic methods. <br />Channel and floodplain cross-sections may be obtained from detailed topographic mapping or from <br />field surveys. Cross-sections obtained from USGS quadrangle maps are not advised. <br /> <br />Floodplain Mappinl! <br />The existing Flood Hazard Boundary Map for Gilpin County depicts areas subject to IOO-year <br />flooding based on approximate technical methods. The map does not show flood profiles, base <br />flood elevations, or sufficient detail in order for County officials, engineers, developers, and land <br />owners to make floodplain determinations with any certainty. The Colorado Water Conservation <br />Board can be contacted to request technical assistance for approximate floodplain analyses as <br />needed. <br /> <br />FLOODPLAIN MANAGEMENT <br /> <br />Local Ordinance Requirements <br />Communities that manage their floodplains in Colorado do so most often through the local <br />regulatory process. This requires a community to adopt an ordinance or regulation, which sets forth <br />the performance standards by which development will occur in identified flood hazard areas. <br />Nationwide and in Colorado, regulations are enforced within the area of the IOO-year floodplain. <br /> <br />The basic requirement of these regulations 'is that new development and significant improvement of <br />existing development cannot occur in the IOO-year floodplain without a floodplain development <br />permit being obtained. Obtaining such a permit requires compliance with engineering standards. In <br />communities like Gilpin County that have approximate floodplain information, the engineering <br />standards have been more general. Structures must be built with materials and techniques that <br />"minimize flood damages". For communities that have detailed floodplain information, more <br />specific regulations would apply. The use of engineering techniques presented in this report can <br />help the County to better regulate its approximate floodplain areas. <br /> <br />Flood Insurance <br />Flood insurance is made available to owners and occupants of floodprone property through the <br />federal govemment's National Flood Insurance Program (NFIP). The federally backed flood <br />insurance is available to anyone in any community that participates in the NFIP. At the time of this <br />publication, Gilpin County is currently participating in the NFIP, and officially joined the regular <br />program of the NFIP on March I, 1986. Communities become participants by adopting floodplain <br />regulations, adopting an NFIP map (if one exists) and agreeing to cooperate with the federal <br />5 <br />