FLOOD02195 - Laserfiche WebLink

Home Browse Search

. Hvdraulic Analvsis Hydraulic methods used for the approximate floodplain delineations shown on the Fort Morgan FIRM are not available or have not been documented by FEMA. An approximate lOO-year floodplain delineation for areas outside of Fort Morgan can be obtained by referencing the Morgan County Flood Insurance Study or the 1977 Corps of Engineers study, which relied on approximate hydraulic techniques. For future studies, an approximate lOO-year flood elevation at a particular location on the river may be obtained by using the appropriate lOO-year peak flow value (Table l) in conjunction with an acceptable hydraulic analysis. Hydraulic analyses for determining lOO-year water surface elevations for approximate floodplains may be performed using FEMA's Quick-2 computer program, the Corps of Engineers' HEC-2 computer program, or other acceptable hydraulic methods. Channel and floodplain cross-sections may be obtained from detailed topographic mapping or from field surveys. FloodDlain MaDDinl! The existing Flood Insurance Rate Map for Fort Morgan does not accurately depict areas subject to lOO-year flooding. The map also does not show the correct and current limits of the corporate boundary of the City. The floodplain mapping has been revised by the CWCB using approximate floodplain mapping techniques. The revisions are based on conversations with the Public Works Director, field investigations, review of detailed topographic mapping for Fort Morgan, and information contained in the 1977 Corps of Engineers study. The revised floodplain map is . included in the appendix of this FIR. FLOODPLAIN MANAGEMENT Local Ordinance Requirements Communities which manage their floodplains in Colorado do so most often through the local regulatory process, This requires a community to adopt an ordinance or regulation which sets forth the performance standards by which development will occur in identified flood hazard areas. Nationwide and in Colorado, regulations are enforced within the area of the lOO-year floodplain. The basic requirement of these regulations is that new development and significant improvement of existing development cannot occur in the lOO-year floodplain without a floodplain development permit being obtained. Obtaining such a permit requires compliance with engineering standards. In communities like Fort Morgan that have approximate floodplain information, the engineering standards have been more general. Structures must be built with materials and techniques that "minimize flood damages". For communities that have detailed floodplain informatian, more specific regulations would apply, The use of engineering techniques presented in this report can help the City to better regulate its approximate floodplain areas, . 4