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<br />flood :.evels by more than 1 foot. communities must prohibit <br />development within designated floodways that would cause any <br />additional rise in the base flood elevations. The Town of Rangely <br />participates in the NFIP and has adopted the required flood plain <br />regulations. The official lOa-year flood water surface elevations <br />for Rangely are as listed in the: FIS published by t:he Federal <br />Emergency Management Agency (FEMA) in 1984 and revised in 1990 <br />(Reference 1). The designated lOa-year flood plain and floodway at <br />Rangel} is shown on FEMA's official Flood Insurance Rate Map (FIRM) <br />for thE! town (Reference :2). In 130mEl areas, all or pa.rt of the <br />designc.ted White River floodway adjacent to Rangely is located <br />outside: the Rangely corporate limits. Plate 1 shows the existing <br />loo-yec.r flood plain and floodl./ay in the st.udy area. <br /> <br />ENGINEER.ING AN1U,YSES <br /> <br />Source of Data <br /> <br />The source of the basic hydrc'logic and hydraulic information <br />used in this study was the current FIS for Rangely. This <br />information was developed by the FEMA study contractor. The <br />techni<:al backup materials frOm the FIS were obtained on microfiche <br />from F:~' s technical evaluati.on con'tractor, Michael Baker, Jr., <br />Inc. ~'opographic maps at a sCqle of :L inch equals 100 feet with a <br />2-foot contour interval were used in the FIS. Copies of this <br />mappincf were provided by the TOwn e)f Rangely. 'l'he bqsic: hydrologic: <br />and hydraulic information froIl! the FIS was not changed for this <br />study. <br /> <br />Hvdroloqic Analvsis <br /> <br />Tile peak flood discharges used in this study "ere taken <br />direct ly from the current FIS text.. 'rhe hydrology used in the FIS <br />was de'feloped from statistical ana,lysis of stream gage information <br />in the White River basin. The :LOO-'year peak discharges on the <br />White 3.iver are shown in Table L <br /> <br />Hvdraulic Analvsis - FrS StudY <br /> <br />Ttle loa-year flood water surface profiles in the FIS were <br />computed using the Corps' HEC-2 step-backwater computer program <br />(Reference 3). The HEC-2 program ca.lc:ula1:es water surface profiles <br /> <br />4 <br />