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<br />5.1 Reach Determinations <br /> <br />Reaches are defined as lengths of watercourses having relatively <br />the same flood hazard, based on the average weighted difference in <br />water-surface elevations between the 10- and lOa-year floods. <br />This difference does not have a variation greater than that indicated <br />in the following table for more than 20 percent of the reach: <br /> <br />Average Difference Between <br />10- and lOa-year Floods <br /> <br />Variation <br /> <br />Less than 2 feet <br /> <br />0.5 foot <br /> <br />Two reaches meeting the above criterion were required for the <br />flooding sources of the Town of Nunn. These included one each on <br />Spring Creek Tributary and the Western Flow Path to Spring Creek <br />Tributary. The locations of the reaches are shown on the Flood <br />Profiles (Exhibit 1). <br /> <br />5.2 Flood Hazard Factors <br /> <br />The Flood Hazard Factor (FHF) is the Federal Insurance Administration <br />device used to correlate flood information with insurance rate <br />tables. Correlations between property damage from floods and <br />their FHF are used to set actuarial insurance premium rate tables <br />based on FHFs from 005 to 200. <br /> <br />The FHF for a reach is the average weighted difference between the <br />10- and 100-year flood water-surface elevations expressed to the <br />nearest one-half foot, and shown as a three-digit code. For <br />example, if the difference between water-surface elevations of the <br />10- and 100-year floods is 0.7 foot, the FHF is 005; if the difference <br />is 1.4 feet, the FHP is 015; if the difference is 5.0 feet, the <br />FHF is 050. When the difference between the 10- and lOa-year <br />water-surface elevations is greater than 10.0 feet, accuracy for <br />the FHF is to the nearest foot. <br /> <br />5.3 Flood Insurance Zones <br /> <br />After the determination of reaches and their respective Flood <br />Hazard Factors, the entire incorporated area of the Town of Nunn <br />was divided into zones, each having a specific flood potential or <br />hazard. Each zone was assigned one of the following flood insurance <br />zone designations: <br /> <br />Zone AO: <br /> <br />Special Flood Hazard Areas inundated <br />by types of lOa-year shallow flooding <br />where depths are between 1.0 and 3.0 <br />feet; depths are shown, but no Flood <br />Hazard Factors determined. <br /> <br />9 <br />