FLOOD08536 - Laserfiche WebLink

Home Browse Search

5.1 Reach Determinations Reaches are defined as sections' of flood plain that have relatively the same flood hazard, based on, the averag" weighted difference in water-surface elevations betwee~ the 10- and 100-year floods. This difference may not have a variation greater than that indicated in the following table for more than 20 percent of the reach: Average Difference Between 10- and 100-Year Flood~ Variation Less than 2 feet 2 to 7 feet 7.1 to 12 feet More than 12 feet 0,5 foot 1. 0 foot 2,0 feet 3.0 feet The locations of the reaches determined for the flooding sourceS of Fountain are shown on the Flood Profiles (Exhibit 1) and summarized in Table 3, 5,2 Flood Hazard Factors The Flood Ha?ard Factor (FHF) is used to establiGh relationships between depth and frequency of flooding in any reach, This rela- tionship is then used with depth-damage relationships for various classes of structures to establish actuarial insurance rate tables. The FHF for a reach is the averag'. weighted difference between the 10- and 100-year flood water-surface elevations rounded to the nearest one-half foot, multipli~d by 10, and shown as a three- digit code, For example, if th~ difference between water-surface elevations of the 10- and 100-year floods is 0.7 foot, the FHF is 005; if the difference is 1,4 feet, the FHF is 015; if the differ- enCe is 5,0 feet, the FHF is 050. When the difference between the 10- and 100-year flood water-surface elevations is greater than 10,0 feet, it is rounded to the, nearest whole foot. 5,3 Flood Insurance Zones Flood insllranc', zones and zone numbers are assigned based Oil the type of flood hazard and the FHr, respectively. A unique zone number is associated with each possible FHF, and varies from 1 for a FHF of 005 to a maximum of 30 for a FHF of 200 or greater, Zone A: Special Flood Hazard Areas inundated by the 100-y.>ar flood, determined by apprvximate methods; no base flood ,<'leVJlt.luns shown or FHFs determined, . 15