Agenda - 11-27-1995 - C-1-b - Laserfiche WebLink

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03i vegetation. However, riparian ecosystems have been classified into "zones" which refer to the probability of annual flooding. Combined, these "zones" make up the 100-ywar f oodp"n or area expected to flood at least once in a 100-year period. The 100-year floodplain can be further divided into two areas on the basis of hazard potential. The floodway is the area within and adjacent to the stream banks required to discharge the 100-year flood without raising the water surface elevation more than one foot above base flood level at any point. Obstacles in the floodway can disrupt this function, increasing the potential for flood damage. The floodway fringe is the area bordering the floodway which will be inundated during a flood and hold the floodwaters until they can be carried away in the floodway channel. In 1980,the Federal Emergency Management Agency JUAA)prepared a Flood Insurance Stuff for Orange County.While the purpose of the study was to aid in the implementation of the National Flood Insurance Act of 1968 and local flood damage prevention programs, the study defined the boundaries of 100-year floodplains along major streams and rivers in the county. Orange County applied and was admitted to the federal Flood Insurance Program and subsequently adopted a Flood Damage Prevention Ordinance on March 2, 1981. The ordinance constitutes a major regulatory tool affecting the use of land constrained by flood hazards. Alluvial Soils. Not all of the 100-year floodplains in the county have been defined by FEMA. However, the Soil Survey of Orange County- N.C. contains information through which to identify soils subject to flooding. Alluvial soils are located along stream corridors and have resulted from repeated deposition by flood waters over time. They indicate not only past, but potential future, flooding. These soil types and their characteristics are listed on the following table. ALLUVIAL & HYDRIC SOILS Floodint Water Table Soil Type Frequency Duration Depth feet Kind Altavista Occasional Very brief 1.5 to 2.5 Apparent once or less in 2 years less than 2 days) (a thick zone Chewacla Common 0.5 to 1.5 of free water in Frequent Brief the soil) Congaree more than once in 2 ears 2 to 7'da s 2.5 to 4.0 Source: Soil Survey of Qrangg County.N.C.,U.S.D.A. Soil Conservation Service, 1977. The 100-year floodplains and alluvial soils in Orange County are shown on the Floodplain Map. Since floodplain areas are more extensive and overlay many alluvial soils,these features have been combined into a composite map. Wetlands Wetlands comprise one of the Earth's most productive natural ecosystems and have a set of common natural functions that make them valuable resources. These resource values can be summarized as follows: