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<br />FEMA Ve~sus Local Community Roles in F~n Development <br /> <br />FEMA cu~~ently ~equi~es that communities join the Flood <br />Insu~ance P~og~am, that no new st~uctu~es be const~ucted <br />within the floodway, and that all new st~uctu~es built <br />within the flood plain be elevated above the base flood <br />elevation. Local communities a~e othe~wise f~ee to use <br />zoning, st~uctu~al tools, o~ non-st~uctural tools to <br />minimize flood damages. If structu~al measu~es le.g., dams. <br />channels, levees) are implemented, the delineated flood <br />plain and floodway (FIS mapping) a~e alte~ed to ~eflect the <br />new flood limits. Non-st~uctu~al measu~es le.g., zoning, <br />elevation, floodp~oofing) do not alte~ the flood pl~in. <br /> <br />On alluvial fans with no ent~enched channels the flood <br />plain, based on the 'OO-yea~ flood limits, could occupy most <br />of t~e fan su~face. The floodway could be defined as the <br />enti~e channeli~ed hyd~aulic ~one. Unde~ existing FEMA <br />statutes, all new st~uctu~es on such a fan must be elevated. <br />while no st~uctu~es can be built in the channelized zone. <br /> <br />Existing statutes p~ovide limited guidance ~ega~ding cont~ol <br />of sediment deposition, scou~, and othe~ ha~a~ds on alluvial <br />fans. FEMA ~equi~es that any obst~uctions to flow in the <br />flood plain not inc~ease flood ~elated ha~a~ds. including <br />inundation and scou~. On alluvial fans. this ~equi~es that <br />structu~es built upstream of existing developments not <br />inc~ease the velocity. depth, o~ scou~ potential of flood <br />flows. All managem~nt tools must be integ~ated with <br />downst~eam developments. The bu~den of p~cof that flood <br />management tools meet FEMA ~equi~enents has. in the past, <br />fallen on local communities. <br /> <br />Whole-fan Ve~sus Local Tools <br /> <br />While FEMA has not <br /> <br />~equi~ed <br /> <br />that whole-fan <br /> <br />tools <br /> <br />be <br /> <br />94 <br />