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<br />a~e likely ~o be ineffective due to the fo~ce <br /> <br /> <br />of the channelized flow. Consequently, <br /> <br /> <br />development of this zone should be avolded <br /> <br /> <br />unless complete cont~ol of floodwate~s, using <br /> <br /> <br />deb~is basins and/o~ ch~nnels, is assu~ed. <br /> <br />. In the b~ilided flow ~ the hyd~aulic <br />conditions a~e e~~atic and may alte~nate <br />between channelized an~ b~aided conditions. <br />Depths of flow and velocities a~e lowe~; othe~ <br />haza~ds a~e less seve~e. Local management <br />tools can be used, p~ovided that they a~e <br />adequately a~mo~ed. Use of st~eets o~ channels <br />fo~ conveyance may be effective. p~ovided that <br />upst~eam dive~sion dikes ensu~e that the <br />e~~atic flow paths a~e always di~ected into the <br />channels. Elevation on fill should be avoided <br />~nless flow is confined to a~mo~ed st~eets o~ <br />channels. <br /> <br />. The sheet flow zone is cha~acte~ized by shallow <br />flooding; although velocities a~e lowe~, <br />supe~c~itical flow conditions a~e common. <br />Local management tools, including elev~tion on <br />a~mo~ed fill, can be used. Flood behavio~ c~n <br />be substantially alte~ed by development and by <br />management tools in the up-fan hyd~aulic zones. <br />Hence. up-fan development must be coo~dinated <br />with development in this zone. <br /> <br />Effect ~ EKistinq ~ P~o;ected Development Density <br />EKisting and p~ojected development densities have a majo~ <br />impact on the app~op~iateness and feasibility of management <br />tools. Substantial eKisting development compounds the <br />difficulty, cost. and effectiveness of implementing most <br />tools. <br /> <br />90 <br />