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<br />C-ID <br /> <br /> <br />Appendix 3-A: Suggested Development Guidelines for Various Hydraulic Zones on the Fan. <br /> <br />The following applications of management tools were recommended by Floodplain <br />Management Tools for Alluvial Fans, a report prepared for the Federal Emergency <br />Management Agency (1981). The recommendations apply to each hydraulic zone on the <br />fan and for the placement of single structures: <br /> <br />Channelized Zone <br />Development prohibited unless whole-fan measures are implemented. <br /> <br />Braided Zone <br />Basements and mobile homes prohibited. <br /> <br />Streets aligned and designed to convey entire flood flow. <br /> <br />Use of local dikes to direct flows into streets. <br /> <br />Use of drop structures between homes built on high slopes to prevent excessive <br />erosion. <br /> <br />All management tools must be coordinated with tools in existing developments. <br /> <br />Whole-fan management tools can be used instead of the above provisions, <br /> <br />Shallow Flooding Zone <br />Elevation of structures on piles or armored fill. <br /> <br />Street orientation to maximize flood conveyance. <br /> <br />If up-fan subdivisions use depressed streets or channels to convey floods, these <br />tools must be continued down to the fan toe. <br /> <br />Use of drop structures between homes built on high slopes. <br /> <br />Whole-fan management tools can be used instead of the above provisions. <br /> <br />Placement of Single Structures <br />In undeveloped areas, place structures on armored fill or use local dikes provided <br />that no added flood damage to other structures results. <br /> <br />In developed areas, local dikes, channels and armored fill must tie in with existing <br />flood control tools, <br /> <br />Elevation on piles should be used if above criteria cannot be met. <br /> <br />No single placement should be allowed in the channelized zone. <br />