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<br />subject to ice jams and those which experience uncertain flow path flooding (alluvial fans, aggrading <br />and degrading channels, and migrating channels). <br /> <br />· There needs to be full integration of geologic hazards into the floodplain mapping process, <br />because land subsidence, landslides, and mudflows can exacerbate flood hazards. <br /> <br />Maps and Structural Projects <br /> <br />Flood Insurance Rate Maps are used to plan future development and help advise individuals about <br />flood risks, The current practice of modifying a Flood Insurance Rate Map to reflect the presence of <br />a levee, dam, channel, or other structural measure may foster a false sense of security to those living <br />in the area protected by these structures, City officials often forget that floodplains protected by dams <br />are still at risk from flooding, Dam- and levee-failure zones-areas that might be inundated if the <br />flood control structure is breached or overtopped-are rarely mapped. This omission also promotes <br />constricting the channel, the loss of riparian zones, destroying floodplain characteristics, and <br />ultimately leading to higher flood stages (and potentially increased damage) downstream, Options <br />need to be evaluated that reflect how Flood Insurance Rate Maps and resulting management tools <br />could be modified, <br /> <br />· Flood hazard maps should be developed that depict all related hazards, for example, the failure <br />zones of all dams, levees, and floodwalls, Not only is this identification important for notification <br />and warning purposes, but also development in these zones should have added flood protection, <br />and flood insurance should be mandatory, with rates based on the residual risk. <br /> <br />· All development proposals should provide added flood protection for facilities that are built in <br />dam and levee failure zones, <br /> <br />· Properties in failure zones that are bought with federally backed mortgages should continue to <br />be subject to the mandatory flood insurance purchase requirement, with rates based on the <br />residual risk. <br /> <br />ENGINEERING <br /> <br />Hydrologic and Hydraulic Models <br /> <br />· More accurate and flexible engineering models must be developed and incorporated that reflect <br />unsteady state flow conditions, levee breaches, split flows, and hazards of unstable land forms and <br />debris flows. The existence of the Corps of Engineers Hydrologic Engineering Center as a <br />national leader and single point of contact has been beneficial to the advancement of this <br />technology, <br /> <br />Broader Federal Design Manuals <br /> <br />Engineers and planners continue to rely heavily on the federal government's design manuals, At <br />present these manuals do not address bioengineering or other alternatives to structural design. An <br />exception is the new multi-agency River Restoration Manual. <br /> <br />Association of State Floodplain Managers <br /> <br />-26- <br /> <br />National Flood Programs in Review 2000 <br />