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<br />Guidelines and Specifications for Flood Hazard Mapping Partners [April 2003] <br /> <br />Highway Administration (FHW A) WSPRO computer model (USGS and FHW A, 1999). <br />Regardless of the hydraulic model used, the Mapping Partner shall follow modeling techniques <br />specified in the most recent version of the appropriate user's manual. <br /> <br />In addition, the Mapping Partner using HEC-RAS shall provide input and output files in the <br />HEC-RAS native file format, although the Mapping Partner may use a variety of shell programs <br />to conduct analyses. The numerical models currently accepted by FEMA for use in the NFIP are <br />listed on the FEMA Flood Hazard Mapping Web site (http://www.fema.gov/fhm/en modl.shtm). <br /> <br />A wide variety of automation tools have been developed to facilitate hydraulic modeling. These <br />products range from simple graphical user interfaces that help input model parameters to highly <br />advanced GIS-based tools that contain state-of-the-art software and modeling approaches with <br />fully integrated data processing, graphics, and visualization capabilities. The tools have been <br />organized into three categories based on their relationship to accepted FEMA models. The <br />following is the policy for their acceptance for use in FEMA's flood hazard mapping program. <br /> <br />. Category 1 Tools: These simple tools can be either pre-processing or post-processing <br />independent modules. They function in conjunction with, but separately from, the <br />executable file of a computer model that is on the FEMA accepted models list. These <br />tools are considered acceptable because they are not computer models themselves. <br /> <br />. Category 2 Tools: These software tools are computer models that perform modeling <br />routines that emulate a model on the FEMA accepted model list; however, their source <br />code has been rewritten to perform these tasks, instead of using the accepted model's <br />source code. Category 2 software tools must be reviewed and placed on the accepted <br />models list. <br /> <br />. Category 3 Tools: These software tools use new hydraulic modeling methods and/or <br />models not currently on the FEMA accepted models list. They may add pre- or post- <br />processing functions similar to the other categories of tools as well. Because these are <br />new computer models, Category 3 software tools must be reviewed and placed on the <br />accepted models list. <br /> <br />C.3.2.2 FJoodway Determination <br /> <br />[February 2002] <br /> <br />A regulatory floodway is defined as the channel of a river or other watercourse and the adjacent <br />land areas that must be reserved in order to discharge the 1-percent-annual-chance flood without <br />cumulatively increasing the water-surface elevation by more than a designated height. The NFIP <br />regulations designate a height of 1.0 foot. Regulatory floodways are developed as unobstructed <br />waterways to convey floodwaters. The community is responsible for maintaining the <br />conveyance of flooding sources to mitigate flood hazards. <br /> <br />If the State in which the Flood Map Project is being performed has established more stringent <br />regulations for the maximum allowable rise in water-surface elevations, through legally <br />enforceable statutes, then these regulations shall take precedence over the NFIP regulatory <br />standard. In the case of streams that form the boundary between two or more States, the 1.0-foot <br />maximum allowable rise criterion shall be used unless the States have previously agreed on a <br /> <br />C-18 <br /> <br />Section C.3 <br />