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<br />to land use 1 (future condition). In the aggregation process associated <br /> <br />with future development, the base condition composite damage function would <br /> <br /> <br />be used for the original four grid cells shown, whereas, a modified composite <br /> <br />damage function would be used for the converted grid cell. <br /> <br />It is possible in a single computer run to uniformly flood proof as many <br /> <br />land use categories as desired and to have a unique flood proofing level <br /> <br />for each category. <br /> <br />Flood Proofing to a Specified Protection Level. Flood proofing selected <br /> <br /> <br />land uses to a specified protection level (within a given damage reach) re- <br /> <br />quires the computation of the depth of flooding in each grid cell resulting <br /> <br />from a flood event equivalent to the protection level specified. If a cell <br /> <br />is inundated by that flood event, it is then flood proofed to an elevation <br /> <br /> <br />corresponding to the depth of flooding. In general, flood proofing a damage <br /> <br />reach to a particular frequency protection level would require some grid <br /> <br /> <br />cells of a given land use category to be protected several feet, while others <br /> <br />may need only the basements flood proofed or no protection at all (see Fig- <br /> <br />ure 4-7). <br /> <br />~ <br /> <br />Construction of elevation-damage functions for this option is based on <br /> <br /> <br />rating curve data (discharge versus stage or elevation) at the index loca- <br /> <br />tions. From a particular rating curve the elevation of the water surface <br /> <br /> <br />at the index location which corresponds to the desired protection level <br /> <br /> <br />is determined and input into the DAMCAL program. The corresponding protec- <br /> <br />tion level (elevation) is then computed for each grid cell using the reference <br /> <br />flood, since changes in water surface elevation at the cell are consiatent <br /> <br /> <br />with changes in water surface elevation at the index location. (It should <br /> <br />be remembered that damage reaches were defined based on essentially parallel <br /> <br />water surface profiles). The flooded grid cells are subsequently flood <br /> <br /> <br />proofed to protect against the specified event. <br /> <br />The computations are performed as follows: the reference flood elevation <br /> <br />is subtracted from tbe target protection elevation at the index location <br /> <br />4-19 <br />