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<br />--1 <br />( <br />\ <br />I <br />( <br />i <br />\ <br />i <br />( <br />( <br />I, <br />i <br />i <br />( <br />( <br />i <br />f <br />i <br />I <br />i <br />( <br />i <br />i <br />i <br />I <br /> <br />i <br />I <br />\ <br />I <br />, <br />r <br />, <br />1 <br />,. <br />i <br />I <br />i <br />, <br />I <br />i <br />f <br />( <br />i <br />j <br />,. <br />i <br />i <br />f <br />f <br />( <br />~ <br />! <br />f <br />( <br />i <br />I <br />~ <br /> <br />contents damage value was multiplied by each of these ratios and added to the appropriate <br />percent damage to structure value to obtain a combined value which represented the total <br />percent damage (contents and structure) as a percent of the structure value. For example, an <br />expected annual damage value of 2.0 means that total damage to structure and contents is <br />expected to be 2 percent of the structure value or $400 per year for a $20,000 structure. <br /> <br />Management Adjustments <br />Five types of management adjustments were analyzed, <br /> <br />(1) Raising a structure 3 feet and 5 feet. <br /> <br />(2) Protecting a structure to 3 feet and 5 feet above the first floor. <br /> <br />(3) Removing structure and contents from the flood plain. <br /> <br />Damage reduced for each adjustment was computed by subtracting from the total damage <br />the damage remaining with the structure either raised or protected. Raising a structure was <br />intended to simulate the potential damage reduction when an existing or new structure without <br />basement is raised. Protecting a structure was intended to simulate conditions when openings <br />are closed to prevent water from entering or when a structure is protected by a wall or levee. <br /> <br />No damage was assumed to occur to either superstructure or basement until the protection <br />level was exceeded, then damage was assumed to be that indicated by the depth-damage <br />functions. <br /> <br />Method of Analysis <br />The parameters and respective variables used in the analysis are summarized in Table A-2. <br />The method of computation for expected annual flood damage is illustrated in Figure A-4. To <br />simulate different locations of a structure in a flood plain the elevation to which different <br />exceedance frequency events would rise was set at the first floor of a structure. The 2 yr, 5 yr, 10 <br />yr, 15 yr, 20 yr, 25 yr, 30 yr, 50 yr and 100 yr events were each in turn assumed to be at the first <br />floor elevation. For each event located at the first floor a series of frequency curves were used to <br />compute expected damage. This series included three frequency curves for each FHF from 1.0 <br />to 20.0 in increments of 1.0. One curve for each skew D, I and M. On the depth-damage side <br />expected annual damage was computed using depth-damage relationships for each type <br />structure and each location of contents. These were then combined using four ratios of value of <br />contents to value of structure. The sensitivity of three sets of depth-damage data were <br />analyzed - 1970 FIA Data, 1974 FIA Pata, and Huntington District Data. One Set - the 1970 FIA <br />Data - were used to evaluate economic feasibility. Five flood plain management adjustments <br />were analyzed for each parameter and variable described above. These included raising the first <br />floor elevation 3 feet and 5 feet, protecting the structure to 3 feet and 5 feet above the first floor, <br />and removing structure and contents from the flood plain. Computations for the analyses were <br />performed using the Hydrologic Engineering Center's computer program "Expected Annual <br />Flood Damage Computations" (3). <br /> <br />A-4 <br />