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<br />Single Event Computation <br /> <br />DAMCAL has the capability to calculate damages which would occur for several <br /> <br /> <br />specified frequency flood events while the program is aggregating damages <br /> <br />to the index location. The capability is extremely useful because it elim- <br /> <br /> <br />inates errors which can occur when a user attempta to interpolate between <br /> <br />elevation-damage values. <br /> <br />To illustrate the potential problem, Table 4-5 shows damages for a particu- <br />lar land use category at several elevations. If the 50-year flood event <br />for the index location is 637.5 feet, a user might interpolate linearly <br />between the elevations of 637 and 638 feet in estimating the damages at <br />$37,000. What is not known is whether the value of $62,000 for an elevation <br />of 638 feet represents a large number of grid cells with a tenth of a foot <br />of flooding or if a small number of cells were experiencing greater depths <br />of flooding. In the former case an elevation of 637.5 could result in a <br />relatively insignificant increase in damages from that shown at an elevation <br />of 637 feet ($12,000). In the latter case the $37,000 estimate could be a <br />reasonable approximation of the damages due to a 50-year flood event. <br /> <br />TABLE 4-5 <br /> <br />AGGREGATED ELEVATION-DAMAGE VALUES FOR A <br />PARTICULAR LAND USE CATEGORY <br /> <br />I <br />~ <br />~ <br /> <br />Elevation <br /> <br />$ <br />Damages <br />(x 103) <br /> <br />640 <br />639 <br />638 <br />637 <br />636 <br />635 <br /> <br />120 <br />65 <br />62 <br />12 <br />10 <br />o <br /> <br />4-28 <br />