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<br /> <br />Development at any place <br />in the watershed can re- <br />duce the permeahility of <br />the soil, thus increasing <br />runoff and flood levels. <br />Th,:, increase in flood <br />levels can then endanger <br />properties that may have <br />previous(v been above the <br />base flood elevation. <br /> <br /> <br />18 <br /> <br /> <br />r <br /> <br />US Army Corps of Eni'incers <br /> <br />system. Even if the site itself is not likely to be floode(~ <br />dt.''Velopment on it can have a major influence on flooding <br />and flood damage at other locations. Any modification <br />that inCre;l'ieS runoff or disrupts natural protective sys- <br />tems will increa'\e flooding at other locations, whether it <br />be in the downstream portions of the watershed or in- <br />land portions of the coastal area. <br />Alteration of the naturallxliance on a single site may <br />only have a small impact. But the cumulative impact of <br />many individual sites or of large-scale developments, a., is <br />the rule more than the exception, can be ma'isive. This is <br />amply illustrated by the flash flood in Kansas City in 1977 <br />Due to an unusually heavy thunderstorm, the rapid <br />accumulation of runoff in a highly developed urban area <br />created a six-feet,high wall of water in an otherwise dry <br />creek bed. The result was over $30 million in damages <br />and 24 lives lost <br /> <br />De'Velopment Pressures <br />Human occupation of flood-prone areas brings with it <br />inevitable losses of life and property and the disruption <br />of commerce and services. Despite a long history of such <br />losses, we continue to build and rebuild in hazardous <br />locations. Ideally, this should not happen; however, the <br />forces of development are as inevitable as the storms that <br />produce flooding in the first place. In many ca<;es people <br />are unawdre of the hazard,,; of a given site or the effects of <br />development on tl(x)ding at other sites. In yet other cases <br />the risKo; are known, but locational advamages seem to <br />override the hazard. Or the existing infnL<;tructure in a <br />flood-prone area is considered too enormous a capital <br />investment to abandon. Too often, the speculative pres- <br />sures of development override common sense. <br />Flooding is a normal occurrence, with the degree of <br />