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<br />SUIIIIllary and Conclusions <br /> <br />Floodplain mapping must be an approximate process if it is to be <br />economicaL Although it is tempting to calculate "exact" flood depths <br />downstream. due to failure of a dam. those depths are based on estimates and <br />assumed conditions which will almost surely not hold true at time of actual <br />failure. Recognizing this. floodplain mapping becomes the "reasonable" <br />prediction of the maximum extent of flooding. based on a set of conditions <br />which are themselves "reasonable". <br /> <br />In spite of the approximate methods used. the state engineer's office found <br />that this procedure later predicted. with reasonable accuracy. the limits of <br />flooding which actually occurred following the failure of two dams in <br />Colorado. Flood depths and aerial flood extent were determined to be <br />relatively insensitive to changes in peak failure discharge at the dam <br />site. Therefore. this procedure is of value to emergency planners and <br />government agencies as a quick and inexpensive way to estimate inundation <br />areas and flood travel times in the event of a dam failure. <br /> <br />The methods of computation of Qp and Qri have been coded into a <br />user-friendly basic language program called HAZARD2. The program allows <br />calculation of typical depths (Di) with minimal effort. following routine <br />data gathering. After gaining familiarity with these methods. the user <br />should be able to draw a typical dam failure floodplain inundation map in a <br />single day. <br /> <br />20 <br />