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<br />DIMENSIONLESS GRAPHS OF FLOODS FROM RUPTURED DAMS <br /> <br />" <br /> <br />I. INTRODUCTION <br /> <br />, <br /> <br />Dams constructed to form large water-storage reservoirs are subject <br />to failure for several reasons. According to a survey (2) foundation <br />failure and spillway inadequacy count for about two-thirds of all dam <br />failures. Though not so frequent, failures due to acts of war and <br />earthquakes may cause more serious damage since they usually occur <br />without any previous warning. <br /> <br />Experience has shown that floods resulting from the sudden collapse <br />of a dam forming a large water-storage reservoir are catastrophic. <br />Damages 3re anticipated to be higher in the future, should such a mis- <br />hap occurs. This will be due to both larger sizes of dams being built <br />and the increase in industry and population density. Human settlements <br />and the industries on which they depend usually lay in the flood plain <br />of rivers on which dams have been constructed. <br /> <br />-; <br /> <br />Knowledge of potential inundation areas can lead to the establish- <br />ment of rational real-estate zoning criteria and procedures for the <br />emergency evacuation of populated areas below the dam. In fact, this <br />is the intent of California Senate Bill 896, passed into law by the <br />California Legislature in 1972. This law requires the preparation of <br />potential flooding maps for any dam in California, the partial or total <br />failure of which would result in death or personal injury. <br /> <br />Rational and accurate methods for the preparation of such maps are, <br />as yet, unavailable for general use. Work done at the University of <br />California at Davis (3, 4, 5) led to the development of a rational com- <br />putation procedure for predicting the flood wave resulting from the <br />sudden and total failure of a dam in a prismatic river valley. <br /> <br />In this report a brief outline of the theoretical aspects of the <br />procedure is given. For details the interested reader should consult <br />the references cited above. The parameters involved and the variables <br />which express the practical significance of a dam-break flood are mainly <br />stressed. Finally, dimensionless graphs of these variables for certain <br />values, over the practical range, of the parameters are given. With <br />these graphs, a quick, approximate computation of the most important <br />aspects of a flood wave following the failure of a dam is possible. An <br />illustrative example is given. <br />