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<br />elevation just prior to failure. The important energy losses occur as <br /> <br />the flood wave moves downstream and include friction losses, bend <br /> <br />losses, expansion and contraction losses and others. <br /> <br />In addition to energy considerations, the volume of water which <br /> <br />is available in Cranks Creek Reservoir to sustain the flood wave must <br /> <br />be considered. Figure 3 shows the capacity of each reservoir as a <br /> <br />function of its elevation. The increase in elevation of Martins Fork <br /> <br />Reservoir due to storing the volume of water in the flood wave could <br /> <br />possibly be greater than the energy consideration. This would depend <br />on rate of energy dissipation and the rate of outflow from Martins <br />Fork. It is also possible that the maximum force could result from <br />some combination of the energy and volume considerations. Therefore, <br />a time history of the flood wave motion is required to adequately analyze <br />the problem. <br />Methods which are cOlllDlonly used in flood routing, such as the <br />modified Puls, Muskingum, Tatum, and straddle-stagger, permit direct <br />consideration of volumes only. Indirectly, energy considerations are <br /> <br />inferred by calibrating these methods to some experienced event. Such <br /> <br /> <br />methods are inadequate for routing the dam-break flood--at least in the <br /> <br /> <br />early stages, because energy plays such a dominant role in the movement. <br /> <br /> <br />Therefore, one must resort to a solution of the basic equations of <br /> <br />unsteady flow to consider both continuity and momentum. <br /> <br />4 <br />