The steepness and confinement of the channel right beneath the Crowley Lake dam results a translation of outflow hydrograph in time. Therefore, the dam-break analysis is only conducted on the neighborhood near City of Bishop where the gradient of topography is mild.
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K-634 Modeling Results and Discussion
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Using the K-634 model for computing the two-dimensional flow was attempted by means of the one-dimensional nodal spacing (figure 8). Cross sections were obtained by field survey, and the elevation data were used to construct nodal point flow-width versus stage diagrams. A constant Manning's roughness coefficient of 0.04 was assumed for study purposes. The assumed dam failure reached a peak flow rate of 420,000 cfs within one hour, and returned to zero flow 9.67 hours later. Figure 9 depicts the K-634 flood plain limits. To model the flow break-out, a slight gradient was assumed for the topography perpendicular to the main channel. The motivation for such a lateral gradient is to limit the channel flood-way section in order to approximately conserve the one-dimensional momentum equations. Consequently, fictitious channel sides are included in the K-634 model study which results in an artificial confinement of the flows. Hence, a narrower flood plain is delineated in figure 9 where the flood flows are falsely retained within a hypothetical channel confine. An examination of the flood depths given in figure 11 indicates that at the widest flood plain expanse of figure 9, the flood depth is about 6-feet, yet the
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