The steepness and confinement of the channel right beneath the Crowley Lake dam results a translation of outflow hydrograph in time. Therefore, the dambreak analysis is only conducted on the neighborhood near City of Bishop where the gradient of topography is mild.

K634 Modeling Results and Discussion

Using the K634 model for computing the twodimensional flow was attempted by means of the onedimensional nodal spacing (figure 8). Cross sections were obtained by field survey, and the elevation data were used to construct nodal point flowwidth 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 K634 flood plain limits. To model the flow breakout, 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 floodway section in order to approximately conserve the onedimensional momentum equations. Consequently, fictitious channel sides are included in the K634 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 6feet, yet the

