Estimation of Discharge through a Levee Breach with Constant Cross Section

Abstract

Levee breaches have resulted in significant damage and loss of life in recent years. Although this area has been of considerable interest to researchers, procedures are not available to compute the breach outflow accurately, which are needed for flood mitigation and emergency preparedness. In this work, the outflow discharge through a levee breach with constant cross section is computed by using two different models: the first solves the one-dimensional spatially varied flow equation, and the second numerically solves the two-dimensional Saint-Venant equation. Both models are applied to a breach in rectangular and trapezoidal channels. Different cases are simulated by varying the breach width, submergence ratio, and inflow discharge. It is found that the effect of breach width on the outflow is less than that caused by the submergence ratio. Breach outflows computed by a spatially varied flow model are higher than that by the two-dimensional model. A new relationship is proposed to correct the breach outflows calculated using the one-dimensional model.