Dam-Break Flood in a Prismatic Dry Channel

A mathematical model is presented for the prediction of the flood wave resulting from the instantaneous break of a dam in a prismatic, dry channel of general parabolic cross section. It consists of the numerical integration of the characteristic equations over the irregular grid formed by the characteristic lines using a predictor-corrector scheme. The solution is advanced towards the wave front by a gradual refinement of the characteristics net for reasons of accuracy and economy. Finally, the solution is extended over a short region to the wave tip, which is characterized by zero depth, using a simplified form of the momentum equation resulting from physical considerations in the wave-tip region. Computed results are compared with experimental and theoretical results obtained by others. Corroboration with experimental results is generally good. The solution can be advanced in time until the negative wave propagating into the still water reaches the upstream end of the reservoir.