Comparison between shallow water and Boussinesq models for predicting cascading dam-break flows

This paper investigates the flood wave propagation between two reservoirs, linked by an open channel with a constant gradient. The dam-break flows are caused by the collapse of the upstream dam. The performance of two mathematical models is evaluated: one is based on the standard shallow water equations, and the other is based on the shallow water Boussinesq equations. Both models are solved numerically herein using a total variation diminishing Lax–Wendroff scheme. Computed results are systematically compared, with the laboratory measurements used as references. In particular, this paper extensively examines the run-up of the flood wave on the downstream dam wall, and its dependence on the bed slope and the initial water depths in the upstream and downstream reservoirs. The findings are useful for analyzing the risk of cascading dam failures. Overall, the Boussinesq model is found to give better agreement with the measurements, as it is capable of capturing the short undulations at the front of the flood bore. The superior performance of the Boussinesq model is more significant at larger downstream water depths.