1D modelling of dam-break surges with floating debris

Abstract

To predict flood and debris flow dynamics a numerical model, based on 1D De Saint Venant (SV) equations, was developed. The McCormack–Jameson shock-capturing scheme was employed for the solution of the equations, written in a conservative-law form. This technique was applied to determine both the propagation and the profile of a two-phase debris flow resulting from the instantaneous and complete collapse of a storage dam. To validate the model, comparisons were made between its predictions and laboratory measurements of flows of water and homogeneous granular mixtures in a uniform geometry flume that can reproduce dam-break waves. Agreements between computational and experimental results were considered very satisfactory for mature (non-stratified) debris flows, which cover most real cases. To better predict immature (stratified) flows, the model should be improved in order to feature, in a more realistic way, the distribution of the particle sizes within the mixture. On the whole, the model proposed can easily be extended to channels with arbitrary cross sections for debris flow routing, as well as for solving different problems of unsteady flow in open channels by incorporating the appropriate initial and boundary conditions. The great advantages of the technique developed are that it is based on the strong shock-capturing ability of the McCormack–Jameson numerical scheme and has a simple application of the resulting algorithm when considering 1D debris flow phenomena.