Test and Improvement of 1D Routing Algorithms for Dam-Break Floods

Classical models for one-dimensional (1D) flood routing calculations were tested in a synthetic benchmark and in a real dam break case, the observed flashy hydrographs on the Doce River after the collapse of the Fundao Tailings Dam in Brazil. The application of existing methods presented unsatisfactory results, with an error in prediction of the peak discharge up to -18%, and differences in timing to peak up to 4 h. An improved 1D flood routing approach is proposed, solving the dynamic equation into an equivalent linear diffusive wave format. This modified method reformulates the hydraulic diffusion coefficient in terms of the Froude number and flood wave celerity, which are parameters more coherent with the linear model assumption and provide more realistic flood wave attenuation. The solution given by this approach can be carried out using the Crank Nicolson or QUICKEST schemes. The relative percent difference (RPD) in predicted peak discharge is reduced to less than -0.1%.