Numerical Model for Simulating Flow and River Bed Profiles in a Natural River under Dam Failure Conditions

M.D. Saikia and A.K. Sarma (India)


Numerical Modelling, simulation, Dam break flow and Riverbed.


This paper presents a simple finite difference (FD) numerical model to simulate the unsteady water and riverbed profile due to failure of a large dam in a natural river. The mathematical model is built upon the conservative laws of shallow water hydrodynamics. Over the recent decades, there have been continuing efforts to understand dam-break hydraulics and the majority of the studies have been carried out in laboratories where channel bed is assumed to be fixed under such a highly transient flow. Dam-break hydraulics of natural rivers is indeed complicated, and involves not only water flow, but also morphological changes in the riverbed, which in turn modify the predicted flow profiles. The present investigation carried out in an Indian river clearly shows that the free surface profiles and hydrographs are greatly modified by natural river bed mobility under high super critical dam break flows, which is extremely significant for flood predictions. Hence a simple numerical model is proposed here, where all the important aspects of a real river i.e., the changes in river bed elevations and frictions, channel cross sections, sediment entrainment and depositions across the bottom river channel etc. are taken into account in contrast to most of the earlier numerical models available in literature where a fixed river bed was considered.

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