MATHEMATICAL MODELLING OF TRANSIENT BED PROFILES IN NONUNIFORM SEDIMENTS

Abstract

The computation of transient bed profiles of natural canals and streams which are not in equilibrium is of great importance to hydraulic engineers. In the present study computer programmes have been developed for obtaining the bed profiles of a non- equilibrium stream using two transport laws, viz. that of Engelund and Hansen and that of Samaga et, al. Data of a certain reach of the Upper Ganga Canal were used to check the results from the mathematical model. It was noticed that inclusion of the storage term in the continuity equation for sediment did not have any effect on the bed profile within the range of data considered. The bed profiles computed using Samaga et. al. equation, which takes sediment :nonuniformity into account for sediment transport, gave better results as compared to the Engelund and Hansen Equation which does not take-into account the sediment, nonuniformity. The mixing layer concept has been used for computation of variation in size distribution of bed material in space and time.