Investigating the effect of dam body length on the distribution of sediment concentration in the Rockfill dam reservoir

Building homogeneous rock-fill dams is certainly one of the most effective methods of controlling floods. In flood situations, the in-flow to these dams typically contains a considerable amount of sediments. This underscores the need to study the flow behavior and sediment concentrations so that one could identify the amount of passed and trapped sediments, and decide on their management. Thus, first, on the basis of numerical solution of Saint-Venant equations, the flow characteristics (e.g. depth and velocity) were calculated, using finite volume method, with a completely implicit approach, and then the concentration of the sediments at different points of the reservoir were determined, using discretization of the convection diffusion equation based on upwind hybrid. For this purpose, first mathematical model of mentioned equations prepared in Matlab and then in order to evaluate the performance of this model used the results of conducted experiments in the hydraulic laboratory of Agriculture faculty of Bu-Ali Sina University of Hamadan on the Rockfill dams. On the basis of the comparison drawn between the data yielded by measurement of sediment concentration and the calculations conducted in eight sections and three layers of 5, 10 and 15cm high in the reservoir of rock-fill dams, mean value of the relative error of sediment concentration was found to be 5.1, 7.1 and 8.2 percent, indicating a good correlation between the output of mathematical simulator and measured sediments in the experimental model. Results also revealed a decrease in the relative error of the simulator with an increase in the diameter of aggregates used in the body of dam due to the better structure of hypotheses of one-dimensional flow.