چکيده

One of the most important applications of rockfill dams is to control flood by reducing the peak discharge of inflow. It is of great importance to study how much of the inflow to the rockfill dam reservoir is transferred to the downstream under unsteady flow conditions. In the present study, flood routing in dual detention rockfill dams was studied using four experimental data samples, linear Muskingum method, and particle swarm optimization (PSO) algorithm and the effect of rockfill dam length, distance between two dams, and aggregate size was studied on the K coefficient of linear Muskingum method. The results showed that the mean relative error (MRE) of the four experiments used in the present study were equal to 4.9, 3.4, 4.35 and 3.55%, respectively, and the relative error of the peak discharge (DPO) of the mentioned experiments were calculated as 1.58, 0.47, 2.86 and 1.78%, respectively, which indicates the high accuracy of the linear Muskingum method in estimating the outflow hydrograph. The results also showed that, by increasing the distance between the inflow and outflow hydrographs, the K coefficient increased and by increasing the aggregates size, the flow velocity increased and consequently, the K coefficient decreased.