Reservoir Routing in Successive Rockfill Detention Dams using Two-Dimensional Mathematical Model for through and Overtop Flow

Rockfill dams can be considered as effective and economical tools in flood control. As such,
employing successive dams is expected to cause an effective mitigation to flood hydrograph. Since
flow in coarse media of rockfill dam is turbulent, flow analysis must be based on non-Darcy equations.
Flow effects interaction of successive rockfill dams, overtopping flow condition, which maybe
experienced by the first dam, in addition to through seepage flow lead to high complexity of
hydraulics of such dams. In this paper, by introducing the inflow hydrograph to the first reservoir,
employing a two-dimensional model for through and overtop dam flow and also employing hydrologic
reservoir routing method, it is demonstrated that obtaining the final outflow hydrograph is possible.
The mathematical model accuracy was evaluated by comparing its results to experimental data. The
model results show good agreement with this experimental data. Finally, sensitivity analysis
demonstrated that the model results is much more sensitive to the average particle size of rockfill
media compared to other parameters such as dam's length and upstream and downstream angles.