Two-dimensional multi-rockfill detention dam flow model in reservoir routing

Rockfill dams are considered to be effective and economical tools in flood control. In particular, employing successive dams is expected to cause effective mitigation to flood hydrographs. Since the flow in the coarse media of a rockfill dam is turbulent, flow analysis must be based on the non-Darcy flow equations. Flow interaction effects of successive rockfill dams, the overtopping flow condition (which may be experienced by the first dam) and flow through successive dams leads to very complex flow hydraulics. This paper presents a new methodology to investigate the hydraulics of successive dams within a flood routing context. By introducing the inflow hydrograph to the first reservoir, employing a two-dimensional model for flow through and over the dam, and employing a hydrologic reservoir routing method, the final outflow hydrograph was obtained. The model results show good agreement with experimental data. Sensitivity analysis demonstrated that the model results are more sensitive to the average particle size of rockfill media than other parameters such as dam length or upstream or downstream angles.