Author(s): Mohammad. E. Meshkati Shahmirzadi; Tetsuya Sumi; Sameh A. Kantoush
Linked Author(s): Tetsuya Sumi
Keywords: Flood Mitigation Dam; Hydraulic jump; Energy dissipation; Transparent dam; Flow field and sediment depositions
Abstract: Flood mitigation dams (FMDs) in the normal condition permits the flow pass through the bottom outlet unobstructed. Meanwhile, a large percentage of river inflow can be temporarily stored within the reservoir during the flood events. Stilling basin, thus, is vital to dissipate the energy of outflow from FMDs to protect downstream reaches from unfavorable degradation and side bank erosions. However, the function of stilling basin in FMD is not only to dissipate the excess energy of the outflow, but also to let the sediment and fish pass through the structure unopposed. This paper introduces a new concept and design criteria to enhance the environmentally transparency of FMDs by In-ground Stilling Basin (ISB). The main objectives of the paper are: i) to clarify the flow field characteristics within the ISB and in the downstream; ii) to investigate the bed topography changes and assess flushing efficiency of flow and sediment through the ISB; and iii) to evaluate the interaction between sediment deposition and flow flied characteristics. To fulfill these objectives, the velocity profile, the water level fluctuations and flow visualizations have been monitored.