Venting of turbidity currents approaching a rectangular opening on a horizontal bed

Reservoir sedimentation is a worldwide problem hampering the sustainable use of reservoirs and the sediment balance of impacted rivers. Various techniques are applied for sediment mitigation. However, as turbidity currents are a major source of sediments in reservoirs, venting them through outlets reduces sedimentation. The sediment release efficiency associated with venting turbidity currents on a horizontal bed is experimentally investigated in this paper. The outflow discharge and duration of venting are the main parameters assessed. Venting efficiency is studied based on two different concepts: (1) a global venting efficiency comparing inflow and outflow sediment fluxes during the total venting operation and (2) a local venting efficiency comparing masses starting at the arrival of the turbidity current to the outlet and taking into account deposited sediment masses. An efficiency indicator accounting for water losses is also introduced. Results can be used to improve the efficiency of venting by employing adequate outlet discharges.