Reservoirs are essential for hydropower production, water supply, flood protection, fishing, navigation and tourism. However, they are subjected to sedimentation on the medium and long term, which affects their functions. Therefore, there is a growing need to mitigate this problem. Sediment Bypass Tunnels (SBTs) are effective measures against reservoir sedimentation by diverting sediment-​laden flows past the dam. Their efficiency is expressed by the ratio of bypassed sediment volume to inflow sediment volume. Due to the high cost of construction and maintenance, SBTs are rarely deployed, leading to a lack of experiences, data and knowledge, particularly on the interrelation between reservoir and SBT operations and their impacts on SBT efficiency. In this project, we aim at a better understanding of the nexus between reservoir sedimentation and management and determining optimal operating conditions. To this end, we conduct field measurements and investigate the hydraulics, sediment transport and deposition processes in the Solis reservoir equipped with a SBT. Based on the field data, sediment balances are established and used to analyze the reservoir sedimentation processes. The findings of this study will provide a basis for improving sediment management at reservoirs and contribute to the optimization of reservoir and SBT operations, sustainable use of hydropower.

Velocity and bathymetry measurements using ADCP at the Solis reservoir (Photo: VAW)