The application of baffle block in mitigating TDGS of dams with different discharge patterns

Abstract

Total dissolved gas supersaturation (TDGS) caused by high-dam discharge leads to gas-bubble trauma or even death in fish and has become an active research area because of global concern regarding this issue. It is important to use engineering measures to reduce the TDGS level to protect the fish habitat and water environment. As there are different mechanisms for TDGS generation by discharge, the application of mitigation measures needs to be investigated. In this study, three dams in which bottom flow, surface flow and trajectory jet used for energy dissipation were simulated to analyze the characteristics of TDGS generation and distribution. The simulated results show that the generation and distribution of TDGS is affected by bubble-water mass transfer. Consequently, a mitigation measure in which baffle blocks installed downstream of the spillway was proposed to change transport bubbles to low-pressure regions. The simulated results showed this engineering measure reduced TDGS by 5.2% and 13.1% for dams with bottom flow and trajectory jet, respectively. This study serves as a reference for the characteristics of TDGS generation and the design of TDGS mitigation measures.