Lidi Shi1,*, Binliang Lin1, Jian Sun1, Khosro Morovati1
E-mail: shild18@mails.tsinghua.edu.cn
1. State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, 100084, PR China
Confluences are common components of all riverine systems. Existing studies mostly focus on the specific confluence hydrodynamics influenced by confluence planform geometry, momentum ratio and bed concordance/discordance, but there are few research on the density flow, which could alter the fluvial processes that affect mixing within confluences, especially combined with the impacts of reservoir regulation. In this study, we investigate the hydro-thermodynamic processes at a major confluence in the Yangtze River using a 3D numerical model. The results show that reservoir regulation alters flow patterns in the confluence zone significantly in both horizontal and vertical planes. The density difference leads to changes in the hydro-thermodynamic processes, especially in combination with the reservoir regulation. More importantly, it is found that the combined effect of reservoir regulation and thermal buoyancy alters the flow structure considerably in the confluence zone, and modifies the water transport mode in the mainstream.