Sediment sink-source transitions in the middle and lower reaches of the Yangtze River estuary

Human activities have severely altered the Yangtze River (Changjiang) Estuary’s pattern, beach-trough shape, and delta in recent decades. Existing research has studied sediment “source–sink” relationship between mainstream estuary using gauged suspended data. This method overestimated decline concentration estuary, as riverbed scouring or deposition not filtered out amounts related to sand mining waterway dredging. study took Basin subject used spot observed runoff, sediment, topography data gathered 1980 2020 analyze trapping effect of Three Gorges Reservoir (TGR) “source-sink” transport middle-lower reaches River. The Estuary Delta is dominated by scouring, which shows an increasing trend. During operation TGR (2003–2020), load entering from decreased 68% compared amount prior commencing (1960–2002). However, studies found that there are still large bottom with movement characteristics after Project souring downstream dam increased degree recharge. 2003 2018 period 1981 2002, annual decrease 16.9%. cumulative Yichang–Datong Datong–Xuliujing 1981–2002 was 3.13×10 8 m 3 1.60×10 , respectively, 2002–2018 28.52×10 16.01×10 . concluded even if significantly TGR, gradually transformed “sink” “source” supply.