Landward shifts of the maximum accretion zone in the tidal reach of the Changjiang estuary following construction of the Three Gorges Dam

• Datong-Xuliujing Reach (DXR) exhibits a distinct accretion zone in 1992–2002 and 2008–2013. River-tide dynamics dominate the pattern of morphological variations along channel. These exhibit Gaussian depositional phase. The maximum sedimentation DXR shifted ~100 km landwards after TGD regulation. Impacts from anthropogenic activities have substantially modified geomorphology most world’s large rivers. While many studies focused on fluvially-dominated estuarine/delta segments these rivers, their tidal reaches that links river to estuarine delta is much less extensively documented. Yet, key transition zones, however, directly affect transfer water sediment sea, significant influence environment. Here, we analyze variation (DXR), reach Changjiang River, following closure operation Three Gorges Dam, using unique dataset combining surveys 1992, 2002, 2008 2013. results demonstrate three different development phases. When supply high (at 3.18 × 10 8 t/y), experienced deposition (1992–2002) with located middle portions reach. Thereafter (2002–2008) channel underwent major period erosion coincident substantial decline fluvial (to 1.72 t/y). More recently (i.e., during 2008–2013), entire deposition, but shifting around 100 landward (compared its position 1992–2002), while riverine was further reduced 1.30 t/y. Our analytical modelling reveals damped discharge, induced by Dam regulation, relatively strong level fluctuation forcing wet season, are responsible for upstream shift zone. In addition, local caused sand mining dredging generate spatial nonuniformity observed patterns DXR. Such knowledge vital importance sustainable management alluvial rivers as they respond natural effects.