Accretion-erosion conversion in the subaqueous Yangtze Delta in response to fluvial sediment decline

Identifying the pattern of delta morphological change under decreasing sediment flux due to dam construction is essential for sustainable management in such densely populated coastal areas. In this study, we investigated processes Yangtze mouth bar and prodelta based on bathymetric data a decadal-interannual scale (1958, 1978, 1997, 2002, 2007, 2010, 2013 2015). We found that strong accretion (205.1 Mm3 yr?1) occurred during 1958–1978, when high load (465 Mt was supplied by Yangtze. Afterwards, net accumulation rate decreased 31.9 yr?1 1978–1997 114.6 1997–2002 as result riverine loads 390 314 yr?1, respectively. Surprisingly, increased 130.8 2002–2007, though sharply 177 yr?1. This anomaly attributed training walls within area, which induced significant groyne-sheltered areas nearby regions. Along with further decrease load, entire study area converted erosion ?200.4 2007–2010 ?152.2 2010–2013. Stronger former period partly caused intensive dredging activities area. The critical discharge retain estimated be ca. 218 If deducting impacts estuarine engineering projects accretion/erosion 1997–2010, adjusted 234 combination previously reported accretion-erosion conversion elsewhere Delta, inferred most portion subaqueous has likely from response fluvial decline, showed latest among portions delta. Integrated assessment adaptive strategies are urgently required Delta survive coming erosional stage.