Suspended sediments in the estuary play an important role in regulating the erosion-accretion and shaping the geomorphological patterns. Yet, it can be strongly impacted by the human activities. Constructions of basin and estuarine engineering in the Yangtze River Estuary (YRE), including constructions of Three Gorges Dam (TGD) further upstream of the Yangtze River and Deep Waterway Project (DWP) in the estuary, have greatly modified the distribution of estuarine suspended sediment concentration (SSC). In this study, we retrieved the surface water SSC in the YRE from a total of 149 Landsat-TM/ETM+/OLI images (from 1984 to 2020) and 515 GOCI images (from 2011 to 2020) to obtain its long-term dynamics. The results indicate that the SSC estimation model performed well with a mean absolute percentage error of 12.83% and a root mean square error of 0.027 g/L. The SSC in the YRE demonstrated an overall declining pattern over the past 37 years, particularly during the flood season, which was related to the decrease in the sediment discharge of Yangtze River. The SSC in different sub-regions across the entire YRE responded differently to the reduced sediment discharge caused by the impoundment of the TGD. The SSC in the inner estuary responded promptly with a 40.3% decline noted immediately after the impoundment of the TGD, whereas hysteresis of SSC changes was found in the estuarine turbidity maximum zone (TMZ) and have begun to decline by 20.0–30.0% in the recent 5 years. Constructions of local estuarine engineering, such as the DWP also exert important controls on the estuarine SSC dynamics by blocking the lateral transport of suspended sediments between the shoal and the river channel. Our results highlight the strong influence of engineering constructions on the SSC dynamics in the world large river-influenced estuaries.

河口悬浮沉积物对调节侵蚀-增生和塑造地貌格局具有重要作用。然而，它可能受到人类活动的强烈影响。长江口流域河口工程建设，包括长江上游三峡大坝（TGD）和河口深水航道工程（DWP）的建设，极大地改变了河口悬浮泥沙的分布浓度 (SSC)。在这项研究中，我们从总共 149 张 Landsat-TM/ETM+/OLI 图像（1984 年至 2020 年）和 515 张 GOCI 图像（2011 年至 2020 年）中检索了 YRE 地表水 SSC 以获得其长期动态。结果表明，SSC估计模型表现良好，平均绝对百分比误差为12.83%，均方根误差为0。027 克/升。长江流域SSC在过去37年总体呈下降趋势，尤其是汛期，这与长江排沙量减少有关。整个长江流域不同子区域的 SSC 对 TGD 蓄水造成的沉积物排放减少的反应不同。内河口的 SSC 反应迅速，在 TGD 蓄水后立即下降 40.3%，而在河口最大浊度区 (TMZ) 中发现 SSC 变化滞后，并在河口开始下降 20.0-30.0%最近5年。局部河口工程的建设，如 DWP，也通过阻止浅滩和河道之间悬浮沉积物的横向输送，对河口 SSC 动力学施加重要控制。