长江口年代际冲淤演变趋势预测与应对策略

受流域来水来沙条件变化及河口大型工程建设的综合影响，长江口呈现新的冲淤格局，为预测未来演变趋势，本研究基于前期研究中建立的长江口年代际冲淤演变预测模型（Delft3D），未来情景考虑不同来沙量条件和相对海平面上升速率。预测结果表明，到2035年长江口整体以冲刷为主，口内河段主槽和浅滩边缘冲刷较明显，仅高滩局部淤积；到2050年口内河段保持净冲刷状态，拦门沙地区在现状来沙量条件下略有淤积，但在极端低来沙量条件下转变为净冲刷状态，海平面上升对拦门沙地区冲刷具有一定抵消作用，但不会使冲淤状态产生本质改变。本研究分析认为，长江口局部区域未来冲淤趋势可能对河口综合治理与保护产生不利影响，针对新格局条件下的滩槽河势稳定、重要洲滩保护、重大工程安全评估、冲刷致灾研判以及海堤防护标准再评估等方面提出了对策建议，可为新时期长江口综合治理与可持续发展提供参考。

Prediction and coping strategies of decadal morphological evolution of the Changjiang Estuary

Under the combined influence of the changes of water and sediment conditions in the river basin and the construction of large scale projects in the estuary, the Changjiang Estuary presents a new pattern of erosion and deposition. In order to predict the evolution, the morphological numerical model (Delft3D) of the Changjiang Estuary established in our previous study was used, and future scenarios with different river sediment discharge and relative sea level rise were considered. The results show that the Changjiang Estuary will undergo overall erosion by 2035, especially in the main channel and at the edge of the shallow shoals. Accretion will only occur at local areas of shoals. By 2050, the inner estuary will maintain net erosion, while the mouth bar area will show slightly net accretion under the condition of current sediment discharge. However, it will convert to net scour under the condition of extremely low sediment discharge. Sea level rise will only partly offset net erosion of the mouth bar area, and will not change the accretion/erosion status. It is suggested that the future evolution in some areas of the Changjiang Estuary may have adverse effects on the comprehensive management and protection of the estuary. Therefore, countermeasures and suggestions are put forward for the channel shoal stability, protection of important tidal flats, safety assessment of major projects, assessment of scour induced disasters and reevaluation on the defense standard of coastal levee under the new pattern conditions. This research can provide reference for comprehensive control and sustainable development of the Changjiang Estuary in the new era.