三峡工程对长江口南汇边滩近期演变影响初步预测

Preliminary Prediction on Recent Topography Evolution of Nanhui Tidal Flat in Yangtze Estuary due to Three Gorges Project

利用DELFT3D模型建立了长江口二维泥沙数学模型,通过实测水文泥沙资料对模型进行了验证.在此基础上,分别将上游洪、枯季流量概化和外海典型潮波组合,建立了长期冲淤模型.通过10年实测地形资料对模型进行的验证,显示该模型较好地模拟了长江口水沙运动以及长期冲淤演变过程.考虑三峡工程蓄水后上游来水来沙的变化,对近期南汇边滩的演变趋势给出预测,结果显示:三峡工程实施之后的5～20年,南汇边滩发育基本稳定,上游来沙量的减少不会造成大幅度冲刷,边滩整体继续向东南方向演变.

A 2D numerical model is built to simulate the sediment transport process in the Yangtze estuary by DELFT3D model at first.Then a morphological model is built with generalized flux process in the flood and dry seasons combined with the variation of tidal ranges at outer sea for a long-period simulation of the evolution of tidal flat.The model is validated through the surveyed data and the simulation result presents a good agreement with the real measured value.Further more,a prediction of the evolution process of Nanhui tidal flat is given under the impact of the Three Gorges Project.In general,there’s still a stable development of Nanhui tidal flat and expanding to the southeast without significant erosion caused by the reduction of water-sediment from the upstream in the next 5 to 20 years after the Three Gorge reservoir’s operation.