长江河口河槽沉积物捕集对河口大型工程的响应机制

项目名称： 长江河口河槽沉积物捕集对河口大型工程的响应机制

项目编号： No.41476075

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 程和琴

作者单位： 华东师范大学

项目金额： 94万元

中文摘要： 近年来，长江河口河槽动力沉积地貌发生显著变化，使得近两千年来自然作用形成的三级分汊四口入海格局出现了显著变异，迄今研究主要集中于其与流域大坝导致来沙减少的统计关联，但有关其与流域大坝及河口围海造地、深水航道、青草沙水库等大型工程的关联机制研究尚未见报道。本项目采用历史资料对比、现场观测、基于过程的解析模型与数值模型相结合的模拟分析等方法，分析河口大型工程导致的典型河槽横向与纵向水动力、悬沙和底沙分布、床面微地貌、纵剖面与横剖面及平面形态等变异特征，重点分析北港河槽径流、潮流、浅水分潮、风应力、密度梯度和沉降延迟对河槽纵横向沉积物输运与捕集的影响机制，探讨新的流域来沙条件下北港河槽纵横向沉积物捕集对青草沙水库和深水航道工程的叠加响应机制，以此增进对流域-河口-海洋系统内自然过程与人类活动相互作用机理的了解。

中文关键词： 长江河口；河槽；沉积物捕集；大型工程；响应机制

英文摘要： For the past decades,significant changes in land boundary condition, water motion of channel occurred in response to large engineering projects as large area of land reclamation, deep waterway and freshwater reservior in the Yangtze estuary.They had led to the adjustments of sediment transport and entrapment, deposition and erosion of estuarine channels. And new change in morphology pattern composed of three bifurcations and four outlets to the sea by nature for the last 2000 years occurred. So, it is necessary to study the sediment transport and entrapment pattern of estuarine channels in response to the strong human interventions in the estuary. We propose to investigate a major problem occurring in the estuarine channels of Yangtze Estuary with the new change in development of erosion and deposition in waterways after engineering works. Specific objectives are: 1. to identify changes in hydrodynamics, suspended sediment concentration, grain size composition of the suspended sediment and bed sediment, and configurations of planar distribution, along-channel profiles and cross-channel profiles of the estuarine channels, with human interventions in the estuary; 2. to investigate the role of time-varying mixing conditions, wind, friction, nonlinear shallow water, spatial settling lag on along- and across-channel sediment entrapment with their subaqueous delta; 3. to identify and quantify the mechanisms responsible for the differences of the sediment trapping in the North Channel of the Yangtze estuary.

英文关键词： Yangtze estuary;Channel;Sediment entrapment;Large engineering projects;Response mechanism