河口冲淤对围垦的响应

Response of estuarine erosion and deposition to reclamation in estuary

为了研究椒江河口地形对毗邻海域连续多段大面积滩涂围垦(即集群围垦)的响应,利用二维潮流非均匀沙数学模型,预测椒江河口现状岸线下及规划围垦工程后的床面冲淤.结果显示:现状岸线下未来河口河道大部分区域发生冲刷,口外拦门沙有少量淤积;规划围垦工程后河口河道及口外拦门沙淤积,河口延伸段冲刷;与各围垦工程单独作用的叠加效果相比,集群围垦联合作用下的冲淤幅度更大,即存在非线性效应,应在围垦规划时予以重视;河口水动力随毗邻海域围垦面积的增大而减弱,水流挟沙能力随之下降,因而河口河道及口外拦门沙的淤积厚度随围垦面积的增大而增大.

Large scale and multi-stage reclamation （i. e. cluster reclamation） of tidal flat was planned and performed near the Jiaojiang Estuary. A series of numerical simulations were carried out by using a 2D mathematical model for tidal flow and nonuniform sediment transport in order to investigate the response of seabed erosion and deposition to cluster reclamation in Jiaojiang Estuary. According to the results, ero-sion occurred in most part of estuarine channel while a small amount of deposition occurred in mouth-bar region in the situation of present coastline. When the planned reclamation is imposed, a serious deposition occurs in estuarine channel and mouth-bar region while the new extend part of estuary caused by reclama-tion is eroded. Compared with the combined effect of each single reclamation on erosion and deposition, the effect of the whole cluster reclamation is larger, that is to say, there is a nonlinear effect. Special at-tention for the nonlinear effect should be paid to the effect of cluster reclamation on seabed evolution. With the increase in the area of reclamation, the hydrodynamics of estuarine channel and mouth-bar region weakens and therefore sediment transport capacity decreases, then the thickness of deposition increases in these areas.