杭州湾庵东浅滩地貌演变规律

杭州湾南岸庵东浅潍的地貌演变具有长周期、多年周期和年周期变化。浅滩舌部的进退、摆动,以及滩面高程和潮沟系统的变动,是周期性演变的主要表现。地貌过程各控制因素通过杭州湾湾口和湾顶两个高混浊带提供的输沙通道,以及浅滩输沙结构的调整,间接或直接影响浅滩的演变,出现各个层次的动力-地貌响应关系。其中长周期和多年周期响应与长江及钱塘江两河口系统的调整有关,枯水条件下河口系统上移,庵东浅滩供沙不足;丰水条件下,两输沙通道会于庵东浅滩,促进了浅滩的淤涨。在年周期的小尺度演变中,波浪条件具有重要的影响。

Dynamical deyelopment of the Andong tidal flat in Hangzhou Bay,China

Cyclic fluctuations of geomorphologic processes with the periods of 1 year, 10'years, 102years and 103years are found from historic records about Andong Tidal Flat, a point-bar-like tidal flat situated along the south shore of Hangzhou Bay.These are readily reflected by orientation of its northern tip and type of its tidal channel systems, as well as those indicated in detail by topographic maps.Two sediment transport passages to the Andong Tidal Flat, developed along the two turbid belts of the bay respectively, and the sediment transport system inside the tidal flat, are presented as the links between geomorphologic processes of the tidal flat and its dynamical factors. Such links occurs in the levels with different space- time scales. It is responded to the adjustment estuarine systems both of Changjiang River and Qiantang River for the periods longer than 10 years.The Andong Tidal Flat is suffered in short supply of sediment when both estuarine systems shift upstream in low run-off period. And it enjoys abundant support when the passages concentrate more sediment here in high run-off period. But the little scale evolution such as those in a period of 1 year seems to be dominated by the effect of waves.