三角洲前缘岸滩对河流来沙减少响应的敏感性探讨——以长江口门区崇明岛向海侧岸滩为例

利用ArcGIS对1977—2004年不同时段的长江口崇明岛向海侧水下地形测量资料进行处理,并结合该区的潮滩历史遥感图片、现场高程测量以及同期大通站输沙率资料,探讨三角洲前缘岸滩冲淤演变对河流来沙减少响应的敏感性。结果表明:研究区岸滩的淤涨速率总体上在年代以上时间尺度随着长江来沙减少而下降,但由于局部滩—槽演变和海洋动力条件的影响,某些年代内和某些部位可能出现相反的趋势,使岸滩演变对河流来沙减少的响应变得复杂化。在此基础上预测今后几十年研究区的冲淤趋势。

Sensibility of Delta Forward Coastal Response to Decrease in Riverine Sediment Supply:A Case Study from the Seaward Coast of the Chongming Island in the Changjiang River Delta

Based on analysis of topographic data surveyed between 1977 and 2004 in the subaqueous delta on the seaward side of the Chongming Island in the Changjiang River Delta with ArcGIS software,and data of remote sensing and measurement of elevation in the intertidal area within the same region,this paper deals with the sensibility of delta response to decrease in riverine sediment supply.The results show that as a whole the progradation rate of the study area went down with the decrease of sediment supply from the Changjiang River in time scales longer than a decade.However,the response was complicated because of the marine hydrodynamics and evolution of local shoal-channel systems,and reverse trends could be found in some shorter periods and subareas.On the basis of these findings,the future evolution of the study area was forecasted for the coming decades.