近30年长江北支口门附近的冲淤演变及其对人类活动的响应

Morphological evolution and its response to human activities at the mouth area of the North Branch,Yangtze estuary,during the recent three decades

根据1981—2012年长江北支口门附近的海图以及遥感数据,利用Arc GIS技术进行计算分析,以了解近30年该区域的冲淤演变特点和规律,从而丰富海岸带陆海相互作用的研究案例.结果表明:1981—1997年潮间带围垦面积为13 km2,水域平均淤积速率为1.4 cm/a;1997—2012年,潮间带围垦面积为163 km2,水域平均冲刷速率为-7.1 cm/a.31年间,口门内、外水域的淤积速率分别为0.77 cm/a和-1.97 cm/a.结论包括:近30年研究区的冲淤演变受到北支衰亡趋势、口内滩涂促淤围垦和长江流域建坝等引起的入海泥沙通量下降的影响,其中人类活动是近15年研究区冲淤演变的控制性因子.

In order to enrich the knowledge of land-ocean interaction,this paper examined the recent accretion and erosion at the mouth area of the North Branch,the Yangtze Estuary,based on bathymetric and remote sensing data and using Arc GIS techniques. The results show that：（ 1） from 1981 to1997,13 km2 of intertidal area was reclaimed; an average accretion rate of 1. 4 cm / yr was observed in the subtidal area.（ 2） from 1997 to 2012,163 km2 of intertidal zone was embanked,and an average erosion rate of-7. 1 cm / a was found in the subtidal area.（ 3） Between 1981 and 2012,an average accretion rate of 0. 77 cm / a was found in the inner portion,and an average erosion rate of-1. 97 cm /a occurred in the outer portion. We concluded that the morphological evolution in the study area was controlled by three factors—the silting trend of the North Branch,the intertidal accretion-promoting projects,and dam construction within the Yangtze watersheds. During the recent 15 years,human activities were the dominant factor.