长江河口拦门沙河段滩涂演化特征及驱动机制

Evolution of tidal flat in the bar area of the Yangtze Estuary and their driving factors

利用长江河口实测1958-2013年水下地形数据,基于ArcGIS技术和DSAS软件分析了拦门沙河段滩涂演化特征,在此基础上结合河口重大工程建设、流域来沙状态对滩涂资源的变化机制进行分析。研究结果表明:(1)1958-2013年,长江河口滩涂资源总量略有下降,但最近十年趋于稳定,维持在2 350km2左右。(2)长江河口潮滩-5m等深线以下已经出现侵蚀,垂向侵蚀速率为达7.3cm/a;(3)近10多年流域来沙剧烈下降对潮下带0^-5m区域的滩涂资源淤涨产生了显著负面影响,而河口重大工程建设则是近年来0m以上滩涂逆势增长的主要驱动因素。

Bathymetric data surveyed from 1958 to 2013 were analyzed using ArcGIS and DSAS software to investi- gate the evolution of the tidal flats in the bar area of the Yangtze Estuary. And driving factors such as the declined riverine sediment supply and the major engineering works constructed in the Yangtze Estuary were discussed in this study. The results demonstrated that： （1） the amount of tidal flat resources has experienced slight decrease since 1958; but it comes to be stable, with amount of 2 350 km2 in recent decade. （2） the area deeper than 5 m has be- gun to experience erosion since 1997, and the averaged vertical erosion rate was 7.3 cm/a. （3） the dramatic sedi- ment decline from Yangtze River in recent decade has brought negative impact on the progradation of the tidal flat deeper than 0 m. Nevertheless, the area shallower than 0 m was continued to accretion due to the influence of the engineering works in the estuary.