近年来横沙东滩围垦区前沿地形演化规律及驱动因素分析

河口大型滩涂演化关系到航运通畅、生态保护以及近岸工程的安全性，也是地貌学和工程界关注的热点。本文选择横沙东滩围垦区前沿5 m等深线包络区域作为研究区，2011–2017年间利用单波束测深系统对研究区进行持续性高精度监测，并结合近年来流域来沙、河口工程的建设和极端气候变化等影响因素分析其冲淤格局。结果表明:(1)近年来横沙东滩基本呈中间淤涨、周围冲刷的态势，整体由工程前“长大不长高”转化为工程后的“长高不长大”的演化格局；(2)海域来沙是此区域淤积的主要物源，研究区两侧涨落潮流路分异引起的环流是导致此区域淤积的主要动力；(3)深水航道堤坝工程、横沙东滩围垦工程等是导致研究区中间淤涨的原因；(4)人类活动可以直接影响滩槽的演化格局，工程建设的固定制约了河槽和滩涂的摆动，但也加剧了研究区局部的冲刷，未来应注意其内部串沟的发展，防止其连通威胁堤坝和滩涂的稳定。

Analysis of the evolution process and the driving factors in the coast of the reclamation area of East Hengsha Shoal during recent years

The evolution of estuarine large-scale tidal flat is highly related to costal engineerings, e.g., navigation, ecological and et al. Thus it is one of the key topics in the studies of estuarine geomorphology as well as engineering. The patterns of riverbed evolution and the driven mechanisms were analyzed based on the high resolution monitor results of topography with a single-beam bathymetry system in the coast of the reclamation area of East Hengsha Shoal during 2011 to 2017. Meanwhile, the sediment discharge, the estuarine engineering project, the extreme climate event and et al., are also included. The results are summarized into four aspects. (1) The East Hengsha shoal showed a trend of siltation in middle area and a trend of scouring in surrounding area. The whole evolution pattern experienced from “growing wide-not-high” before the project to “growing high-not-wide” after the project. (2) The sediment source of the siltation is marine dominanted, while the dynamics source of that is driven by the circulation induced from the divergence of flood and ebb current. (3) The groin of the Deep Water Project and the reclamation in the East Hengsha shoal are the main reasons of intermediate deposition in the study area. (4) The evolution of shoal-channel pattern is sensitive to anthropogenic activity. The embankment project along the shore line holds on the swing of river channel, but aggravates the erosion of local banks. In the future, more attention should be paid to the evolution of the internal ditches to prevent their connectivity, which may cause serious problem on the stability of the embankment and the beach.