流域和河口高强度人类活动对崇明岛滩涂资源变化过程的影响

入海河口形成的冲积沙岛滩涂因陆海水沙变异而出现快速冲淤已成为当前河口城市发展关注的焦点。崇明岛为我国最大的入海河口冲积沙岛,其滩涂给上海提供极其重要的空间资源,但因流域和河口高强度人类活动可能导致滩涂出现新的变化状态。据此,通过长达30多年的环岛实测地形资料,基于ArcGIS平台摸清崇明岛滩涂资源变化过程及主控要素。研究结论主要包括：（1）崇明岛各段滩涂冲淤过程复杂多变,冲淤交替频繁;但总体上北部、南部和东滩滩涂面积均为正增长,分别增加170 km²、8 km²和51 km²。（2）促淤圈围工程导致北支泥沙量增多加速河槽萎缩淤积,是北部滩涂增长的主因。（3）新桥水道北移且有所淤浅导致南部滩涂面积淤涨,而东滩快速围垦及岸堤向海推进引起东滩滩涂面积扩大。

Study on the influence of intensive human activities on the variation process of tidal flat resources in Chongming Island

The rapid erosion and deposition of tidal flat in alluvial island in estuaries due to the variations of land-sea sediments discharge has become the focus of urban development. Chongming Island, the largest alluvial island in China, has become an extremely valuable reserve land resource in Shanghai. However, the tidal resource in this island possibly presented new variation due to intensive human activities in drainage basins and estuaries. Accordingly, based on topographic data and measured bathymetric data around Chongming Island from 1984 to 2016, we illustrated the variation process of tidal flats in the study area through ArcGIS analysis and mathematical statistical analysis, and discussed the main factors influencing the geomorphic evolution of tidal flats. The results mainly include: (1) The process of erosion and accretion in each section of tidal flat around Chongming Island was complicated and varied. Totally, during the past three decades, the areas of the northern, southern and eastern beaches increased by 170 km², 8 km² and 51 km², respectively. (2) Variation of the northern tidal flat was affected by land reclamation, which led to the shrinkage of the north branch and promoted the continuous growth of the tidal flat. (3) The deposition of Xinqiao channel and its northward movement to the island directly caused the expansion of the southern tidal flat. The eastern tidal flat was dominated by frequent reclamation projects. Owing to the continuous outward movement of the embankment, the tidal flat expanded greatly in the past decades.