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

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.