上海市沿海滩涂土地资源圈围与潮滩发育演变分析

上海市62%的土地是近2 000 年来长江来沙堆积而成, 尤其近50 余年来, 采用围垦-促淤-围垦等有效的拦沙造地方式, 圈围滩涂1.01×105hm2, 为缓解上海城市发展所需的土地资源紧缺、促进工农业发展和城市基本建设发挥了巨大的作用。论文将GIS 平台获取大量滩涂变化的基本数据和长期现场观测资料相结合, 总结并提出: 充分利用长江来沙资源, 采用中高潮滩种青和工程促淤拦沙圈围方法, 可加速潮滩淤涨发育和滩涂土地资源增长, 而低滩工程促淤虽然不利于潮滩地形快速恢复, 但可快速获得大片土地资源。因而, 保证了50 余年来上海市在圈围土地与基本保持沿海潮滩湿地面积总量变幅较少方面取得双赢效果。

Analysis on the Development and Evolution of Tidal Flats and Reclamation of Land Resource along Shore of Shanghai City

There was about 62% land resource of Shanghai developed as a result of the deposi-tion of sediment from the Yangtze River in the past 2 000 years.Especially in the latest 50 years,some efficient methods included Inning-Siltation Promotion-Inning, had been adopted to block upthe sediment and to create land.These reclamated land resource amounting to 1.01×105hm2 hadthe land area enlarged by 15.8% in Shanghai.Obviously, it was important that the reclamation ofland could alleviate shortage of land resource for the development of Shanghai, and promoteindustrial and agricultural development and capital construction.Based on the data of the tidalflat elevation data obgained by GIS and the long term field survey of hydrology and sediment, itwas found that the abundant sediment from the Yangtze River and its adjacent areas, thehydrologic regimes around the Yangtze River estuary were advantageous to create new landresource.Many projects, which included crop cultivation works, waterway closure works, siltationpromotion project on low tidal flats, piling up sediment from shallow seabed to the inner regionof the dam, damming under water, etc., had been successfully adopted around the shore ofShanghai.Different methods should be used at the corresponding phase in order to take a greatadvantage of the sediment supplied by the Yangtze River for promoting siltation.For example,some Inning Projects such as crop cultivation works and river branch closure works weredeveloped at the middle and high tidal flats, which could accelerate the siltation of tidal flatsand the increment of land resource.However, the projects of damming works and piling upsediment from shallow seabed to the inner region of the dam were done at the low tidal flats,which resulted in the expansion of the land resources and exposure of shallow sea topography.Itwas proved over the past 50 years that situations between reclaimed areas of land and changes ofthe areas of wetland and tidal flats could keep sustainable development.