近十年来长江口九段沙周边地貌演变GIS分析

The Study of the Yangtze Delta Jiuduansha's Surrounding Landform Evolution by GIS in the Recent Decade

长江口深水航道工程改变了长江口自然环境,导致周边水下地貌形态发生明显的变化。本文选取长江口九段沙周边浅滩区域作为研究区,搜集不同年份的海图资料,利用GIS技术进行地貌演变空间分析。分析发现:自2001年一期工程完工以来,九段沙周边浅滩总体处于稳定状态,冲淤空间分布特征明显;沿着南导堤堤坝泥沙淤积明显,导致南导堤北侧丁坝内形成淤积带,九段沙尾部沿着堤坝形成淤积带;江亚南沙下沙阻挡作用,使得上游来水在沙头处分流,在两股水流的作用下,九段沙西南侧分别形成两条平行的淤积带和冲刷带。

The Yangtze Estuary Deep -water Channel Project has changed the natural environment of the Yangtze Delta , leading to the obvious change of the surrounding underwater topography .This article selected the shallow areas near The Yangtze estuary Jiudu-ansha as the study areas .It collected the chart data in different years , and used the GIS technology for spatial analysis of the geomor-phologic evolution .We can conclude from the analysis that since the completion of the deepwater channel project in 2001 , the Jiudu-ansha shallows are overall in a steady state .The sediment accumulation is obvious along the south dike dam , forming the Deposit belt in the north side of the south dike Groyne and the deposit belt along the dam at the end of Jiuduansha .The water from upstream dis-tributes at the head of sediment under the blocking of River of Nansha .Under the effect of two flows , the southwest side of Jiuduansha has respectively formed two parallel deposit belt and wash zone .