典型无居民海岛(担子岛)岸滩冲淤变化过程研究

A Study on the Process of Erosion and Siltation of a Typical Non-resident Island Danzi

通过统计分析、空间分析、三维分析等方法,本文重现了50年担子岛及其周围海域的冲淤变化过程。得出如下结论:(1)近50年来,研究区内淤积面积大于侵蚀面积,但侵蚀强度大于淤积强度;侵蚀区主要分布在担子岛岸滩的-2m以浅区域,侵蚀呈明显的带状分布;冲淤速率呈加剧趋势,冲淤演变呈现明显的周期变化。(2)担子岛岸滩有4条剖面的冲淤形态以"整体侵蚀后退"居多,其他剖面呈"上冲下淤"的形态,剖面冲淤转换不同的剖面水深不同,在-2m以浅的岸滩,冲淤转换一般在-1.2m左右。剖面上下部位冲淤强度的不同,造成不同剖面具有不同的冲淤平衡点。本文研究成果为控制担子岛岸滩侵蚀的速率,减缓担子岛侵蚀程度提供一定的理论依据。

The processes of erosion and siltation of an island Danzi and its surrounding sea in 50years are reproduced by means of statistical analysis,spatial analysis and three-dimensional analysis.The results are shown as follows:(1)Based on the analysis of ArcGIS software's spatial analysis module and 3D analysis module,it is found that the sedimentation area is much larger than the erosion area,and the sedimentation intensity is less than the erosion intensity in the study area.Besides,the erosion area around the Danzi Island is distributed mainly over the zonal distribution in the west side of the island within 5m depth and in the east side of the island within 10m depth.As a whole,the erosion rate has decreased;the erosion-deposition variation has shown a periodic change.There is a balance among the erosion area,the sedimentation area and the deposition area.(2)The comparison of the typical profile of the data showed that the upper parts of profile eroded,and that the lower parts silted in the coast of the Danzi Island.Different erosion-deposition profiles have different erosion-deposition of conversion depth.The erosion-deposition conversion often occurred on 1.2m of the profile within the 2m depth. The difference of erosive intensity and deposition intensity resulted in the variation of erosion-deposition conversion in the profile.Those results are helpful for the control and reduction of the rate and degree of erosion on the shore of the shoulder island.