海南陵水沙坝潟湖海岸近26年地貌类型空间格局演化

THE EVOLUTION OF COASTAL GEOMORPHOLOGY PATTERN IN RECENT 26 YEARS AND ITS SPATIAL-TEMPORAL DISTRIBUTION AROUND THE TWO LAGOONAL AREAS IN LINGSHUI COUNTY, HAINAN ISLAND

通过对海南陵水县黎安、新村两个沙坝潟湖海岸地貌的野外踏勘,构建研究区地貌类型分类标准,据此采用德国智能影像分析软件eCognition提供的随机森林法模块,对1987～ 2013年26年间6期Landsat卫星遥感影进行地貌类型分类与空间分布位置图斑提取,结合ArcGIS软件据实测地形数据生成数字高程模型以及地貌类型转移矩阵数理分析技术,对研究区地貌格局演化特征及地貌类型转化趋势展开研究.结果表明,上述野外测量、随机森林遥感影像分类提取、GIS空间分析及矩阵转换数理统计等多技术方法结合用于沙坝潟湖海岸地貌长周期演化研究是可行、有效的,此方法弥补了传统采用钻孔及沉积柱状样采集分析中以点代面、难以全域覆盖的海岸带沉积地貌分析方法的不足.研究发现,近26年间,陵水双潟湖海岸地貌发生了显著变化,地貌类型转化趋势为海积平原、水下浅滩、海积阶地向养殖池及盐田转化,自然地貌间的相互转化不明显;大范围的潮滩围垦及海积平原挖掘改造,形成了一条人工地貌带,打破了原有自然地貌空间格局,改变了海积平原与水下浅滩之间的沉积动力作用方式以及物质能量交换模式,不断加强的人类活动已成为研究区海岸地貌改造的主要驱动力.

The research establishes a professional criterion to classify the coastal geomorphology patterns atter surveying at two sand-barrier lagoons, using land-cover data during 2005-2014, bathymetry data and digital terrain model data scaled as 1 ： 1000 and famated as AutoCAD DWG, in Lingshui County, Hainan Island. According to this criterion, the geomorphology patterns have been identified and classified as 6 types natural geomorphology： erosional hill tectonics, ocean sedimentary terrace, sedimentary plain, underwater shoals and marine plain, and 3 types artificial geomorphology： aque-farming pond, sahern, man-made stacking highland; then their distributing boundaries have been extracted on the 6-stage Landsat RS images from 1987 to 2013 to research the enovation characters and its shifting direction by eCognition softerware, which is an intelligent image analyzing softerware, produced in German, combined the GIS analyzing technology and the transfering matrix methods by putting multi-source data into the decisition trees of image classification to select 270 samples with 9 types and 30 samples per type and to design the classfier as 100 decision trees with 3-type decision features. The results show that the method, intergrated the surveying at field, random forest extraction on RS images, GIS 3D analyzing technology and transforing matrix statistics, is an effective and captible to research on the geographologic long-term evolution. It makes up the researching method of core and sendimentary column analyzing. The research finds out the coastal geomorphology has changed remarkably in these 26 years. The sedimentary plain, underwater bank and sedimentary terrace have been transferring to farming pond and salt field to create an artificial geomorphology band around the two lagoons after the tidal shoals reclimated and the sedimentary plains dredged, but not shifting within themselves. The original coast geomorphology patterns have been demaged; the ways of sedimentary dynamic and energy transforing have been changed thoroughly. The increasing anthropological activities are becoming a main driving force of the coastal evolution.