传统地貌类型划分时多是基于单一或固定的地形因子进行分析,存在一定的片面性和主观性.以90 m分辨率三峡库区SRTM DEM数据为基础,利用均值变点分析法确定了三峡库区地势起伏度的最佳统计单元面积为2.34 km2;并采用相关矩阵法和雪氏熵值法获取三峡库区地貌类型划分的最佳因子组合为高程、起伏度、坡度、全累计变率、坡度变率、高程变异系数;同时借鉴遥感图像自动分类原理中的ISODATA非监督分类功能完成了三峡库区8种地貌类型的自动划分.分类结果与三峡库区实际地貌类型相符,对三峡库区资源开发、水土流失、土地利用的研究具有参考价值.
It is important for the research of landscape as it is one of the most basic elements of the natural environment and its control over the differentiation of natural environment,There are still certain one-sidedness and subjectivity for the traditional landscape classification due to the use of single or fixed terrain factor analysis.To overcome this problem,we carried out an auto-classification of landform test in the Three Gorges Reservoir Area.This region is lying on the lower section of the upper reaches of the Yangtze River.There are serious soil erosion and heavy landslide,collapse and debris flow here.Firstly,we took a statistics on the relief amplitude values in different analyzing grids (3 × 3,5 × 5 39 × 39,41 × 41) based on SRTM DEM using Arcgis9.3,then the method of mean of change-point analysis was used to extract the optimum statistical unit of the relief amplitude.The calculated result is that the optimal analyzing grid is 17 × 17,about 2.34 km2 for the Three Gorges Reservoir Area,but this result may be lower than the true value.Through the comparison and analysis with former study,it proved that the optimal area of analyzing grid decreased with the increase of DEM resolution.Secondly,The method of correlation matrix and Sheffield entropy were used to get the optimal topography feature which contain the elevation,range,slope,accumulation curvature,slope of slope,height variation coefficient.Whether this optimal topography feature could be used elsewhere still need to be studied.Lastly,a multispectral remote sensing image was constructed with the red band of elevation,green band of range and blue band of slope.ISODATA unsupervised classification was applied to get the distribution of 8 kinds of geomorphic types in this region automatically.The western and the eastern region is given priority to with plains and low hills.The Dabashan mountain is under the intense river cut in northeast area with mainly mountain landscape,the Wushan and Daloushan are featured with