Abstract:

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 km2 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 middle mountain and low mountain effected by the development of karst landform and water erosion， the geomorphological process of middle part is relatively strong and characterized by the alternative distribution of middle hills and high hills. The landform classification is consistent with the actual landscape distribution. And there is a significant correlation between the distribution of city and morphology. This method of autoclassification of landforms could provide references for resource development， soil and water loss， land use research in the Three Gorges Reservoir Area