渭干河–库车河流域及其子流域景观格局变化分析

以西北干旱区渭干河–库车河流域作为研究区，利用ArcGIS水文分析模块和DEM数据，将研究区划分为5个子流域，并选用1998年和2011年两期同时相遥感Landsat TM影像，选择支持向量机(support vector machine，SVM)方法进行土地利用分类，通过Fragstats软件计算全流域及其各个子流域的景观格局指数，分析流域景观格局变化。结果表明：①在景观类型方面，5个子流域差别很大，流域A、D中草地景观占较大比例，流域B中的其他景观类型(山地、裸地等)占较大比例，流域C、E中沙地占较大比例；②在全流域Class尺度方面，草地及耕地的平均临接度指数(CONTIG_MN)减少，林地的平均形状指数(SHAPE_MN)增加，水体与建工地的平均斑块面积(Area_MN)一增一减，盐碱地的斑块密度(PD)增加；③在子流域的landscape尺度方面，子流域B、C、E在斑块数量(NP)、景观破碎度(F)和边缘密度(ED)的增长速度明显比子流域A和D快，表明人类活动对绿洲核心地带景观格局的影响低于绿洲外围荒漠交错带。

Landscape Pattern Changes in Weigan-Kuqa River Basin and Its Sub-basin

This paper took Weigan-Kuqa River Basin as the study area in the arid northwest China. Firstly, the basin was divided into five sub-watersheds by using the ArcGIS hydrological analysis module and DEM data. Secondly, remote sensing Landsat TM images at the same phase were selected in 1998 and 2011 as the main data and land use was classified by using support vector machine (SVM) method. Thirdly, the classification results were converted into the grid format and then Fragstats software was used to calculate landscape indices of the whole basin and its five sub-watersheds, and on this basis the landscape pattern changes were analyzed. The results showed that the areas of landscape types of five sub-watersheds were very different, grassland landscape accounted for a larger proportion in the sub-watershed A and D, while mountains and barren land in sub- watershed B, and sandy landscape in the sub-watershed C and E; in the past 13years, land use type of transformation mainly occurred among the cultivated land, forest land and grassland. The number of plaques, landscape fragmentation and edge density of sub-watershed B, C, E increased faster than sub-watershed A and D, it suggested that the impact of human activities on the landscape pattern of the core oasis is lower than on the oasis-desert Ecotone.