基于GIS的典型岩溶流域土地利用变化分析——以云南省小江流域为例

Land Use Change in Typical Karst Watershed Using GIS-based Analysis——Taking Xiaojiang Watershed of Yun'nan Province as an Example

在GIS支持下,利用云南小江流域两期土地利用图形数据叠加分析,得到土地利用变化图和土地利用转移矩阵。结果发现,1982—2003年全流域610.12km2的土地利用面积发生变化,占流域总面积的59%。土地利用的类型主要是由未利用地向耕地和林地以及林地向耕地的转化,流域综合土地利用变化动态度达2.95%。土地利用空间格局的基本构型由以大斑块为主体,散布型斑块镶嵌其中转变为以中等斑块为主体,散布型斑块镶嵌其中的构型;区域土地利用的斑块数由1014个增加到1889个,平均斑块面积由1.02km2/个减少到0.55km2/个;流域土地利用空间格局指数中多样性指数增长4.14%,均匀度指数增长4.14%,破碎度指数增长84.6%,优势度指数降低1.6%;未利用地、林地的分离度分别增加114.58%和69.64%,而耕地的分离度减少45.86%;流域耕地、建设用地重心向东北方向偏移,而未利用地、林地重心向南东、南西方向偏移。引入社会、经济数据分析,人口增长、经济发展是流域耕地增加进而导致系列土地利用变化的主要人文驱动力,而生态环境保护等宏观政策是流域林地变化的主要驱动力。

The land use change graph from 1982 to 2003 of Xiaojiang watershed in typical karst region was analyzed by GIS based on 2 times spatial data. The results showed: (1) the cultivated land increased was the most important changes, which was transformed from unused land. 610.12 km^2 land use had been changed, of which ~268.5 km^2 or 44.01% of the total was changed into cultivated land during the past 20 years in Xiaojiang watershed. (2) The annual change rate of regional land use was 2.95%, while the annual change rate of cultivated land, unused land and forestland were ~10.55%, 4.08% and 5.95%, respectively. (3) The spatial pattern of land use in Xiaojiang watershed changed from composed of large and scatter patches mosaic to compose of middling and scatter patches mosaic, and the types of dominating patch have also been changed, which changed from unused land and forestland patch to cultivated land and forest land patch. (4) When the spatial pattern of land use in Xiaojiang watershed was analyzed quantitatively by introducing the diversity index, dominance index, homogeneity index and broken index, a clear picture of the interference degree caused by human activities can be made. As the increasing of disturbances from human, the diversity index, the homogeneity index and the broken index all increase, especially the broken index increased by 84.6%. (5) By analyzing of the change of the land use gravity center, the change of land use spatial pattern was very obvious during the past 20 years in Xiaojiang watershed. The land use gravity center has changed in different speed. Finally, analyzed quantitatively by introducing society and economy data, it was clarified that the rapid growth of population and the economic development for survival were the main driving forces of land use change in Xiaojiang watershed during the past 20 years. Furthermore, macro-policies such as ecological protection were also important human driving forces of land use change.