基于GIS和分形理论的沱江流域土地利用结构动态分析

以沱江流域2000年、2020年土地利用空间数据库为基础，应用GIS技术及分形理论，定量分析研究区土地利用空间结构复杂性、稳定性以及空间分布规律。结果表明：(1)各种土地利用类型都具有分形特征，分形维数可以表征土地利用空间格局的变化。(2)20年间，沱江流域的土地利用类型以耕地和林地为主，占研究区总面积的90%以上，受人为活动影响，流域内不同土地利用类型之间存在相互转化的过程，主要的转化特点是耕地和林地大面积减少，而城乡建设用地迅速扩张。(3)流域2期土地利用的总分形维数分别为1.351、1.503，上升趋近于临界值1.5；土地利用整体空间结构稳定性指数从0.149下降到0.003，说明总体上流域土地空间镶嵌结构趋于复杂化，稳定性变差。(4)流域各地类的分形维数和稳定性指数变化存在一定差异，除未利用地外，其他土地利用类型的分形维数均呈变大趋势，空间镶嵌结构趋于复杂化；耕地、林地、草地、城乡建设用地稳定性指数均减小，减小的幅度分别达80.137%、52.439%、55.556%、26.957%，空间结构变得不稳定；水域稳定性指数变大，空间结构变得稳定。

Dynamic Analysis of Land Use Structure in Tuojiang River Basin Based on GIS and Fractal Theory

Based on the spatial land use database of Tuojiang River Basin in 2000 and 2020 year, the complexity, stability and dynamic change of the spatial structure of land use were quantitatively analyzed by using GIS technology and fractal theory. The results showed that, (1) All land use types had fractal characteristics. Fractal dimension could represent the change of land use spatial pattern. (2) In the past 20 years, the land use types in Tuojiang River Basin were mainly cultivated land and forest land, accounting for more than 90% of the total area of the study area. Affected by human activities, there was a process of mutual transformation between different land use types in the basin. The main characteristics of land transformation were that cultivated land and forest land decreased in a large area, while urban and rural construction land expanded rapidly.(3) The total fractal dimensions of land use in the two stage of Tuojiang River Basin were 1respectively.351 and 1.503, rising to 1.5, the stability index of the overall spatial structure of land use decreased from 0.149 to 0.003, which indicated that the spatial mosaic structure of land in the basin tended to be more complex and the stability became worse.(4) There were some differences in fractal dimension and stability index of different land use types in Tuojiang River Basin. Except for unused land, the fractal dimension of other land use types tended to increase, and the spatial mosaic structure tended to be complex. The stability index of cultivated land, forest land, grassland and urban and rural construction land decreased by 80.137%, 52.439%, 55.556% and 26.957% respectively, and the spatial structure tended to be unstable. The stability index of water area became larger, and the spatial structure of land use type tended to be stable.