近50a阿克苏河流域土地利用/覆被变化过程

Land Use/Cover Change of the Aksu River Watershed in the Period of 1960-2008

针对干旱区跨境河流域土地利用/覆被变化(LUCC)研究薄弱、无法满足环境变化评价的问题,选择西天山跨越吉尔吉斯斯坦国和中国的阿克苏河流域为研究区,在遥感和GIS的支持下,获取了近50a阿克苏河流域土地利用/覆被数据,并利用数理统计模型,对该流域LUCC的过程、趋势及土地利用程度变化进行系统分析.结果表明:阿克苏河流域土地变化从前期(1960-1990年)的准平衡状态转变为后期(1990-2008年)的不平衡状态,土地类型也呈现出从双向转换向单向转换过渡,且不同类型差异较大;流域后期LUCC的速度是前期的2.1倍,其中耕地和建设用地增加最快而沼泽地和盐碱地减少最快,草地变化速度最小.流域土地利用处于发展时期,且流域下游绿洲区域土地利用程度综合指数及其变化较大.政策调整、人类活动增强、气候变化以及径流变化是LUCC的主要驱动因子.

The information of the land use/cover （LUC） change in the tans-boundary river watersheds is not enough to meet the requirements of evaluating environmental change. The Aksu River is the largest trans-boundary river crossing Kyrgyzstan and China,the LUC of which is studied in this paper. In present study,data of LUC change during the period 1960-2008 over the Aksu River watershed are derived with the supports of Geographical Information System and Remote Sensing techniques,based on which the processes,trends of the LUC change,as well as the dynamics in land use degree,are analyzed by a set of mathematical statistical models. It is found that the studied area changed from the quasi-balanced status in the first stage （1960-1990） to the unbalanced status in the second stage （1990-2008）. The land type transition shifted from the two-way transition to one-way transition,and the overall net change rate of the LUC in the second stage was 2.1 times of that in the first stage. The cropland and construction land increased largely,while the wetland and saline land decreased largely. The land use is in a developing period,and the oasis in the lower reaches has the highest land use degree and changes greatly. These changes are tightly related to the policy shifts,human-activity enhancements,climate and runoff variations.