塔里木河下游沙漠化土地时空变化遥感分析

为对应急输水工程实施前后塔里木河下游地区沙漠化土地的变化状况进行监测，选择研究区1999年TM、2002年ETM+和2004年ASTER遥感影像及基础地理数据，通过沙漠化土地分类体系划分、信息提取模型构建及动态变化类型建立等方法，对研究区沙漠化土地的时空变化趋势进行了定性定量分析。结果表明：应急输水工程实施后，研究区内非、轻沙漠化面积逐年增加，分别由1999年的14 768.33、153 261.03 hm2增加至2004年的19 994.23、159 953.76 hm2；中度沙漠化面积年均减少2 981.58 hm2；强度沙漠化面积仅增加1.07 hm2。研究期间，部分沙漠化土地发生了较为明显的逆转，土地持续退化局面有所遏制和缓解，但由于来水量有限及采用线性输水等原因，远离河道区域的生态环境依然恶劣，流域整体生态环境仍不容乐观。

Remote sensing analysis of spatial-temporal changes of desertification land in Lower Reaches of Tarim River

The respective data of TM, ETM+ and ASTER in1999, 2002 and 2004 and together with the basic geographic data in the Lower Reaches of Tarim River were monitored, collected and analyzed in qualitative and quantitative way before and after the emergent water project in the Lower Reaches of Tarim River. Classifying the desertification land, modeling the target information extraction and establishing the dynamic change patterns, the spatial-temporal changing trend of desertification land in the study area showed that the none and weak desertification area increased from 14 768.33, 153 261.03 hm2 in 1999 to 19 994.23, 159 953.76 hm2 in 2004, respectively. The moderate desertification area decreased by 2 981.58 hm2 on average annual, and the severe desertification area went up only by 1.07 hm2. During the period of research, some desertification lands were evidently reversed and in turn the continuing trend of land degeneration was partly stopped and alleviated. The ecological environment far away from the river bed, however, was still bad and severe, and the entire ecological environment of the river basin was less optimistic because of the limited water inflow coming from the emergency water project as well as the linear water delivery.