利用 2 0世纪 70年代航测资料和 80年代中后期及 90年代中期LandsatTM 3个不同时期的遥感影像 ,在GPS的辅助下 ,对遥感图像进行精确的几何纠正 ,并投影到统一的坐标系统 ;在建立统一的解译标志基础上进行人工判读 ,并利用GIS对荒漠化土地信息进行管理和分析 ,调查了中国典型的荒漠化地区———甘肃省民勤县的荒漠化土地变化状况。结果表明 :近 30年来民勤县的荒漠化土地面积呈现增加的趋势 ,但是1 985年以来荒漠化土地的扩展速度有所变缓 ;流动和半流动沙丘的面积持续增大而固定和半固定沙丘得到有效的控制。同时 ,利用野外调查和各种数据分析 ,从自然环境和人文因素两个方面分析探讨了研究区近 30年荒漠化变化的原因

Aided by GPS, geometric correction of aero photos of 70s, TM images of 80s and 90s were accurately done for desertification analysis. And they were also consolidated to the same projection. Based on setting up of accordant interpretation keys and managing and analyzing of desertification land information by GIS, dynamic change of desertification land was investigated in Minqin County of Gansu Province, a typical desertification region. The results show: the area of desertification land in Minqin County tends to enlarging in recent 30a. However, the spreading rate was slow down since 1985. The areas of active dune and semi active dune are increasing continually while the areas of fixed dune and semi fixed dune were controlled effectively. Finally, the reasons of desertification changing of this region were discussed in two aspects including both natural environment and social factors by fieldwork and data analyzing.