利用TM系列影像监测盐碱化土地变化——以民勤绿洲为例

选择盐碱化灾害严重的民勤绿洲地区,结合植被指数和地面温度以及目视解译的土地利用图,对4个不同年份的TM遥感影像进行信息压缩与提取,完成土地利用与覆盖的自动分类,获得不同时期、不同程度的盐碱化土地面积,进行对比分析.选择两个典型地区,结合气象、经济、地下水等观测和统计资料,研究盐碱化土地面积变化的成因.结果发现民勤绿洲地区的盐碱化土地面积一直处于下降趋势,地下水是影响土地盐碱化变化最主要的因素.

Study on the saline soil changes using TM in Minqin Oasis,Northerwest China

Salinization is one of the serious disasters in Minqin Oasis Region, Northwestern China and it has a close relationship with not only natural change but also human activity. In order to understand the changes of saline soil in this region we use four different years, TM images to get the land use maps. Temperature and NDVI are evaluated for the four years, which can highlight the saline land in the two dimensions. From the reflective images we get principal components and select the first three principal components, NDVI and temperature for classification. Referring to the land use maps derived from visual-interpretation, we use supervised classification to set up rules and classifiers and finally get the distributions of saline land of Minqin Oasis in the four different years. The changes in saline land are diagramed, which tells us that the trend of saline land in Minqin Oasis Region is reduced from 1987 to 2000. Two typical regions, namely Baqu and Huqu, are discussed, showing the different changes in saline land in the south and north of Minqin Oasis. Compared with the changes of groundwater level, saline lands have been reduced with the reduction of groundwater, which indicates that both places have a similar trend and groundwater is the main factor that influences saline lands in the study area. Besides, natural and manmade influences are discussed.