科尔沁沙地近水区域沙漠化空间分布规律初步研究——以奈曼旗为例

Distribution of Sandy Desertification around Surface Waters in Horqin Sandy Land: Case Study in Naiman Banner

以奈曼旗作为案例研究地,以1987年和2002年的Landsat/TM影像为基本数据源,按与水体的空间距离,对水体周边区域的裸沙地面积百分比进行分地带统计。该过程通过ArcGIS平台下的缓冲区分析完成。结果发现,奈曼旗的沙漠化程度的空间差异与地表水的空间分布关系密切。总体来讲,奈曼旗境内主要水体周边的沙漠化程度随空间距离变化有明显的差异,从水体边界开始,随着与水体空间距离的增加,裸沙地面积百分比值不断升高,并在距离湖泊水库1 km处、距离教来河北段2 km处、教来河南段6 km处和老哈河7 km处,裸沙地面积百分比值达到极大。在更远距离,老哈河、舍力虎水库、西湖水库周边的裸沙地面积百分比值随距离增加而迅速下降,教来河北段和教来河南段周边的裸沙地面积百分比值随距离增加呈缓慢下降趋势,孟家段水库周边的裸沙地面积百分比则略有波动,从5 km距离后呈迅速下降趋势。按水体的空间格局划分,奈曼旗的沙漠化程度被划分为4个不同程度的区域。以上现象说明,地表水及其利用在奈曼旗的沙漠化发展过程中起到了非常重要的作用。

The vectors of surface water boundaries in Naiman Banner of Inner Mongolia were extracted with Landsat/TM images in 1987 and 2002. Buffers of the boundary vectors were built up and the indicator of area percentage of sandy land in each buffer was computed with the ArcGIS tools. Results showed that the extent of sandy desertification and the location of the surface waters were closely related. There was usually an extremum of the area percentage of sandy land at the spot that is about 1 to 7 km away from the boundary of the surface water. The area percentage of sandy land increased from the surface water boundary to the extremum spot, and it decreased from the extremum spot to the distance farther away. Land use, supplementing to climate change, was the major impact factor to the distribution of the sandy desertification and its changes. During the period from 1987 to 2002, plantation were concentrated to the places very closed to surface waters in the study area. It helped to decrease the pressure of land use in places that are far from surface waters, and then helped to decrease the extent of sandy desertification.