1986-2009年高台县绿洲化荒漠化时空过程

以1986-2009年的8期Landsat TM/ETM+影像作为数据源,提取了高台县的绿洲和荒漠分布范围,并使用动态度模型、变化检测和重心模型分析了绿洲在时间序列上的数量和空间格局变化.结果表明:这24年高台县绿洲面积不断增加,荒漠面积不断减少,其中1999-2002年绿洲的扩张速度达到最大;绿洲的扩展区和退缩区虽然分布比较零碎,但主要集中在南部的红崖子乡、西北部的盐池乡以及中部的宣化镇和东部的合黎乡和南华镇一带;绿洲重心向北迂回迁移了0.615 km,荒漠重心大致由南向北迁移了1.131km,绿洲重心的迁移范围主要在骆驼城和宣化乡林场之间,荒漠重心的迁移范围主要在黑泉乡一带.

Spatio-temporal changes of oasis and desertification in Gaotai county from 1986 to 2009,Gansu province

The oasis and desert in Gaotai county were extracted and separated by Landsat TM and ETM images acquired between 1986 and 2009.Then the changes in qualities and spatial distributions of oasis and desert were analyzed with a dynamic model and a change detection and barycenter transfer model during 1986-2009.The result shows that from 1986 to 2009 the area of oasis increased continuously and desert decreased correspondingly; the expanding speed of oasis reached a peak during 1999-2002.While the expansion and shrinkage were irregular and scattered,they were located in the typical areas including Hongyazi in the southern part of Gaotai county, Yanchi in the northwest,Xuanhua in the middle part and Heli and Nanhua in the east.The study with the barycenter transfer model indicates that,from 1986 to 2009,the oasis’s center of gravity shifted northward with a distance of 0.165 km.On the contrary,the barycenter of desert headed from south to north on the whole and the transfer distance was 1.131 km,the barycenter direction of oasis was located between Luotuo township and Xuanhua forest farm,and the barycenter direction of desert was located in Heiquan.