石羊河流域中下游绿洲地区耕地利用变化研究(英)

基于1995和2000年Landsat TM影像的土地利用空间数据(1:100000),运用GIS空间分析方法研究了1995～2000年甘肃省石羊河流域中下游地区武威绿洲和民勤绿洲耕地利用现状、耕地扩展与流失的空间分布特征、变化幅度.结果表明:1)耕地是武威绿洲和民勤绿洲最主要土地利用类型之一.耕地与其他土地利用类型之间的相互转化空间分布广泛;2)中下游耕地均处于快速增长状态.1995～2000年下游民勤绿洲耕地年变化率为0.3282,年平均增长率达到2.18%;3)中游武威绿洲耕地扩展来源于草地和未利用地,二者占耕地增长面积的90.83%;耕地流失主要为农村居民用地扩展和耕地退化;4)下游民勤绿洲耕地扩展突出为草地转耕地,占耕地扩展总面积的54.58%.耕地流失最主要是耕地退化为未利用地和荒草地;5)缓冲空间分析表明,石羊河流域中游耕地扩展面积与下游耕地流失面积呈现显著正相关,相关系数为0.8856.中游武威绿洲耕地每增加1 hm2,将导致下游民勤绿洲3 hm2左右耕地减少.

Farmland use changes at oasis areas in the middle and lower reaches of Shiyang River Basin, Gansu Province of China

Based on land use spatial data (1100000) of Landsat TM image in 1995 and 2000, by using GIS technology, the spatial distribution characteristics and change range of farmland use status qun, farmland expansion and losses of Wuwei oasis and Minqin oasis of Gangsu Province, China in the middle and lower reaches of Shiyang River Basin (short for SYR basin) from 1995 to 2000 were investigated. The results show 1) farmland is the main type of land use in Wuwei oasis and Minqin oasis, the spatial distribution of possible transformation between farmland and other types of land use is broad; 2) farmland in middle and lower reaches of the SYR basin increased rapidly, the annual change ratio of farmland of Minqin oasis in the lower reaches of the SYR basin from 1995 to 2000 was 0.3282, the annual mean rate of increment reached 2.18%; 3) farmland expansion of Wuwei oasis in the middle reaches of the SYR basin originated from grassland and unused land, which accounted for 90.83% of the increased farmland areas, and farmland losses were caused by rural residential land expansion and farmland degradation; 4) farmland expansion of Minqin oasis in the lower reaches of the SYR basin typically resulted from grassland, which accounted for 54.58% of the total expanded areas, and farmland losses were mainly caused by degrading farmland to unused land and barren; 5) buffer analysis shows that there is a significant positive correlation between farmland expansion area in middle reaches of the SYR basin and farmland loss area in the lower reaches of the SYR basin, and the correlation coefficient is 0.8856. Increasing each 1 hrn2 farmland of Wuwei oasis in the middle reaches of the SYR basin causes about 3 hm2 farmland loss of Minqin oasis in the lower reaches of the SYR basin.