塔里木河干流人工与天然绿洲转化及适宜比例研究

利用1990,2000,2010年3期Landsat TM/ETM遥感影像,基于RS/GIS技术,分别提取土地利用/覆被类型信息,分析1990~2010年塔里木河流域人工绿洲和天然绿洲的变化规律及其比例,探讨该区人工绿洲和天然绿洲的适宜配比。研究结果表明:(1)1990~2010年,研究区域人工绿洲呈不断扩张,天然绿洲面积不断缩小,人工绿洲替代天然绿洲的趋势。(2)1990~2010年,人工与天然绿洲总面积几乎无差异,面积变化主要是人工绿洲与天然绿洲之间的相互转换。具体表现为:天然草地、林地等向人工绿洲中的耕地、建筑用地转化;同时植被长势衰退:高覆盖草地向中、低覆盖草地转化,中覆盖草地向低覆盖草地转化,灌木林地逐渐退化为草地,低覆盖草地向沙漠转化。(3)人工与天然绿洲面积比例在近20 a呈增加的趋势,在1990,2000,2010年,人工与天然绿洲面积比值分别是1∶9,2∶8,3∶7。

Study on artificial and natural oasis mutual conversion process and their proper ratio in main stream of Tarim River

According to the Landsat TM/ETM images of 1990, 2000 and 2010 in Tarim River basin, we extract the land use and land cover type based on RS/GIS. Based on the results we research the conversion process of artificial and natural oases in 1990~2010, and discuss the rational area ratio between artificial oasis and natural oasis. The results showed that: the artificial oasis was in a continuous expansion, and natural oasis area was in shrinkage in the basin from 1990 to 2010; the total oasis area in the period was in stable, so just a conversion between the artificial and natural oasis happened, namely the natural oasis of grassland and forest land, etc. gradually changed into artificial oasis of cultivated land, construction land, etc., at the same time, vegetation grow showed a declined trend that high-cover meadow changed into middle and low-cover meadow, mid-cover meadow changed into low-cover meadow, shrub land gradually degraded to meadow, and low-cover meadow degraded into desert; in 1990, 2000 and 2010, the ratio of artificial oasis to natural oasis were 1:9, 2:8, 3:7 respectively, showing a upward trend.