多源NDVI在玛纳斯河流域荒漠化监测中的应用

为了对玛纳斯河流域荒漠化进行长期准确地监测,在分析MOD13A1-NDVI(归一化植被指数)与同期8 km×8 km AVHRR-NDVI数据的基础上,建立了基于两种不同NDVI数据的荒漠化分级指标体系。利用相应的分类体系进行了流域荒漠绿洲带1982~2008年荒漠化的遥感监测,并结合19892、000和2008年8月Landsat-5/TM数据,分析了3种不同NDVI数据在空间上的差异性,并进一步分析了荒漠化演变的原因。结果表明:(1)同期AVHRR、MOD13A1和Landsat-5/TM监测结果显示出相似的空间差异性,绿洲带北部紧连古尔班通古特沙漠地区植被覆盖稀疏,NDVI较小;南部绿洲灌溉区植被覆盖较好,NDVI整体上较大。植被覆盖具有显著的空间差异性,这与地形因素、水分、热量条件、地貌形态和土壤理化性质等气候环境因子存在联系。(2)近20 a来,绿洲带外围不断向南迅速扩展,由20世纪80年代初的11 200 km2增加到90年代末的12 672 km2,增加了1 472 km2;绿洲带内部以石河子垦区为中心,NDVI呈辐射状逐年线性增加。(3)近8 a来,绿洲内部变化不大,荒漠带中盐渍化土地增加显著,2008年面积为1 906 km2,较2000年增加了1 712 km2,东部丘间盆地被开垦耕地面积196 km2。

Application of multi-source NDVI data to desertification monitoring in the basin of the Manasi River

We built two NDVI data classification index systems based on analysis of every ten-day 500 m×500 m MOD13A1- NDVI data and the same period''s 8x8km AVHRR-NDVI data, for long term precise desertification moni-toring in the basin of the Manasi River. Then we analyzed spatial-temporal pattem differences of three kinds of NDVI data and further give the reason of deserification, in a combination with Landsat-5/TM data of eight months in the years of 1989, 2000 and 2008. The results show: (1) In the same period, the monitoring results reveal similar spatial-temporalpattem change trends interchangeably using AVHRR, MOD13A1 and Landsat -5/TM data. The north of oasis band adja-cent to Gurbantonggut Desert is covered by sparse vegetation and the corresponding NDVI is small. The south asis is covered by well-growing vegetation and the NDVI there is larger on the whole. Vegetation covering has striking spatial-temporal pattem differences associated with environmental factors, such as terrain factors, water, heat conditions, geo-morphological pattems, and soil physical and chemical properties. (2) In the last twenty years, the periphery of oasis band extended rapidly to the south, from 11 200 km² in the mid 1980s to 12 672 km² in the late 1990s, with an increase of 1472 km²; in the interior of oasis NDVI is increasing annually in a linear trend at the reclamation area with Shihezi as the center. (3) In the last eight years, the interior of oasis had lttle changes , and the salinization of soil in the desertifi-cation zone has increased significantly, the area enlarged from 1712 km² to 1 906 km2 during 2000 to 2008, and the east mountain basins have been reclaimed with an area of 196 km².