黑河分水后额济纳绿洲生态恢复的遥感定量测算

以2000,2003年陆地卫星遥感影像为信息源,通过遥感和GIS技术,据土壤调节植被指数和植被覆盖度结合土地覆盖/利用转移矩阵,剖析了黑河分水3年来额济纳地区土地覆盖类型的面积变化、空间变化、质量变化等特征,对分水前后额济纳绿洲生态环境状况进行了定量测算和对比.结果表明:水资源驱动下额济纳绿洲及其周边地区生态环境确有好转,各植被覆盖类型面积均有扩展,总计增长11.9%;植被覆盖度提高,盖度集中区间迁移趋向主要由0.0,0.05]转换至0.05,0.30],比例为13%;空间演变为绿洲外围的低覆盖度植被大量生长,绿洲三角洲枯败的荒漠河岸林植被恢复生机,大面积水域重现;河流廊道区恢复效果好于外围区域.

Remote sensing based quantitative estimation of ecosystem restoration of Ejina Oasis after the Heihe River water was transferred

The evolvement of Ejina Oasis is a most representative case in sharp environmental degeneration which urged the implementation of the water transferring project of the Heihe River. The data in this paper are derived from Landsat TM/ETM+ images in 2000 and 2003; then two parameters-soil adjusted vegetation index (SAVI) and vegetation fraction are inverted. Based on Remote Sensing and GIS, we make use of SAVI and vegetation fraction as well as LUCC transfer matrix to analyze the characteristics of spatial and qualitative changes in Ejina Oasis, thus achieving the quantitative estimation of ecosystem restoration after three years' water transferrence. The results show that the environment of Ejina Oasis is really restoring which is mainly driven by water resource transferred from upper and middle reaches of the Heihe River: areas of land covered by vegetation expanded, with a total increase of 11.9%; vegetation fraction increased too and the leading trend is that vegetation fraction concentrated in worse grade 0.0, 0.05] has been transferred to generic grade 0.05, 0.30], taking up 13% proportion; the spatial pattern change is that lower covered vegetation has grown a lot in the periphery of oasis, arboreal forest distribution along the river came back to vital force and great water areas reappeared in this region; the ecological restoration of river corridors is better than their contiguous areas.