基于归一化植被指数和地表反照率的土地沙漠化遥感监测研究

Remote Sensing Monitoring of Land Desertification Based on Vegetation Index and Surface Albedo

目的对土地沙漠化状况进行监测和评价,研究土地沙漠化变化及趋势预测,为恢复植被覆盖和改善生态环境提供依据.方法以新疆昌吉为研究区域,采用Landsat遥感影像,经过预处理后通过提取归一化植被指数和地表反照率的空间特征,获取沙漠化差值指数,分析与评价新疆昌吉地区的沙漠化程度.结果新疆昌吉地区2011年沙漠面积为62.29%,裸地面积为26.97%;2013年沙漠面积为59.92%,裸地面积为28.59%;2015年的沙漠面积为77.73%,裸地面积为18.14%.2011—2013年,沙漠化差值指数增大,沙漠面积减少;2013—2015年,沙漠化差值指数显著减小,土地沙漠化面积大幅度增加;沙漠化等级由中度沙漠化演变为轻度沙漠化,又由轻度沙漠化变为重度沙漠化.结论沙漠化差值指数与沙漠化等级呈负相关性,DDI可正确地反映土地沙漠化的变化情况.

To provide the basis for restoring vegetation cover and improving the ecological environment,the desertification status of land was monitored and evaluated to study the desertification change and predict the trend.From the Landsat remote sensing image in Changji and surrounding areas of Xinjiang,the spatial characteristics of normalized vegetation index(NDVI)and surface albedo(Albedo)were extracted to obtain the desertification difference index(DDI)which is used to analysis and evaluate its desertification.As a result,in 2011 the desert area was 62.29%and the bare land area is 26.97%;in 2013 the desert area is 59.92%and the bare land area is 28.59%;in 2015 the desert area is 77.73%,and the bare land area is 18.14%.From 2011 to 2013,the desertification difference index increased and the desert area is reduced;from 2013 to 2015,the desertification difference index has decreased significantly and the desertification area of?land has increased significantly.The desertification grade changed from moderate desertification to mild desertification,and from mild desertification to severe desertification.The desertification difference index(DDI)is negatively correlated with desertification grade,and DDI can correctly reflect the change of land desertification.