Soil moisture is an important indicator for monitoring soil degradation.lt has devastating impacts on agriculture, water resources,economy and environment.lt plays an important role on the water and energy exchange at the land surface/atmosphere interface.The method of the traditional monitor soil moisture can get single data, and can hardly acquire the soil moisture of large area.Remote sensing can provide information on large area quickly and easily,so it is significant to do research on how to monitor soil moisture by remote sensing.TM data on April 17,1984(pl25r39) is chosen as study area, where overlay to the earth's surface changes to the dense plant from the bare soil,which complies with the requirements of TVDI.So TVDI is chosen to retrieve soil moisture.Brightness temperature equation of the TM6 wave band is used to calculate land surface temperature(Ts).With TM3,TM4 wave band Normalized Difference Vegetation Index(NDVI) is calculated; Ts and NDVI are used as basic parameters, the dry-wet edges are defined using the middle ranges of NDVI.and based on the features of Ts-NDVI space;the ranks of soil moisture are divided according to TVDI.%土壤水分是监测土地退化的一个重要指标,是气候、水文、生态、农业等领域的主要参数,在地表与大气界面的水分和能量交换中起重要作用.传统的监测土壤水分的方法只能得到单点的数据,很难获得大范围地区的土壤湿度.遥感能够快速方便地获取大区域的地表信息,因此使用遥感监测土壤水分意义重大.主要利用了温度指标干旱指数对三峡库区进行土壤水分反演及其验证.利用TM6波段的亮温方程,计算得出地表温度(Ts),以TM3、TM4波段计算得出归一化植被指数(NDVI);把Ts和NDVI作为基本参数,根据Ts-NDVI特征空间的形状,取中间范围的NDVI,拟合干湿边方程,确定干湿边参数;根据温度植被干旱指数( TVDI)进行土壤湿度等级划分.结果表明,利用TVDI可以很好地反演出地表的土壤湿度信息.
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