Soil Moisture Mapping in Typical Semi-Arid Regions of China by Using Envisat ASAR Data

Both passive and active microwave sensors have long been used in retrieving the soil moisture, however, only the SAR can provide the high spatial resolution data (10 m~1 km) suitable for watershed scale hydrological studies. In this paper, we took a preliminary study on deriving the catchment scale soil moisture content and their spatial variations in a typical semi-arid rangeland located at the Loess Plateau of China with active microwave remotely sensed data. The Advanced Integral Equation Model (AIEM) was coupled with the Envisat ASAR images by using the simulated surface roughness information retrieved from the multi-angle (15deg a 31deg) ASAR data as constraining condition to estimate the surface soil moisture content within the studied watershed, the Jinhe River Basin. In general, the soil moisture map derived from this study shows high wetness in most part of the basin, which is in agreement with the actual rainy condition in the study region.