An automated multi-satellite approach for soil moisture mapping using visible/infrared, passive microwave data and topographic attributes

This work presents a methodology for soil wetness mapping over a northern watershed. The approach is based on the use of a combination of passive microwave data from AMSR-E images, visible data provided by MODIS sensor and topographic attributes from a Digital Elevation Model. Classic topographical wetness indices, which are defined exclusively using topographic attributes, are static and unable to catch the temporal variability of soil moisture. In this work, we propose to overcome the static behavior of classic topographical wetness indices by assessing the temporal variability of the soil water content using passive microwave data and by introducing the vegetation effect into a wetness index. AMSR-E 37 GHz will be used to assess the wetness of the area. The proposed approach is an improvement in a dynamic sense over the classic topographic indices. The new topographic wetness index will downscale the global information about soil moisture provided by passive microwave data and take into account the variability of the surface conditions in the basin. The results obtained were compared to those derived from the classic index to assess the reliability of the dynamic index. The proposed index has provided a better estimation of the wetness over the basin. This implies that a combination of passive microwave data and topographic attributes has an interesting potential to improve the water balance closure over northern basins.