Microwave Remote Sensing of Soil Moisture in Semi-arid Environment

Abstract

Soil moisture, defined as the water content in the upper layer of soil, is the hydrologic variable that controls the interactions (and feedbacks) between land surface and atmospheric processes (Hossain and Anagnostou, 2005). Soil moisture is important in the distribution of precipitation between runoff and infiltration (Baghdadi et al., 2006). Soil moisture monitoring and characterization of the spatial and temporal variability of soil moisture at scales from small catchments to large river basins is important in the understanding of subsurface – land surface – atmospheric interactions as well as, drought analysis, crop yield forecasting, irrigation planning, flood protection, and forest fire prevention (Georgakakos and Baumer, 1996, Robock et al., 2003). Surface soil moisture distribution information is a critical forcing variable in many Soil Vegetation Atmosphere Transfer (SVAT) models to estimate profile soil moisture at daily time steps. Soil moisture distribution also plays a key role in the prediction of erosion and sediment loads in watershed streams and ponds. In arid and semi-arid watersheds soil moisture content has been used as a surrogate indicator of general plant health (Moran et al., 2004).