Remote Sensing of Soil Moisture: An Overview in Relation to Coastal Soils

Soil moisture plays an important role in the exchange of water and heat energy between the land and atmosphere and is used in studies of global climate change. Soil moisture data are also required for reservoir management, early warning of droughts, irrigation scheduling, and crop yield forecasting. Coastal soils in general span the gamut of soil properties necessary for agriculture and maintaining natural environments, including transitional wetlands. Beach characteristics, such as soil moisture, grain size and type, are needed for determining substrate-bearing strength, modeling beach erosion, and planning beach nourishment. Because microwave radiation from soil is strongly dependent on moisture content, soil moisture has traditionally been mapped with airborne microwave radiometers. Innovative antenna technology has enabled microwave radiometers on satellites, such as Soil Moisture and Ocean Salinity and Aqua, to measure soil moisture on a global scale. Better corrections for surface roughness, vegetation cover, soil temperature, and topography must still be devised, and techniques for sensing soil moisture beyond the top few centimeters developed.