Radar Measurement of Surface Water Content Dynamics Under Wheat Canopy

Ground penetrating radar (GPR) with a suspended 1 GHz horn antenna was deployed for measurement of soil water contents and dwarf wheat canopy reflections over bare and electrically terminating surfaces. Surface reflection (SR) magnitudes and propagation times (PI) were used to independently calculate bulk soil dielectric constant and soil water contents. Measurements over wheat canopy shows that while SR and reflection coefficient values were strongly altered by canopy biomass, PT measurements remain unaffected. Wheat canopy influence on SR gradually intensified during the growth season until the canopy was removed and SR-based measurements rejoined with PT data. Horn-antenna radar measurements over natural surfaces offer a promise for remote truthing of radar data collected from air- and spaceborne platforms, and they may be used in the field for water content and vegetation biomass measurements