It is widely recognized that natural heterogeneity and the large spatial variability of hydraulic parameters control the spread of contaminants and water in the subsurface. Similarly, hydrological and biogeochemical processes are variable over a wide range of spatial scales. The inadequacy of conventional (wellbore) approaches for characterizing or monitoring the parameters and processes at over large enough areas yet with high enough resolution hinders our ability to optimally manage our natural water resources. GPR methods hold promise for improved and minimally invasive characterization and monitoring of the subsurface. This paper will review several case studies where we have successfully used GPR for a variety of environmental and precision agricultural investigations.