unsaturated zone  search
UFnon-saturated zone
 vadose zone
 zone of aeration
RTsoils
 ground water
 hydrogeology
 SUTRA
 preferential flow
 capillary water
 saturated zone
 water table
 underground streams
 water regimes
 Green-Ampt model
 DRAINMOD
 infiltration
 Richards equation
SNSubsurface zone with pressure less than atmospheric. In GeoRef, it is not considered ground water. Added to Thesaurus in 1981.