Unconfined Groundwater

Abstract An unconfined aquifer is a geologic formation with subterranean water that is not confined by relatively impermeable layers. Part of the precipitation and irrigation water as well as water from recharge basins, reservoirs, and ponds moving downward from the soil layer will reach the saturated groundwater zone. The top of this zone is the water table, which separates the fully saturated zone from a partially saturated zone. The latter zone is simply referred to as the unsaturated zone, but it is also known as the zone of aeration or vadose zone. Generally, the water in the unsaturated zone is under less than atmospheric pressure. The unsaturated zone includes the capillary fringe, directly above the water table, which is near saturation but still under negative pressure relative to the atmospheric pressure.