ABSTRACT
By definition, an unconfined aquifer has a water table. The water table is not an interface separating saturated from unsaturated zones. It is the surface where the pressure is atmospheric (i.e., gauge pressure is zero). Depending on the height of capillary fringe, the saturated-unsaturated interface can be a few centimeters to a couple of meters above the water table. The water in the capillary-saturated pores is not directly extractable by pumping; however, the capillary-saturated zone can fall with the lowering of the water table. Generally, water in an unconfined aquifer is extracted through gravity drainage of pores while water in a confined aquifer is extracted through aquifer compression and pore water expansion such that the confined pores remain saturated during pumping. Extensive pumping can lead to a locally unconfined condition around the pumped well in a confined aquifer.
