ABSTRACT
Groundwater recharge from the vadose zone occurs when soil water crosses the water table of a perched aquifer or the phreatic zone. Recharge is important where hydrologists may be required to quantify the perennial yield of a groundwater basin in order to assess, for example, the potential viability of an irrigation project, the adequacy of a municipal water supply, or the feasibility of dewatering a mine pit. This chapter highlights some of the numerous studies that report the widespread occurrence of recharge, in even the most arid deserts. Diffuse recharge is natural recharge derived from precipitation that falls on large portions of the landscape and percolates through the vadose zone to the aquifer. Diffuse and, to a lesser extent, local recharge are relatively large-scale processes within a groundwater basin. In humid climates, most groundwater recharge probably occurs by diffuse percolation of precipitation.
