Groundwater storage is defined as the volume of water held in an aquifer that can be released or stored, determined by the saturated thickness, drainage base, and storage characteristics of the aquifer. Changes in groundwater storage result from the balance between recharge and discharge over time. How useful is this definition?

To ensure sustainable groundwater use, it is important to conserve groundwater by regulating its extraction and securing alternative water sources. Continuous and excessive extraction of groundwater induces land subsidence, resulting in lower groundwater levels and salinization (Figure 1.1).

Groundwater storage is the volume of water stored in the aquifer that potentially can be released or stored. It is determined by the saturated thickness, the drainage base of the aquifer and storage characteristics (Section 3.4.1). Groundwater storage change is the difference between groundwater recharge and discharge over a timeframe of interest.

Water that infiltrates past the root zones of crops may percolate into aquifers and be stored as groundwater. Some WH techniques collect runoff to encourage infiltration to increase groundwater storage, and others store water at the surface in natural or man-made ponds or tanks. Water is later withdrawn for irrigation or other productive uses.