Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic formations.

Groundwater can be found at nearly every point in the Earth's shallow subsurface, to some degree; although aquifers do not necessarily contain fresh water. The Earth's crust can be divided into two regions: the saturated zone where all available spaces are filled with water, and The unsaturated zone, where there are still pockets of air with some water that can be replaced by water.

An uncontrolled use of the borewell technology has led to the extraction of groundwater at such a high rate that often recharge is not sufficient.

The causes of low water availability in many regions are also directly linked to the reducing forest cover and soil degradation.

The solid, liquid, and the gaseous waste that is generated, if not treated properly, results in pollution of the environment; this affects groundwater too due to the hydraulic connectivity in the hydrological cycle

Example, when the air is polluted, rainfall will settle many pollutants on the ground, which can then seep into and contaminate the groundwater resources.

Water extraction without proper recharge and leaching of pollutants from pesticides and fertilizers into the aquifers has polluted groundwater supplies.

Aquifers are typically saturated regions of the subsurface which produce an economically feasible quantity of water to a well or spring

Most land areas on Earth have some form of aquifer underlying them, sometimes at significant depths.

An aquitard is a zone within the earth that restricts the flow of groundwater from one aquifer to another

There are two end members in the spectrum of types of aquifers; confined and unconfined Unconfined aquifers are sometimes also called water table aquifers, because their upper boundary is the water table. Typically (but not always) the shallowest aquifer at a given location is unconfined, meaning it does not have a confining layer (an aquitard or aquiclude) between it and the surface

Confined aquifers have very low storativity values (much less than 0.01, and as little as ), which means that the aquifer is storing water using the mechanisms of aquifer matrix expansion and the compressibility of water, which typically are both quite small quantities.

The Ogallala Aquifer, also known as the High Plains Aquifer, is a vast yet shallow underground water table aquifer located beneath the Great Plains in the United States.

Global Warming Effects?

Groundwater recharge will rise dramatically in some areas and decrease in others — a direct result of soil-water-plant systems, which control it, amplifying the effects of rainfall variations. Because many countries have groundwater reservoirs that constitute a significant portion of their total water supply.

It is vital that policymakers and scientists gain a better understanding of the complex interactions between the climate, soil and groundwater. Doing so will allow us to predict future changes in the soil-water-plant systems more accurately and will also enable us to institute better water management practices when the time comes.