Aquifer what is it used for

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Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. An aquifer is an underground layer of rock that holds groundwater.

Groundwater is water that has infiltrated the ground to fill the spaces between sediments and cracks in rock. Groundwater is fed by precipitation and can resurface to replenish streams, rivers, and lakes. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Image Aquifer House A water well system next to a house, showing how aquifers are an important source of water.

Graphic by NosorogUA. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. Part of this water is used by vegetation; some evaporates and returns to the atmosphere. Part of the water also seeps into the ground, flows through the unsaturated zone and reaches the water table, which is an imaginary surface from where the ground beneath is saturated see illustration below.

Image Water table, the saturated and unsaturated zones The Importance of Groundwater. Aquifers can consist of different materials: unconsolidated sands and gravels, permeable sedimentary rocks such as sandstones or limestones, fractured volcanic and crystalline rocks, etc. Groundwater is naturally recharged by rain water and snowmelt or from water that leaks through the bottom of some lakes and rivers. Groundwater also can be recharged when water supply systems leak and when crops are irrigated with more water than required.

There are also techniques to manage aquifer recharge and increase the amount of water infiltrating into the ground. Groundwater can be found almost everywhere. The water table may lie deep or shallow depending on several factors such as the physical characteristics of the region, the meteorological conditions and the recharge and exploitation rates. Heavy rains may increase recharge and cause the water table to rise. Larger pore spaces usually have higher permeability, produce less energy loss, and therefore allow water to move more rapidly.

For this reason, ground water can move rapidly over large distances in aquifers whose pore spaces are large like the lower Portneuf River aquifer or where porosity arises from interconnected fractures.

Ground water moves very rapidly in fractured rock aquifers like the basalts of the eastern Snake River Plain. In such cases, the spread of contaminants can be difficult or impossible to prevent. What does an aquifer look like? Every aquifer is unique, although some are more generic than others.

The boundaries of an aquifer are usually gradational into other aquifers, so that an aquifer can be part of an aquifer system. The top of an unconfined aquifer is the water table. A confined aquifer has at least one aquitard at its top and, if it is stacked with others, an aquitard at its base.

Figure 1 shows an example of an aquifer system in the lower Portneuf River valley. The diagram represents a cut-away perspective view of this system of multiple aquifers and is greatly exaggerated in its vertical scale to show some of the details. Several different aquifers occur in this valley. In the northern valley beneath Chubbuck and north Pocatello multiple confined aquifers are stacked on top of one another and separated by aquitards made of clay; the aquifers tapped by Chubbuck's municipal wells are in the fractured basalts of the eastern Snake River Plain.

In the southern valley Portneuf Gap to Red Hill the upper surface of the unconfined aquifer is the water table. How Does an Aquifer Work? An aquifer is filled with moving water and the amount of water in storage in the aquifer can vary from season to season and year to year.

Ground water may flow through an aquifer at a rate of 50 feet per year or 50 inches per century, depending on the permeability.