Aquifer

This is a contiguous formation of groundwater, held within some type of geologic structure.

Different underground substances hold water in different capacities. Solid rock, for example, might not have any space for water (though some rock is porous), while different types of soil are able to be saturated with water. An aquifer is where the underground substance and terrain allows water to consistently collect.

An aquifer is essentially a large “blob” of water stored under the surface of the ground, inside some substance, like an underground sponge. The boundaries of an aquifer are naturally vague as the surface of the Earth changes.

If you drill a hole into an aquifer, pressure will force water from the substance into the empty space of the hole. This is a well. If an aquifer gets saturated, water will eventually flow into surface water structures, like rivers, lakes, and springs. If an aquifer is depleted, this process happens in reverse, which is known as “recharging” an aquifer.

When an aquifer gets fill, water might “leak” out of the surface. This is a spring.

Some aquifers are known as “contained aquifers,” which mean they have a watertight seal partially on top of them – like a layer of rock. When this happened, water flowing into the uncontained portion can build pressure.

The study of aquifers is known as “hydrogeology.”

Why I Looked It Up

I’ve heard the word for years. It came up quite a bit in The Heat Will Kill You First: Life and Death on a Scorched Planet.

I never had a really clear definition of what one was. I thought that it was a pure space of water, like a cavern or something. While these apparently do exist, an aquifer is more commonly like a sponge – a substance that is saturated with water, from and to which water can flow.