Groundwater Basics

Millions of cubic miles of water exists in the ground. You can't see it, but not only is it there, it is always moving around -- mostly downward, but also horizontally. Moving groundwater helps keep rivers full of water and allows for people to draw out water via wells. Moving groundwater is an important part of the water cycle.

Naturally, the water running in rivers comes from precipitation that runs off the landscape into the river. But since precipitation also seeps into (and moves) into the ground, you don't often consider that a significant amount of the water flowing in rivers comes from water in the ground seeping back "up" into the river from below.

Wells are extremely important to all societies. In many places wells provide a reliable and ample supply of water for home uses, irrigation, and industries. Where surface water is scarce, such as in deserts, people couldn't survive and thrive without groundwater, and people use wells to get at underground water.

Artesian water is really not different from other groundwater, except for the fact that it flows to the land surface because pressure in the rocks underground force it to the surface. But, having water flow to the surface naturally is a handy way to tap groundwater resources.

Groundwater decline is a real and serious problem in many places of the Nation and the world. When rainfall is less than normal for several weeks, months, or years, the flow of streams and rivers declines, water levels in lakes and reservoirs fall, and the depth to water in wells increases.

"Water dowsing" refers in general to the practice of using a forked stick, rod, pendulum, or similar device to locate underground water, minerals, or other hidden or lost substances, and has been a subject of discussion and controversy for hundreds, if not thousands, of years.

Yes, land subsidence is responsible for you getting a little dizzy when you look at the first picture in the banner above, the one of a line of buildings. The land these buildings sit on has fallen and compacted because large amounts of groundwater have been withdrawn from the aquifers below ground. Land subsidence is a human-induced event.