Home » Science & Nature » Environmental Science » What Really Lies Beneath: An Introduction to Groundwater

What Really Lies Beneath: An Introduction to Groundwater

© Danita LaSage

Earth is unique among planets we know of because of its abundance of liquid water. It’s been called the “water planet,” a fitting name since it’s about 70% water – enough water to form a solid cube 148 miles on each side. Life would not exist without water, nor would much of our civilization. It has at times been a source of international conflict, such as when Iraq sent troops to its border with Syria, who had reduced the flow of the Euphrates. Other countries in the Middle East, such as Egypt and Israel, have also threatened to use military force to protect their water interests.

In other parts of the world, however, we have yet to really feel what it means to lack water, and we tend to use it lavishly. For example, while it requires a mere 2 liters (about 2 quarts) of water each day for a person to survive, in the US we use about 6000 liters per person, per day. That includes more than just drinking, cooking, and watering our lawns, of course – irrigation accounts for more than 40% of water use in the US, and industry is another 38% or so. In the end, only about 20% of the 340 or so billion gallons of water we use daily is for personal household use.

That’s pretty amazing when you consider that 97% of the water on Earth is seawater. And of the rest, about 85% or so is locked up in glaciers and ice caps. In terms of ratios it means that if all the water on Earth were contained in 5 gallons (or 1280 tablespoons), most of the fresh water available to us would be represented by 8 tablespoons of groundwater buried under Earth’s surface. All the rivers, creeks, lakes, and reservoirs would be a mere 25 drops in the bucket.

That 8 tablespoons of groundwater is going to become increasingly important as the human population of the Earth continues to double every 30 years. Already 40% of water use in the US comes from groundwater, and a full 50% of our drinking water supplies come from the underground aquifers that store and transmit groundwater. Groundwater is also important as an agent of erosion (think of how caves form!) and as the source of baseflow to surface streams. (Have you ever wondered why rivers continue to flow long after the last rain? It’s because groundwater is seeping into the river bed, recharging the stream.)

The copyright of the article What Really Lies Beneath: An Introduction to Groundwater in Environmental Science is owned by . Permission to republish What Really Lies Beneath: An Introduction to Groundwater in print or online must be granted by the author in writing.