Groundwater is an important natural resource, but like many of our other resources, it’s affected by the surrounding environment and human activities. In this video lesson, you’ll learn about some of the environmental problems associated with groundwater and why groundwater is especially vulnerable to them.
Groundwater Is Vulnerable
Groundwater is one of our most important natural resources. It provides us with much of the water that we use for drinking water, household uses, crop irrigation, and many other things. In fact, over 1/3 of Earth’s population relies on groundwater for its needs, including 99% of the rural population in the U.S.
But, just because it’s underground doesn’t mean that groundwater is safe from many of the same environmental issues that surface water faces. In fact, being underground makes it more vulnerable to environmental issues because we can’t easily access it for testing, regulating, and cleaning. Groundwater also moves around a lot, not only underground, but also as a source of discharge into Earth’s streams, rivers, lakes, and oceans.
Pollution is one of the main environmental issues that groundwater faces. Groundwater pollution comes from many sources, and this happens when harmful substances get into the soil. When it rains, water washes over the substances in the ground and carries them down into aquifers below, much like hot water does when you pour it over a filter full of coffee.
Agriculture pollutes groundwater as fertilizers, pesticides, and herbicides soak into the ground. Nitrates from the fertilizers are especially dangerous in drinking water because they’ve been linked to various cancers, miscarriages, and birth defects. Manufacturing industries are also major culprits. There are often many different toxic chemicals involved in manufacturing the products that we use, and if not properly disposed of, they may leach into the ground, soaking down into the groundwater below. Underground storage tanks, like septic tanks, can also leak sewage waste, oil, and toxic chemicals into the ground.
Groundwater can be depleted much faster than surface water because aquifers take a very long time to refill. Groundwater is pumped from wells for drinking water, but it’s also pumped for large-scale uses like agricultural irrigation. This water is removed from the ground at a very fast rate and then moved to another location to water large areas of crops. The water doesn’t get returned to the ground in the same place, so even as it slowly sinks back down into the soil, it doesn’t go directly back into the aquifer it came from.
You can think of the world’s aquifers like a bank account. You can take out as much as you like as long as you’re making deposits that cover your withdrawals. Unfortunately, we’re not depositing nearly as much water as we’re withdrawing, so our account is quickly dwindling down to a dangerously low balance.
Overdrawing groundwater not only means that we may run out of water to pump, but it also allows saltwater to intrude into aquifers along coastal areas. Have you ever accidentally swallowed some sea water? Imagine that your aquifer has become salty from ocean water intruding. Still want to use it for your drinking water? Probably not!
Overdrawing groundwater also leads to another problem called subsidence. This is when the ground sinks down to fill the space below. You can think of groundwater like an inflated balloon below ground. This balloon is filling up some space below the surface, and then you quickly let the air out of it. Everything around where that balloon was will sink in to fill the newly opened space.
The same thing happens with the land around groundwater when water is removed too quickly. Subsidence can occur as sudden small holes, like the sinkholes we learned about in another lesson, or it can occur over a large area like an entire city. In fact, Mexico City, one of the largest cities in the world, has slowly sunk more than 33 feet because of subsidence. In this city, you’ll find buckled streets, buildings that tilt and lean (much like the Leaning Tower of Pisa), and broken underground pipes.
Groundwater is very important to us, but it faces several environmental problems that put both us and the environment at risk. Because groundwater is out of sight, problems often go unseen, unmonitored, and untreated. Groundwater pollution is a serious problem because many people get their drinking water from wells. Agriculture, manufacturing, and underground storage tanks are just a few of the harmful substances that enter the ground and percolate down to aquifers below.
Overdrawing groundwater is much like overdrawing your bank account. Unless you put in more than you spend, you’ll quickly find that you’ve got nothing left! Aquifers take a very long time to refill and we’re pumping groundwater out much faster than it is going back in. Overdrawing aquifers along coastal regions also allows sea water to intrude, making that water unavailable for drinking.
Subsidence, which is when the land sinks down due to overdrawing groundwater, can come suddenly as sinkholes or can slowly wreak havoc on large areas. Like deflating the space below, pumping too much groundwater leaves a void that gets filled by the ground above slowly sinking into it. Many cities are facing this problem, which can destroy buildings, roads, and underground pipe systems as the land falls in.
After reviewing this lesson, you’ll have the ability to:
- Explain why groundwater is more vulnerable to environmental concerns
- Describe several environmental problems that negatively affect groundwater
- Summarize how these environmental issues with groundwater can damage cities and harm people