Aquifers: Pollution and Depletion

Water makes up for about 70% of Earth’s surface – this is a well-known fact. What is often overlooked is the fact that out of all that water, only 2,5% accounts for fresh water. The larger amount of fresh water remains solidified (ice) or trapped underground and is often accessed using Aquifers. This means that only 0,3% of fresh water can be found in rivers, lakes, etc.

What are Aquifers

Since the earliest times, humans learned to artificially excavate water from underground reservoirs called aquifers. To simplify, people would build wells to pump out drinkable water. Aquifers are essentially huge storehouses of water that can be found under Earth’s surface, trapped in the empty spaces between the rocks. Groundwater can be used for drinking, as well as agricultural irrigation or central heating.

Aquifers can be found under most land areas of the planet, their depth, however, varying. The degree to which we can exploit these water sources is determined by how deep underground they are situated. The deeper they are, the harder and costlier the excavation is. Needless to say, as a civilization, we largely depend on the existence of these aquifers.

Having said that, it is sad to acknowledge that very little is being done by governments, authorities and the major industries to protect the aquifers. Someone might wonder what a body of water underground needs protecting from. The answer is that aquifers are often exposed to different types of pollution and subject to slow, but inevitable depletion.

Water Depletion

Groundwater depletion is a term most often used to describe the decline in water levels as a consequence of the intensified pumping of water from the aquifers. Land areas, where drinkable water is not available in lakes, rivers, and springs, depend solely on groundwater as a water supply. Most of these areas are experiencing groundwater depletion at this moment.

If an underground water source isn’t exhausted and replenished at the same rate, it could lead to a local well drying up and leaving the entire nearby population without a steady and secure water supply.

Another consequence, that we are currently witnessing, is the decrease of the water table’s height. Lakes, rivers, and streams interact with aquifers to different degrees, depending on the local geological and hydrological conditions. Depletion can change the way water flows between the aquifers and the surface water bodies, which leads to the lowering of the water level. If the level decreases to a certain point, wetland vegetation and wildlife is also influenced because they need a certain depth to be maintained in order to survive.

What is more, the lowering of the water level also means that the pump would have to go deeper. This increases the cost of the equipment used for drilling and extraction, which inevitably calls for a higher price of water for the users. Groundwater depletion can cause a decrease in the quality of water. Usually, salt water and sweet water are successfully separated during this process, however unbalanced pumping could cause for the two of them to mix.

When the space between the underground rocks is completely depleted of water, the land above it can collapse or compact. This effect is called land subsidence and although it doesn’t happen so often, it represents a dangerous repercussion of uncontrolled water pumping.

How to Replenish Water

Groundwater is gradually replenished by precipitation – the product of water vapor condensing between the rocks. However, the pace of this process is not nearly fast enough to make up for the amount of water that we exhaust. In order to reduce the consequences to the highest extent possible, we need to balance the amount of water we pump from these aquifers. Unfortunately, our demands for water are high and cannot withstand the time period needed for the aquifer to refill through condensation.

One way to reduce the depletion is reinjection. Groundwater is sometimes used as a secondary liquid because it absorbs Earth’s heat and can reach an average temperature of 30℃. This means that it is extracted from the Earth, lead to a special heat exchanger where it is used to warm up another (work) liquid – water or antifreeze, that is afterward used in heating systems, industries, agricultural greenhouses, etc. When the groundwater has warmed up the working liquid, it is, more often than not, thrown out as waste. This method, however, has seen some change in the past years, since used groundwater is reinjected with a special tube back to the aquifer, where it is again warmed up to a certain temperature and prepared for repeated use.

Pollution

Groundwater pollution is caused by releasing chemicals, waste, oil, gasoline or any other byproduct of human activity in the ground. These pollutants are absorbed by the soil and find their way into the aquifers underground, rendering them unfit to use. Groundwater contamination is almost always a consequence of human activity, although it’s possible that it sometimes occurs naturally – due to the presence of an unwanted or harmful element.

Records show that consuming contaminated groundwater causes different health issues, depending on the type of contamination. Users have been known to suffer from hepatitis, dysentery, poisoning and even some types of cancer. To prevent these issues and to keep water consumers safe, we must understand what exactly pollutes our water resources and how to stop that.

In most cases, pollutants are different kinds of pathogens, nitrate or VOCs (Volatile Organic Compounds). These pollutants can stem from different sources on Earth’s surface.

Pollution Origins

Septic systems, especially in highly urban areas, are designed to safely and gradually dispose of human waste by leading it underground at a harmless rate. Mistakes and errors in the septic system’s design can lead to leaking and releasing pollutants into the ground, which will inevitably end up in our water supply. Households and office buildings that aren’t connected to the septic system and dispose of their waste on-site can also pose a threat.

Landfills are places where solid waste from an entire urban area or industrial unit is disposed of. In ideal scenarios, this waste is sorted and taken away for recycling. However, this rarely happens. The waste is either burned or buried underground, both options being catastrophic for the environment. In the case where landfill waste is buried, all of the pollutants and harmful materials contained can leach into the groundwater through precipitation.

Storage tanks are large structures made to store oil, petroleum or gasoline. They can be built either above or underground. Regardless of their position, they are subject to extreme corrosion because of the chemicals they contain. When corrosion wears out the tank’s walls and leaks through the hole into the ground, it contaminates the existing groundwater and causes serious problems.

Pesticides and fertilizers are used in large amounts for crops production. When it rains, these chemicals seep into the soil and contaminate the groundwater. They can stay in the ground for months before they flow into the groundwater. Another threat is animal waste from feedlots that are not regulated and disposed of properly.

Hazardous waste (oils, paint, swimming pool chemicals, photographic materials, medical waste) is usually collected from municipalities by a certified handler. Unfortunately, a good amount of hazardous waste from households and industrial processes ends up in landfills or septic systems.

Prevention of Groundwater Pollution

In most cases, groundwater pollution can be completely prevented. Most countries have a number of regulations to ensure the safety of the aquifers. However, a lot of the responsibility is left to us as individuals to treat our waste with more care and caution. Companies who produce waste often have to follow a special set of rules – filtering waste, using special equipment to prevent leaks, etc…

There are multiple ways to remediate contaminated groundwater, such as pumping out the contaminated water in order to treat it and reinject it, or containing it and preserving the uncontaminated portion. Unfortunately, these are not long-term solutions and prevention has proved to be a safer option.

Groundwater makes up for about 20% of the world’s water supply. Its protection and regulation continue to present a big environmental question and scientist are still working on new and improved answers. No matter how many technical solutions we come to in the future, each one of us should take responsibility to implement them and contribute to the preservation of our water resources.

In the end, water is a vital substance that provides for all life forms on Earth, including ours. The continuous pollution and depletion of the aquifers should scare us, but more importantly, motivate us to preserve what is left of them.

About Martina Blazheska

Martina is a mechanical engineering student from Skopje, Macedonia. When she’s not drowning in homework, she likes to write articles. Her favorite things to write about are feminism, social justice, science, ecology and travel. Martina is fascinated with the influence of social media and hopes that her words can make a difference, no matter how big or small.

All Articles