Causes of groundwater depletion
Nature goes through a unique process to provide us with groundwater. The surface water that we can see is heated by the Sun and goes into the atmosphere as evaporation.
Water vapour then creates precipitation, water that falls from the sky as rain and snow. Once water falls from sky and onto the ground, it is absorbed into the Earth and is then stored as groundwater in aquifers.
Groundwater depletion background
Credit: National Geographic, groundwater is the water that seeps into the earth and is stored in aquifers—areas of soil, sand, and rock that are capable of holding liquid.
The water sits in between particles or in cracks and fissures. These saturated underground areas—some replenished by rain and snow, others not—can be found close to the Earth’s surface or hundreds of feet underground.
Threats to this underground source increase as population and development accelerate. Agricultural and urban runoff tainted with chemical pesticides and fertilisers seeps into groundwater sources but the biggest threat is simply withdrawing too much of this limited resource.
The overpumping of groundwater is causing water tables to fall across large areas of northern China, India, Pakistan, Iran, the Middle East, Mexico, and the western United States.
Causes of groundwater depletion: overuse
Groundwater depletion most commonly occurs because of the frequent pumping of water from the ground.
We pump the water more quickly than it can renew itself, leading to a dangerous shortage in the groundwater supply.
As a growing world with a population that continues to rise, the more we pump water from the ground at a rapid rate, the more difficult it is for the groundwater to provide us with the amount of water that we need.
We continuously pump groundwater from aquifers and it does not have enough time to replenish itself. Water flows freely through the saturated rocks known as aquifers. There are large and small aquifers, and they are the underground water reserves that absorb water and hold it, enabling us to pump it for use.
Causes of groundwater depletion: agricultural needs
The amount of water that aquifers hold is impressive and can provide us with billions of gallons of water per day.
However, whilst usage happens on a constant basis, replenishment often takes much longer to achieve.
Agricultural needs require a large amount of groundwater - a steady supply of water to meet crop and livestock requirements, linking food security directly to water security. Agriculture is the largest consumer of freshwater resources in the world - In the U.S. about 65% of groundwater is used for agricultural irrigation.
It’s frightening to think that there isn’t very much groundwater left when you consider how much water we use on a daily basis to support our population of billions and our personal lifestyles.
The availability of groundwater is steadily declining.
Causes of groundwater depletion: pollution
Groundwater contamination occurs when man-made products such as gas, oil, road salts and chemicals get into the groundwater and cause it to become unsafe and unfit for human use.
Materials from the land's surface can move through the soil and end up in the groundwater.
For example, pesticides and fertilisers can find their way into groundwater supplies over time.
Road salt, toxic substances from mining sites, and used motor oil also may seep into groundwater.
In addition, it is possible for untreated waste from septic tanks and toxic chemicals from underground storage tanks and leaky landfills to contaminate groundwater.
Atmospheric contaminants in the air and from aerosols have an impact on groundwater availability through the constant actions of the water cycle.