What is Groundwater?
Groundwater is the hidden water under our feet. When many people think of a water source, they think of lakes, rivers and streams; in other words, surface water. However, of all the usable freshwater in the world, approximately 97 percent of it is ground water. It is very necessary for life.
For instance, during the drought in Cape Town when the entire city was threatened with “Day Zero” when we would have to turn off our taps, schools, hospitals and private homes dug boreholes to access the groundwater. This enabled the city to make it push back Day Zero until the rains came. However, the danger is that if groundwater is removed in an unsustainable manner, then the water table drops and trees and plants will then begin to die. There is also a danger of using water resources that future generations will need desperately as rain reduces with climate change.
Where is groundwater found?
It is the water found underground in the cracks and spaces in soil, sand, and rock. It is stored in and moves slowly through geologic formations of soil, sand and rocks called aquifers. Different types of rocks and dirt can contain different amounts of water.
The saturation zone is the portion of the soil and rock that is saturated with water, while the unsaturated zone is the portion of the soil and rock that is not saturated. The top of the saturated zone is called the water table. When it rains, the water infiltrates the soil and percolates downwards until it reaches the water table. Some types of soils allow more water to infiltrate than others. Permeable surfaces, such as sand and gravel, allow up to 50 percent of precipitation to enter the soil.
How can we protect out groundwater and aquifers?
Remember that pollution will seep down into the groundwater, so we need to be careful where we throw oil or paint etc. The aquifers also need to recharge, so we need to protect our wetlands and make sure that we do not pave over open spaces. But rather use gravel.