What is groundwater?
The Earth is 70 % water. However, only 3% of this water is freshwater. Much of this freshwater is frozen in glaciers, you will find some of the water in rivers and streams, and almost 30% of this freshwater is groundwater.
But What is groundwater? Groundwater is water that finds it way between the gaps of rocks and sediments underground.
As the water seeps into the ground it may find it’s way into an aquifer. Aquifers are underground rock layers saturated with groundwater. An aquifer is not an underground river but large porous layers of rock.
For example, the Floridan aquifer covers almost the entire state of Florida and is 100,000 square miles. Think of an aquifer like a huge underground sponge that soaks up water that falls to the surface of the earth.
If you grabbed a shovel and started digging straight down you may strike water.
The first water you strike is the water table. Below the water table, the rock may be completely soaked. This is called the saturation zone, The rocks and sediment above the saturation zone is the unsaturated zone.
How does the water end up in the ground?
When it rains or snows some of the water moves down into the ground. If this water moves deep enough it can stay their for a long time.
Like thousands of years.
However, not all of the groundwater stays underground. Much of the surface water comes from groundwater and aquifers. If the ground dips below the water table the groundwater will flow to the surface and may create a body of surface water.
Groundwater can also flow out of the ground and create a stream. This is called a spring.
However, some groundwater is so deep it is very difficult to get to. These bodies of groundwater are called confined groundwater.
Humans depend on groundwater for drinking water and growing crops.
The groundwater can be reached by digging a well There are thousands and thousands of well throughout the world.
15 Facts about Groundwater
- Groundwater is water that seeps into the ground and is stored in porous rock.
- Permeability is a measure of how easily water can flow through rocks and minerals.
- The storage space of an aquifer is measured by porosity.
- Recharge is when surface water trickles down into the ground and reaches the water table and enters an aquifer.
- Aquifers can be huge. The Ogallalla aquifer, which underlies portions of eight states.
- Aquifers are important sources of drinking water. For example,
- the Kirkwood–Cohansey Aquifer, is located under the Pine Barrens of southern New Jersey, contains 17 trillion US gallons of some of the purest water in the United State.
- The first water you reach when you dig down into the Earth is the water table. It is the upper surface of the groundwater.
- A confined aquifer has layers of impermeable material both above and below the aquifer.
- Sandstone, conglomerate, fractured limestone and unconsolidated sand and gravel. along with basalts make good aquifers.
- Agriculture accounts for almost 70% of groundwater use.
- A cup of gravel has a greater porosity than a cup of sand.
- An aquifer is filled with moving water and the amount of water in storage in the aquifer can vary from season to season and year to year.
- The disposal of waste at landfills, by septic tanks, or storm drain wells can have a negative impact on the quality of ground water in an aquifer.
- The Ogallala aquifer in central United States is the largest aquifer in the United States.
- Two billion people use aquifers that are filled with groundwater as a water source.
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