In this article you will find many facts about groundwater, the most abundant and important natural freshwater resource on the planet that is found below the surface.
What is groundwater?
Groundwater is that natural water resource that is trapped or reserved under the earth’s surface in rock formations that are in the earth’s crust and are known as aquifers, its importance lies in the fact that it represents more than 94% of fresh water. suitable for human consumption.
Groundwater distribution
Did you know that the largest volume, percentage or amount of fresh water (water suitable for human consumption) is from groundwater?
This means that the underground water is of vital importance for future generations and for this reason we must begin to take care of it.
To understand, around 70% of the planet’s surface is water, of this 70%, around 97.5% is salt water (salt water is not suitable for human consumption), and only 2.5% is fresh water.
Of this fresh water, 85% is in the glaciers, therefore it is water that cannot be consumed or used because it is frozen, 14% is groundwater and almost 1% is rivers, lakes, lagoons and bodies of surface water.
However, of all the fresh water that can be consumed (without glaciers and snow), 94% is groundwater and only 4% are rivers, lakes, and surface water bodies, which in turn are fed by groundwater.
If we put all the fresh water that we can consume in relation to the total water in the world as a percentage, it barely reaches 0.025%, for all living beings, it is so little water.
All the mentioned data is found in the following table.
| fresh water in the hydrosphere | Volume of water in km3 | Percentage | thawed fresh water |
| glaciers | 24000000 | 84,945 | 0 |
| Underground water | 4,000,000 | 14,158 | 94.05 |
| Lakes and lagoons | 155000 | 0.549 | 3.64 |
| Humidity of floor | 8300 | 0.294 | 1.95 |
| water vapor in the atmosphere | 14000 | 0.049 | 0.33 |
| river water | 1200 | 0.004 | 0.03 |
| Total | 28253200 | 100 | 100 |
What is the importance of groundwater?
Although hidden from view, large amounts of water exist below the ground in the cracks and pore spaces of crustal rocks.
Like drinking water
Groundwater occurs almost everywhere below the Earth’s surface and is a major source of water throughout the world.
It is a valuable natural resource that provides about half of our drinking water and is essential for agriculture and industry.
It can be extracted by building wells, very similar to oil wells.
In the past, very deep and wide wells were built and groundwater was extracted with a rope and a bucket. In fact, in areas of the planet with extreme poverty and low resources they continue to do so, but in large cities, it is done with wells.
In surface waters
In addition to human uses, groundwater plays a crucial role in maintaining the flow of rivers, especially during prolonged dry periods. Additionally, many ecosystems depend on groundwater discharge into streams, lakes, and wetlands.
Groundwater is therefore a form of storage that sustains streams during periods when it does not rain. When we see water flowing in a river during a dry period, it is rainwater that fell sometime before and was stored underground and is now coming out from aquifers.
It is the largest freshwater reservoir
Groundwater is one of our most important and widely available resources, yet people’s perceptions of the subsurface environment from which it comes are often unclear and incorrect.
| Fresh water in the hydrosphere | Volume of water in km3 | Percentage | thawed fresh water |
| glaciers | 24000000 | 84,945 | 0 |
| Underground water | 4,000,000 | 14,158 | 94.05 |
| Lakes and lagoons | 155000 | 0.549 | 3.64 |
| Humidity of floor | 8300 | 0.294 | 1.95 |
| water vapor in the atmosphere | 14000 | 0.049 | 0.33 |
| river water | 1200 | 0.004 | 0.03 |
| Total | 28253200 | 100 | 100 |
Taking into account the entire hydrosphere, or all the water on Earth, only about six-tenths of 1 percent occurs underground.
However, this small percentage, stored in the rocks and sediments below the Earth’s surface, is a huge amount.
When the oceans are excluded and only freshwater sources are considered, the importance of groundwater becomes more apparent.
Clearly, the largest volume occurs as glacial ice.
Second in rank is groundwater, with just over 14 percent of the total.
However, when ice is excluded and only liquid water is considered, more than 94 percent of all fresh water is groundwater.
Undoubtedly, groundwater represents the largest freshwater reservoir that is available to humans. Its value in terms of economy and human well-being is incalculable.
Geological importance
Geologically, groundwater is important as an erosive agent. The dissolving action of groundwater slowly removes rock, allowing surface depressions known as sinkholes (KARST) to form, as well as the creation of underground caverns.
Where is groundwater found (Sources)?
Water is an element that circulates or moves in various places on planet earth and this is known as the hydrological cycle.
Of the water that falls onto the earth’s surface, some evaporates directly into the atmosphere, some is trapped in glaciers, and some becomes runoff that enters a network of streams, rivers, and lakes that flow into the sea.
However, there is a percentage that sinks or seeps down, through a process called infiltration, into the ground.
In effect, the upper part of the crust behaves like a giant sponge that can absorb water.
Of the water that infiltrates, some only runs down to the soil and wets the surfaces of the grains and organic material that make up the soil.
This water, called soil moisture, then evaporates back into the atmosphere or is absorbed by plant roots and transpired back into the atmosphere.
But some of the water sinks deeper into sediment or rock, and together with the water trapped in the rock at the time it formed, they form the underground water.
The underground water it flows slowly underground from a few months to tens of thousands of years before returning to the surface to pass once more to other reservoirs in the hydrological cycle.
Therefore, groundwater resides in, or accumulates in, porous rocks below the earth’s surface, known as aquifers or groundwater reservoirs. Learn about aquifers by clicking here.
How do you extract or exploit groundwater?
Now that we know that this water is found below the surface in rock formations known as aquifers, we need to know how the water can be extracted from those rocks.
In large cities and areas where current technology can be applied, groundwater can be extracted with the help of mechanical wells, very similar to the wells that extract oil but are smaller and not as expensive.
In areas where there are few economic resources, the technique of making water wells by hand continues to be applied, that is, they are built in such a way that they are deepened until they reach the water level and then the water is extracted with the help of a bucket., a rope and a pulley.
What is the quality of groundwater?
Now that you know that water accumulates underground, you can surely imagine that it has a lot of “dirt” or is “dirty” or contaminated, but believe it or not, groundwater is completely crystal clear, in fact, big companies like COCA COLA use it for their drinks.
Does it sound like “bottled water”, “Sparkling water”, Thessaly, these drinks are made with groundwater.
In fact, the commercial distribution of bottled groundwater (spring water) has become a significant business throughout the world.
Much of the world’s groundwater is crystal clear and pure enough to drink directly from the ground.
Rocks and sediments are natural filters capable of removing suspended solids: these solids get trapped in small pores or adhere to the surfaces of clay grains.
But dissolved chemicals, and in some cases methane, can render some groundwater natural.
Natural contamination of groundwater
Salt pollution
For example, groundwater that has passed through salt-containing soil layers may become salty and unsuitable for irrigation (in agriculture) or human consumption.
Hard water
Groundwater that has passed through limestone or dolomite contains dissolved calcium (Ca2O) and magnesium (Mg2O) ions; This water, called hard water, can be a problem because carbonate minerals precipitate out of it to form a “layer” that clogs pipes.
Also, using this water to wash clothes can be difficult because the soap will not foam.
For iron and iron oxides
The underground water that has passed through iron-bearing rocks may contain dissolved iron oxide which precipitates to form rust stains.
By sulfur and hydrogen sulfide
Some groundwater contain dissolved hydrogen sulfide, which comes out of solution when groundwater rises to the surface; hydrogen sulfide is a poisonous gas that smells like a rotten egg.