aquifer is a underground geological formation capable of storing water, forming huge underground lakes.
For the formation of an aquifer, the existence of porous rocks or rocks with characteristics permeable, capable of absorbing rainwater and infiltrating underground, serving as a source of supply for the aquifers.
Aquifers also help in the course of surface waters, such as lakes, springs, springs and rivers, keeping them stable, as all excess rainwater is absorbed by them.
There are two main types of aquifers, which vary according to the form of water storage.
Free or groundwater aquifers
Free or groundwater aquifers are formed by permeable rocks, where the base is constituted by an impermeable or semi-permeable layer.
These types of reservoirs are partially covered by water, the top being limited by a surface that does not contain water, called the "phreatic surface".
Rains determine the water level of these reservoirs, which are considered the most common and explored.
Confined or artesian aquifers
US confined aquifers, both the base and the roof are formed by impermeable rocks, and totally saturated with water, with no space for atmospheric pressure.
The water is trapped under a pressure greater than atmospheric pressure, that is, when the rock is drilled to extract water (an artesian hole), it gushes out.
These aquifers are exploited to create artesian wells in homes.
Guarani Aquifer
O Guarani aquifer it's the largest freshwater reservoir in the world, with about 1.2 million square kilometers, covering four countries in South America: Argentina, Brazil, Paraguay and Uruguay. However, 70% of the aquifer is in Brazilian territory.
Estimates say that there are about 45,000 cubic kilometers of fresh water in this reservoir, which would support about 400 million people for a year.
The Guarani aquifer is also known as the "Mercosur Giant Aquifer".
Alter do Chão Aquifer
The Alter do Chão aquifer or Grande Amazônia aquifer is an underground freshwater reserve that covers the Brazilian states of Pará, Amazona and Amapá.
This is the largest aquifer in the world by volume of water, with about 86,000 cubic kilometers, enough to sustain the entire world population for more than 100 times.
Even though it is smaller than the Guarani aquifer (considered the largest in the world in terms of extension), the Alter do Chão aquifer has twice the volume of water.
