The Guarani Aquifer, located beneath the surface of Argentina, Brazil, Paraguay, and Uruguay, is one of the world's largest aquifer systems and is an important source of fresh water. Named after the Guarani people, it covers 1,200,000 square kilometres (460,000 sq mi), with a volume of about 40,000 cubic kilometres (9,600 cu mi), a thickness of between 50 metres (160 ft) and 800 metres (2,600 ft) and a maximum depth of about 1,800 metres (5,900 ft). It is estimated to contain about 37,000 cubic kilometres (8,900 cu mi) of water (arguably the largest single body of groundwater in the world, although the overall volume of the constituent parts of the Great Artesian Basin is much larger), with a total recharge rate of about 166 km³/year from precipitation. It is said that this vast underground reservoir could supply fresh drinking water to the world for 200 years. However, at closer inspection, if the world population were to stay at an equilibrium of about 6.96 billion, not even taking into account that babies need less water than grown adults, this figure reaches 1600 years, allowing about 9 liters per day per person. Due to an expected shortage of fresh water on a global scale, which environmentalists suggest will become critical in under 20 years, this important natural resource is rapidly becoming politicized, and the control of the resource becomes ever more controversial.
Geology of the aquifer
The Guarani Aquifer consists primarily of fluvial sandstones of the Piramboia Formation and aeolian sandstones of the Botucatu Formation, which were deposited during the Triassic and Jurassic periods. Over 90% of the total area is overlain by early Cretaceous basalts of the Serra Geral Formation. The basalt's low permeability allows it to act as an aquitard, providing a high degree of containment. This greatly reduces the rate of infiltration and subsequent recharge, but also isolates the aquifer from the vadose zone, subsequent surface-associated losses due to evaporation and evapotranspiration, and potential contamination.
Research and monitoring of the aquifer in order to better manage it as a resource is considered important, as the population growth rate within its area is relatively high — resulting in higher consumption and pollution risks.
The countries over the aquifer are also the original four Mercosur countries.
|Wikimedia Commons has media related to Acuífero Guaraní.|
- Official Site for the book about the Aquifer, by Nadia Rita Boscardin Borghetti, José Roberto Borghetti and Ernani Francisco da Rosa Filho (in Brazilian Portuguese)
- Conference «The Management of the Guarani Aquifer System: An Example of Cooperation»