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Groundwater Characteristics in Paraguay

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Regarding underground water resources, Paraguay has three major groundwater extraction aquifers within the La Plata Basin: firstly, the Patiño Aquifer located in the central part of the country; then the Misiones Aquifer, a component of the Great Guaraní Aquifer System shared with Brazil, Argentina, and Uruguay; and the Yrendá Aquifer in the Central Chaco, a component of the Great American Chaco, shared with Bolivia and Argentina, where in the latter country it is called the Toba Aquifer (Monte Domecq and Báez Benítez, 2007).

Paraguay’s aquifer systems can be classified according to their lithological nature and hydraulic properties into (Godoy and Paredes):

  • Aquifers permeable due to intergranular porosity, and
  • Aquifers permeable due to rock fracturing, conditioned by geological structures and karstification processes

Within the system of aquifers permeable due to intergranular porosity are:
*Chaco Yrenda Aquifer
*Patiño Aquifer
*Misiones Aquifer
*Caacupé Aquifer

Among these aquifers, those of greater importance due to their strategic location, dimensions, and utility are: the Guaraní Aquifer and the Patiño Aquifer.

– Guaraní Aquifer:

Map showing the Guaraní Aquifer System (Sistema Acuífero Guaraní) across Brazil, Paraguay, Argentina, and Uruguay with marked regions and water sources

Montaño et al. mention that the Guaraní Aquifer System (GAS) represents one of the most important freshwater reserves in the world. It is a transboundary aquifer with an area of 1,200,000 km2 shared by four countries: Argentina, Brazil, Paraguay, and Uruguay. It consists of a set of sandy rocks located below ground level that hold water in their pores and fissures. These rocks were deposited there between 245 and 144 million years ago (Guaraní Aquifer System – ICAA).

The water found in the confined area is used to meet the demand of thermal centers and could be used for industrial purposes. The outcrop area is important as a high-quality water source for public supply to medium and large cities. In recent decades, the use of groundwater in both regions has grown exponentially, mainly in the outcrop area (Montaño et al. n.d.).

– Patiño Aquifer:

Detailed map of Paraguay highlighting the Patiño Aquifer and Rio Paraguay, with various cities and towns marked, including Asunción, Limpio, Luque, and San Lorenzo
Source: Báez et al. 2014
The Patiño Aquifer is located in the Eastern Region of Paraguay. It is an unconfined aquifer covering 1,173 km2, situated beneath Asunción, the surrounding cities that are part of the Central department, and part of the Paraguarí department (Báez et al. 2014). Arraval and Álvarez (2019) mention that the existing lithology in the aquifer gives it specific hydraulic characteristics, showing it to be an aquifer with moderate to low permeability, configuring a poor, somewhat permeable aquifer. Piezometric levels show flow behavior that broadly follows the topographic surface and surface flows. The main recharge occurs in the high areas of the basins. Hydraulic gradients show a connection with the main courses, and most drain the aquifer, becoming a natural discharge zone.
Map showing Paraguay's water resources, including the Rio Apa, Lago Ypacaraí, Lago Ypoá, and aquifers such as Patiño, Yrenda, and Guaraní, with descriptions of water availability and quality
Source: Hidricos_triptico_37,3x26,4cm (mades.gov.py)

REFERENCES

Arraval and Álvarez (2019):
https://publications.iadb.org/publications/spanish/document/Estudio_de_recursos_h%C3%ADdricos_y_vulnerabilidad_climática_del_acu%C3%ADfero_Patiño_es.pdf

Báez Lovera, LV; Villalba Cardozo, C.; Nogues Peña, JP. 2014. Mapping the Vulnerability and Risk of Groundwater Contamination in Greater Asunción (online). National University of Asunción, Asunción, PY. Consulted Apr 19, 2017. Available at 139 http://opengeo.pol.una.py/descargas/Informe%20Final%20Politecnica%20INV20.pdf

Godoy and Paredes:
https://www.geologiadelparaguay.com.py/Acuiferos-Potenciales-del-Paraguay.pdf

Monte Domecq and Báez Benítez, 2007: CA0443ES.pdf (fao.org)
Guaraní Aquifer System – ICAA: https://icaa.gov.ar/sistema-acuifero-guarani/