Pica Aquifer ( es, acuífero de Pica) located in

Tarapacá Region The Tarapacá Region ( es, Región de Tarapacá, ) is one of Chile's 16 first-order administrative divisions. It comprises two provinces, Iquique and Tamarugal. It borders the Chilean Arica and Parinacota Region to the north, Bolivia's Oruro D ...

of northern Chile is one of the most important

aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...

s of

Atacama Desert The Atacama Desert ( es, Desierto de Atacama) is a desert plateau in South America covering a 1,600 km (990 mi) strip of land on the Pacific coast, west of the Andes Mountains. The Atacama Desert is the driest nonpolar desert in the ...

. The water of the aquifer is tapped by a system of underground aqueducts known as

puquios Puquios (from Quechua ''pukyu'' meaning source, spring, or water well) are ancient systems of subterranean aqueducts which allow water to be transported over long distances in hot dry climates without loss of much of the water to evapora ...

to irrigate the

oases In ecology, an oasis (; ) is a fertile area of a desert or semi-desert environment'ksar''with its surrounding feeding source, the palm grove, within a relational and circulatory nomadic system.” The location of oases has been of critical imp ...

of Pica and

Matilla Matilla is a Chilean village and oasis in the interior of Atacama Desert. It lies four kilometers southwest of the oasis town of Pica. As of 2017 Matilla had 380 inhabitants and 217 homes. It host underground aqueducts in various states of decay. ...

. The uppermost part of the aquifer is within loosely consolidated

alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...

and aeolian

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...

s deposited in the

Quaternary period The Quaternary ( ) is the current and most recent of the three period (geology), periods of the Cenozoic era (geology), Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spa ...

. The recharge zone of Pica Aquifer is estimated to lie between ~3,000 and 4,000 meters

above sea level Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as ''orthometric heights''. The comb ...

. As nearby oasis

Puquio de Núñez Puquio de Núñez is a small oasis and orchard in the Atacama Desert of Chile. The oasis is irrigated by an underground canal, a puquio tapping Pampa del Tamarugal Aquifer. Puqui de Núñez lies about 10 kilometers south of the nearby oases of Matil ...

taps the

Pampa del Tamarugal Aquifer Pampa del Tamarugal Aquifer ( es, acuífero de la Pampa del Tamarugal) located in Tarapacá Region of northern Chile is one of the most important aquifers of Atacama Desert. At the oasis of Puquio de Núñez the water of the aquifer is tapped by ...

it is thought that the hydraulic divide between the aquifers of Pampa del Tamarugal and Pica should be between Puquio de Núñez and Matilla. It is not known if the waters of Pica Aquifer flow into Pampa del Tamarugal Aquifer as these two aquifers are separated by the Longacho fault line. While this fault may deviate and block part of the flow a 2012 study showed a

hydraulic gradient Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22. It is usually measured as a liquid surface elevation, expressed in units of length, ...

from Matilla to west suggesting that water from Pica Aquifer flow into Pampa del Tamarugal Aquifer.

References

Aquifers in Chile Geology of Tarapacá Region Atacama Desert Springs of Chile Water supply and sanitation in Chile {{Tarapacá-geo-stub