Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Understanding the Caplina/Concordia aquifer system through a hydrogeological model (Atacama Desert : Peru/Chile)

Auteur : Narváez Montoya, Christian Felipe

Etablissement de soutenance : Instituto de Tecnológico de Estudios Superiores de Monterrey (ITESM)

Grade : Master of Science In Engineering Science 2021

Résumé
The Caplina/Concordia transboundary coastal aquifer system, located in the Atacama Desert, is the primary source of water supply for domestic use and irrigation for La Yarada-Los Palos (Peru) and Concordia (Chile) agriculture districts, and to a lesser extent, for Tacna province public supply use (Peru). Despite the scarce amount of rainfall (< 20 mm/year) in the area and the limited recharge coming from the Andean highlands, this transboundary aquifer system has been overexploited mainly for agriculture since before the 2000s in the Peruvian side. Consequently, this has caused groundwater depletion and seawater intrusion. In this study, comprehensive hydrogeological information was integrated to understand the aquifer system’s behavior and the effects to which it has been subjected to groundwater overexploitation. To that end, a 3D hydrogeological framework was developed using the LEAPFROG software and a density-dependent groundwater flow model was generated in FEFLOW software, which was adjusted with Monte Carlo analysis and conventional automated calibration. Finally, eight scenarios, considering various water resource management options proposed by the authority and potential climatic trends (CMIP6), were simulated from 2020-2040 period. The results showed that between 2002-2020, the increase in the seawater wedge and the average groundwater level decline were 216.29 hm3/year and 6.62 m, respectively. It is expected that the depletion will continue with a groundwater level decline between 4.51 and 7.53 m and an increase in the seawater wedge between 1120.20 hm3/year and 1175.47 hm3/year for the forecast period. The study concludes that the aquifer system will remain unsustainable for the next 20 years, regardless of the selected scenarios, and suggests that any mitigation measure requires the participation of stakeholders from Peru, Chile, and Bolivia.

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