Hydrogeological functioning of the aquifer of the nucleus of the Atacama salt plain in Chile

Abstract

The nucleus of the Atacama salt plain in Chile is a a brine aquifer that interacts with freshwater aquifers that recharge it from the upper portions of the basin. This interaction originates a saline interface that controls the flow of freshwater entering the salt plain located precisely where a number of different extents  and shapes occur, providing habitats for abundant wildlife. The sustainability of this wildlife depends on the size, depth and chemical properties of the lagoons. This paper reports the study and analysis of the hydrogeological behavior of the saline aquifer and the lagoon zone using a Modflow simulation model. Evaporation from the lagoons and from groundwater is estimated on the basis of field measurements, and the recharge of the freshwater aquifer is estimated by means of a hydrological simulation model using 27 years of precipitation and evaporation data in the basin. Results show that the evaporation losses from groundwater in the vicinity of the lagoons exhibit a strong correlation with seasonal variations of groundwater recharge, and this effect reduces the variations in the net freshwater recharge into the lagoons.