Identification of the recharge zone using stable isotopes in the Salar de Atacama, Chile

In the peripheral aquifer of the Salar de Atacama, recharge is a key term of the water balance. This recharge is produced under arid conditions in the sub-basins surrounding the Salar and is dominated by medium salinity water due the intense evapo-concentration conditions. To solve the uncertainty in closing the water balance in the Salar de Atacama basin, this study aims to characterize the isotopic composition of precipitation, groundwater and surface water and to identify the recharge area. The results show that winter precipitation is more depleted in heavy isotopes, δ²H and δ¹⁸O, than summer precipitation. Surface water is evaporated and it has the same isotopic footprint as groundwater in each sub-basin, indicating that surface water runoff is a main recharge component. The meteoric source of surface and underground water in the basins of the Altiplano-Puna Plateau is isotopically lighter than the other waters found in the Salar de Atacama basin, although there is no significant transfer of isotopically lighter water to the peripheral aquifer of the Salar de Atacama from areas significantly outside the hydrographic basin.