MODELING POTENTIAL IMPACTS OF LITHIUM BRINE MINING ON GROUNDWATER DISCHARGE AT SALAR DEL HOMBRE MUERTO, ARGENTINA

Salar del Hombre Muerto, located in the Argentinian portion of the “Lithium Triangle”, hosts the second largest actively producing lithium brine resource in the world. The Salar del Hombre Muerto basin contains one lithium mine at full-scale production with plans for expansion, two mines with active pilot plants, and four claims in early development. These lithium mines operate near sensitive aquatic and wetland ecosystems, which serve as habitat for threatened flamingos as well as cultural resources for the Atacameños del Altiplano Indigenous Community. Previous studies have shown that mostly premodern groundwater discharge is the primary water source to surface water features in these salar systems, sustaining surface water flows during the long periods between intermittent precipitation events. Given the importance of this groundwater-surface water interaction, this study evaluates the potential future impacts of fresh groundwater and brine withdrawals associated with lithium mining on groundwater discharge at Salar del Hombre Muerto. Utilizing the best geologic and hydrogeologic data available within the basin, the study develops hydrogeologic models of the Salar del Hombre Muerto eastern and western subbasins, which inform three-dimensional density-dependent groundwater flow models of the two subbasins. The models simulate a variety of pumping scenarios, including projected fresh groundwater and brine pumping rates for individual lithium mining operations and the combined effects of multiple mining operations. The study then evaluates the effects of these pumping scenarios on groundwater discharge to important surface water features within the basin. This study is the first to evaluate the effects of lithium mining-related groundwater withdrawals on groundwater discharge using density-dependent groundwater flow modeling on a basin scale, and it provides a framework for future evaluations of the hydrologic impacts of lithium brine mining in endorheic basins.