Hydrological signatures in wetlands in the lithium-rich salar basins of the Andes, South America

Abstract Despite the importance of surface water resilience to local ecosystems in arid and endorheic basins, the current understanding of surface water sensitivity to climate-driven hydrologic perturbations in such environments remains limited to basin-scale water budget analysis and often ignores the complex relationships between these surface waters and sources of recharge. We investigate the driving factors of surface water variability and drought vulnerability for the Altiplano-Puna region of the Andes in South America with satellite imagery via the Landsat-based JRC Surface Water Product and the Sentinel mission. We further identify areas of surface water-adjacent groundwater discharge through the normalized difference vegetation index and compare fluctuations in vegetated area to variability in surface water inundation. Regression analysis between surface water inundation and monthly average temperature through FLDAS and precipitation through Terraclimate also provides an opportunity to assess climate-driven sensitivity. Surface waters throughout the Altiplano-Puna show resilience to a prolonged region-wide drought which occurred between 2003 and 2012. However, high-elevation (>4,000 masl) surface water bodies exhibit statistically significant declines in surface water inundation, but these same surface water bodies show the highest post-drought rebounds. Increased sensitivity in vegetated area fluctuation adjacent to areas of higher surface water drought sensitivity indicates that surface water bodies are reliant on groundwater discharge. An exploration of basin attributes further suggests that higher-elevation basins experience higher variability in groundwater and surface water fluctuations, suggesting not only that both systems are closely coupled but also that increasing precipitation at higher elevations introduces more variability in the hydrologic pathways to local surface waters. We present the first regional study of arid, endorheic basins to define mechanisms of surface water resilience and determine the importance of groundwater discharge dynamics in such environments. This study further provides a framework for assessing surface water resilience for both the Altiplano-Puna and other similarly arid regions (e.g. the Tibetan Plateau, the Great basin, etc.).