The Salar de Atacama Basin, in northern Chile, is located in one of the driest regions on Earth; its hydrological system depends heavily on high-altitude precipitation, making it highly sensitive to climate variability. However, existing studies have relied on short records or lack spatially explicit drought assessments, limiting the understanding of how precipitation decline and rising temperatures interact across different sectors of the basin. Spatiotemporal dynamics of drought in the basin were analyzed over 1990–2024 using the standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI). Mean monthly temperature and precipitation data from 20 meteorological stations were combined with ERA5-Land satellite products and corrected using random forest and kriging techniques to generate bias-adjusted monthly climate rasters. The indices were computed at the pixel level and analyzed using both long-term trends and 5-year interval classifications. The results showed a progressive intensification of aridity, with SPI undergoing a statistically significant increase in the moderate drought class and a reduction in the normal drought class, indicating declining precipitation levels. Since 2010, droughts in the region have predominantly exhibited a hydroclimatic state, peaking between 2020 and 2024 when up to 80% of the basin experienced drought. The SPEI revealed a broader spatial extent of drought due to increasing temperatures and evapotranspiration, although long-term trends were less pronounced. Mild and moderate droughts were the most frequent and spatially extensive, particularly in the headwater and salt flat surface zones, where water availability was critical for aquifer recharge and local supply. Graphical Abstract This graphical abstract presents a clear and logical workflow that integrates data from multiple sources, including data from in situ meteorological stations, satellite-based information, ERA5-Land reanalysis data, and topographic information derived from a digital elevation model. These datasets were combined through a calibration process using a random forest model, spatial downscaling with altitude, and bias correction and geostatistical interpolation, resulting in high-resolution raster datasets for precipitation and temperature. The analytical framework illustrated in the graphical abstract generates long-term monthly datasets (1990–2024) that are subsequently used to calculate the standardized precipitation index (SPI) and the standardized precipitation-evapotranspiration index (SPEI). The visual sequence emphasizes how these indices enable the characterization of drought intensity, frequency, and spatial maps and temporal trends that reveal a progressive intensification of aridity, with an expansion of moderate-to-extreme drought conditions, particularly since 2010. The Salar Atacama basin is experiencing increasing drought severity driven by declining precipitation and rising temperatures, with significant implications for water resources, ecosystems, and communities.

Basin Under Stress: 35 Years of Expanding Drought in the Salar de Atacama

期刊论文
发表日期：

2026年5月12日

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Florencia Tillería,
Jorge Soto,
Manuel Paneque

摘要

The Salar de Atacama Basin, in northern Chile, is located in one of the driest regions on Earth; its hydrological system depends heavily on high-altitude precipitation, making it highly sensitive to climate variability. However, existing studies have relied on short records or lack spatially explicit drought assessments, limiting the understanding of how precipitation decline and rising temperatures interact across different sectors of the basin. Spatiotemporal dynamics of drought in the basin were analyzed over 1990–2024 using the standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI). Mean monthly temperature and precipitation data from 20 meteorological stations were combined with ERA5-Land satellite products and corrected using random forest and kriging techniques to generate bias-adjusted monthly climate rasters. The indices were computed at the pixel level and analyzed using both long-term trends and 5-year interval classifications. The results showed a progressive intensification of aridity, with SPI undergoing a statistically significant increase in the moderate drought class and a reduction in the normal drought class, indicating declining precipitation levels. Since 2010, droughts in the region have predominantly exhibited a hydroclimatic state, peaking between 2020 and 2024 when up to 80% of the basin experienced drought. The SPEI revealed a broader spatial extent of drought due to increasing temperatures and evapotranspiration, although long-term trends were less pronounced. Mild and moderate droughts were the most frequent and spatially extensive, particularly in the headwater and salt flat surface zones, where water availability was critical for aquifer recharge and local supply.

Graphical Abstract

This graphical abstract presents a clear and logical workflow that integrates data from multiple sources, including data from in situ meteorological stations, satellite-based information, ERA5-Land reanalysis data, and topographic information derived from a digital elevation model. These datasets were combined through a calibration process using a random forest model, spatial downscaling with altitude, and bias correction and geostatistical interpolation, resulting in high-resolution raster datasets for precipitation and temperature. The analytical framework illustrated in the graphical abstract generates long-term monthly datasets (1990–2024) that are subsequently used to calculate the standardized precipitation index (SPI) and the standardized precipitation-evapotranspiration index (SPEI). The visual sequence emphasizes how these indices enable the characterization of drought intensity, frequency, and spatial maps and temporal trends that reveal a progressive intensification of aridity, with an expansion of moderate-to-extreme drought conditions, particularly since 2010. The Salar Atacama basin is experiencing increasing drought severity driven by declining precipitation and rising temperatures, with significant implications for water resources, ecosystems, and communities.