Rivera et al. (2025) Hydrological response to the summer 2024 high-elevation heatwave in Central-Western Argentina

Identification

• Journal: Regional Environmental Change
• Year: 2025
• Date: 2025-10-14
• Authors: Juan Antonio Rivera, C. di Lauro, Leandro Álvarez
• DOI: 10.1007/s10113-025-02472-z

Research Groups

• Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (CCT-Mendoza/CONICET), Mendoza, Argentina
• Instituto Franco-Argentino de Estudios sobre el Clima y sus Impactos (IFAECI)–IRL 3351–CNRS-CONICET-IRD-UBA, Buenos Aires, Argentina

Short Summary

This study characterizes the hydrological response to the summer 2024 high-elevation heatwave in Central-Western Argentina's Mendoza River Basin, revealing an unprecedented snowmelt and glacier melt pulse that significantly increased streamflow, forcing extraordinary dam releases and refilling downstream wetlands for the first time in nearly two decades.

Objective

• Characterize the hydrological impacts of the summer 2024 high-elevation heatwave on the Mendoza River Basin (MRB), quantifying changes in the cryosphere, surface streamflow, and water surface area.

Study Configuration

• Spatial Scale: Mendoza River Basin (MRB) in Central-Western Argentina (approximately 32.5°S; 69°W), covering nearly 20,000 km², with a focus on its upper Andean elevations (exceeding 5000 meters above sea level) and downstream wetlands (Lagunas del Rosario, part of the Ramsar site Lagunas de Guanacache, Desaguadero y del Bebedero). Regional temperature anomalies were evaluated over Central-Western Argentina (31°S to 35°S and 67°W to 70.5°W).
• Temporal Scale: The heatwave occurred from 9 January to 21 February 2024. The analysis period for hydrological response spanned from 1 November 2023 to 31 March 2024. Long-term data records used include streamflow (July 1985–June 2024), snow cover (since 2000), and ERA5 reanalysis (1985–2024).

Methodology and Data

• Models used:
  • Modified Normalized Difference Water Index (MNDWI) for water surface detection from satellite imagery.
  • Linear regression for estimating snow cover reduction rates.
• Data sources:
  • Observation: Daily and hourly streamflow, temperature, and precipitation records from hydrometeorological stations (National System of Hydrological Information, IANIGLA Network of automatic weather stations). Snow Water Equivalent (SWE) records from Toscas station. Potrerillos Dam capacity and water release data (Boletín de Información Hidronivometeorológica). Radiosounding measurements for zero-degree level at Mendoza Airport.
  • Satellite: MODIS Terra & Aqua sensors (500 meters spatial resolution) for snow cover. Sentinel-2 MultiSpectral Instrument (10 meters spatial resolution) for water surface area in wetlands, processed via Google Earth Engine.
  • Reanalysis: ERA5 reanalysis (0.25° × 0.25° spatial resolution) for daily 2 meters air temperature and zero-degree level.

Main Results

• The heatwave (9 January – 21 February 2024) caused mean temperatures in the upper MRB to be more than 3 °C above the long-term mean.
• Maximum temperatures exceeded 10 °C at 4300 meters above sea level, peaking at 13.3 °C on 17 January 2024.
• The zero-degree level increased by almost 450 meters compared to normal conditions, surpassing 5000 meters on 24 days during the heatwave.
• Snow cover decreased at a rate almost 4 times higher than the mean rate observed between 2000 and 2024.
• Streamflow in the Vacas and Mendoza Rivers significantly increased, with the Mendoza River exceeding 190 cubic meters per second (m³/s) for the first time since January 2007, and the Vacas River reaching its highest flow since November 2008.
• Local precipitation during the heatwave was minimal and did not contribute significantly to the streamflow increase, indicating temperature as the primary driver.
• The Potrerillos Dam reached full capacity by late January 2024, necessitating an extraordinary water release that exceeded 150 m³/s on 29–30 January and remained above 100 m³/s for most of February.
• This water release led to an 86% increase in the water surface area of the Lagunas del Rosario wetland (from 151.83 hectares to 282.16 hectares), refilling areas that had been dry since 2006.

Contributions

• Provides the first detailed characterization of the hydrological response to a high-elevation heatwave in the Southern Hemisphere Andes, a region vital for water resources.
• Quantifies the cascading impacts of an extreme heatwave on cryosphere dynamics, riverine streamflow, dam management, and downstream wetland ecosystems within a major Andean river basin.
• Emphasizes the critical need for integrated hydroclimatic monitoring, near-term extreme weather forecasting, hydrological modeling, and long-term planning to enhance water management in climate-vulnerable mountain regions.
• Illustrates the complex interplay between extreme climate events, antecedent environmental conditions (e.g., prior snow accumulation), and anthropogenic water management decisions.

Funding

• National Scientific and Technical Research Council (CONICET) [grant PIBAA 2022-2023 28720210100485CO]

Citation

@article{Rivera2025Hydrological,
  author = {Rivera, Juan Antonio and Lauro, C. di and Álvarez, Leandro},
  title = {Hydrological response to the summer 2024 high-elevation heatwave in Central-Western Argentina},
  journal = {Regional Environmental Change},
  year = {2025},
  doi = {10.1007/s10113-025-02472-z},
  url = {https://doi.org/10.1007/s10113-025-02472-z}
}