Shah et al. (2025) Global patterns of reservoir fullness and fluctuations during droughts

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Environmental Research Letters
• Year: 2025
• Date: 2025-11-26
• Authors: Deep Shah, Huilin Gao
• DOI: 10.1088/1748-9326/ae2493

Research Groups

Not explicitly stated in the abstract.

Short Summary

This study assesses the storage conditions and fluctuations of 6634 global reservoirs during major river basin-scale droughts from 1999 to 2018, revealing significant regional, functional, and socio-economic disparities in reservoir resilience and a strong link to large-scale climate variability.

Objective

• To assess the storage conditions (fullness and fluctuations) of global reservoirs during major river basin-scale droughts and understand how these conditions relate to reservoir function, size, location, climate, and socio-economic context.

Study Configuration

• Spatial Scale: Global, covering 6634 reservoirs across major river basins, with specific analysis for continents (Asia, Africa) and climate zones.
• Temporal Scale: 20 years (1999–2018).

Methodology and Data

• Models used:
  • Standardized Precipitation Evapotranspiration Index (SPEI) at a 6-month timescale for identifying river basin-scale drought spells.
  • Normalized Storage (NS; storage-to-capacity ratio) for assessing reservoir fullness and fluctuations.
• Data sources:
  • Storage conditions of 6634 global reservoirs (specific source not detailed in abstract).
  • Precipitation and evapotranspiration data used to compute SPEI (specific source not detailed in abstract).
  • Oceanic Niño Index (ONI) for large-scale climate variability.

Main Results

• Reservoirs in Asia exhibited the lowest Normalized Storage (NS) levels during droughts.
• Reservoirs in Africa and Asia showed the largest NS fluctuations, with median fluctuations of 34% and 37%, respectively.
• Large capacity reservoirs demonstrated greater resilience with less fluctuation, while smaller reservoirs fluctuated more.
• Irrigation reservoirs consistently had the lowest NS levels (49%) and the greatest NS fluctuations (33%).
• Reservoirs in dry climates remained the least filled, with irrigation reservoirs showing the largest fluctuations across all climate zones.
• Reservoirs in economically stronger countries maintained higher storage levels (61% vs. 46%) and lower fluctuations (23% vs. 33%) during droughts.
• Approximately 40% of all reservoirs showed a significant (p < 0.05) correlation between NS and the Oceanic Niño Index (ONI).

Contributions

• Provides valuable observational insights into global reservoir storage dynamics during droughts, highlighting regional, functional, size-dependent, climatic, and socio-economic disparities.
• Establishes a quantitative link between large-scale climate variability (ONI) and reservoir storage dynamics for a significant portion of global reservoirs.
• Offers a foundation for guiding targeted management strategies and contributing to sustainable, long-term water governance.

Funding

Not explicitly stated in the abstract.

Citation

@article{Shah2025Global,
  author = {Shah, Deep and Gao, Huilin},
  title = {Global patterns of reservoir fullness and fluctuations during droughts},
  journal = {Environmental Research Letters},
  year = {2025},
  doi = {10.1088/1748-9326/ae2493},
  url = {https://doi.org/10.1088/1748-9326/ae2493}
}