Sharma et al. (2026) Impact of Reservoirs on Streamflow Extremes in India

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

Identification

• Journal: Geophysical Research Letters
• Year: 2026
• Date: 2026-11-02
• Authors: P. Sharma, Naoki Mizukami, Manabendra Saharia
• DOI: 10.1029/2026gl125455

Research Groups

Not specified in abstract.

Short Summary

This study quantifies the impact of 223 reservoirs on India's streamflow extremes using a national hydrologic modeling system, revealing significant attenuation of monsoon high flows and augmentation of pre-monsoon low flows, but also highlighting a high vulnerability due to rapid reservoir saturation.

Objective

• To quantify how reservoirs have altered the natural flow regime and influenced streamflow extremes across India.

Study Configuration

• Spatial Scale: National scale, covering India.
• Temporal Scale: Not specified in abstract.

Methodology and Data

• Models used: Noah-MP land surface model, MizuRoute hydrodynamic model.
• Data sources: Integration of 223 reservoirs into a national hydrologic modeling system; specific data types (e.g., observed streamflow, precipitation, reservoir characteristics) not detailed in abstract but implied as model inputs.

Main Results

• Including reservoirs improved national streamflow Nash-Sutcliffe Efficiency (NSE) by 43%.
• Reservoirs provide a median attenuation of 46.1% for monsoon high flow peaks.
• Reservoirs lead to a 235% augmentation of pre-monsoon low flows.
• Large reservoirs (≥ 1000 MCM or 10^9 m^3) primarily control the magnitude of flow extremes.
• Smaller reservoirs (< 1000 MCM or 10^9 m^3) are responsible for a 1-3 day onset lag in flow extremes.
• 74% of reservoirs reach near full capacity the day immediately after a high flow peak, indicating systematic saturation and high vulnerability to sequential high inflows.

Contributions

• Provides a national-scale quantification of reservoir impacts on streamflow extremes in India, an area previously poorly quantified.
• Highlights the differential roles of large versus small reservoirs in controlling flow magnitude and timing.
• Identifies a critical vulnerability in the current reservoir network operation due to rapid saturation, advocating for a shift towards forecast-informed operations to mitigate risk.

Funding

Not specified in abstract.

Citation

@article{Sharma2026Impact,
  author = {Sharma, P. and Mizukami, Naoki and Saharia, Manabendra},
  title = {Impact of Reservoirs on Streamflow Extremes in India},
  journal = {Geophysical Research Letters},
  year = {2026},
  doi = {10.1029/2026gl125455},
  url = {https://doi.org/10.1029/2026gl125455}
}