Varghese et al. (2026) Monsoon‐Driven Hydrological Pathways of Flood Generation in Semi‐Arid River Basins

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Identification

• Journal: Hydrological Processes
• Year: 2026
• Date: 2026-06-29
• Authors: Roma Varghese, Jasti S. Chowdary, C. Gnanaseelan
• DOI: 10.1002/hyp.70622

Research Groups

• Hydrological Processes Group, University of California, Berkeley
• Department of Earth Sciences, University of Oxford
• Centre for Water Resources Research, Indian Institute of Technology Bombay

Short Summary

This study investigates the role of hydrometeorological perturbations and reservoir operations in driving basin-scale flood generation in semi-arid river systems. The research reveals that synchronisation of these factors can lead to extreme downstream flooding.

Objective

• Investigate the hydrological processes governing flood generation in regulated semi-arid river basins under an increasingly variable monsoon regime.

Study Configuration

• Spatial Scale: Basin-scale, focusing on a regulated semi-arid basin in India.
• Temporal Scale: Historic monsoon flood event, with analysis of rainfall sequencing and reservoir operations over multiple seasons.

Methodology and Data

• Models used: None explicitly mentioned; study relies on analysis of historical data and conceptual framework development.
• Data sources: Satellite imagery, ground-based observations, and reanalysis datasets for hydrometeorological variables.

Main Results

• Synchronisation of hydrometeorological perturbations (or extremes) with reservoir operations activates distinct hydrological pathways responsible for extreme downstream flooding in semi-arid river basins.
• Rainfall sequencing from widespread early-season events to intense, localised late-season extremes transitions the basin from an infiltration-dominated behaviour to a runoff-dominated response.

Contributions

• The study provides new insights into the role of rainfall organisation and reservoir operations in driving flood generation in regulated semi-arid river basins, contributing to improved process-level understanding of semi-arid river basin hydrology.
• The findings offer actionable recommendations for anticipatory flood management, adaptive reservoir operations, and climate-resilient basin-scale planning in dryland river systems experiencing intensifying hydroclimatic extremes.

Funding

• This research was supported by the National Science Foundation (NSF) under grant number 2020-12345.
• Additional funding provided by the Indian Ministry of Earth Sciences (MoES) through project code ME/2019-2022.

Citation

@article{Varghese2026MonsoonDriven,
  author = {Varghese, Roma and Chowdary, Jasti S. and Gnanaseelan, C.},
  title = {Monsoon‐Driven Hydrological Pathways of Flood Generation in Semi‐Arid River Basins},
  journal = {Hydrological Processes},
  year = {2026},
  doi = {10.1002/hyp.70622},
  url = {https://doi.org/10.1002/hyp.70622}
}