López et al. (2026) Tracking hydrological drought propagation in river networks: an event-based framework

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-10-05
• Authors: Alex Crespillo López, S.M.Vicente Serrano, L. Gimeno
• DOI: 10.1016/j.jhydrol.2026.136544

Research Groups

• Pyrenean Institute of Ecology, IPE-CSIC
• Laboratory of Climatology and Climate Services (LCSC)
• Environmental Physics Laboratory (EPhysLab)
• CIM-UVigo
• CSIC-Zaragoza University
• Galicia Supercomputing Center (CESGA)

Short Summary

This study introduces a novel event-based framework to analyse the spatiotemporal propagation of hydrological droughts along river networks. The method identifies drought events independently at each gauging station using the Standardised Streamflow Index (SSI) and reconstructs propagation chains by linking temporally consistent upstream and downstream events based on network connectivity.

Objective

• Develop an event-based methodology to identify and track hydrological drought propagation along river networks.
• Characterise and quantify the spatiotemporal characteristics of drought propagation using network-based metrics.
• Apply the framework to a dense gauging network in order to identify and interpret dominant propagation patterns at the basin and subcatchment scale.

Study Configuration

• Spatial Scale: River network, Ebro River Basin (Spain)
• Temporal Scale: Daily streamflow records from 1961–2020

Methodology and Data

• Models used: Standardised Streamflow Index (SSI), event-based algorithm
• Data sources: Daily discharge observations from the Spanish hydrological monitoring network managed by the Centro de Estudios y Experimentació de Obras Públicas (CEDEX)

Main Results

• The framework reconstructs directional, upstream-to-downstream propagation chains at the level of individual drought events across a dense gauging network.
• Drought propagation chains are characterised using metrics describing their spatial extent, timing, and severity.
• The study illustrates the substantial variability that may characterise the propagation dynamics, with events ranging from localised sub-basin responses to basin-wide droughts involving a large proportion of the upstream network.

Contributions

• This study provides a process-orientated perspective on hydrological droughts, generating a propagation-chain catalogue that offers a new data foundation for characterising basin-specific drought dispersal regimes.
• The framework characterises upstream drought signals and cumulative downstream deficits, providing a reproducible basis for future research and for the development of early-warning applications.

Funding

• This work was supported by the Spanish Ministry of Science and Innovation (grant number XXXX) and the European Union's Horizon 2020 research and innovation programme (grant agreement number YYYY).

Citation

@article{López2026Tracking,
  author = {López, Alex Crespillo and Serrano, S.M.Vicente and Gimeno, L.},
  title = {Tracking hydrological drought propagation in river networks: an event-based framework},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.136544},
  url = {https://doi.org/10.1016/j.jhydrol.2026.136544}
}