Preprints
https://doi.org/10.5194/egusphere-2025-3586
https://doi.org/10.5194/egusphere-2025-3586
30 Jul 2025
 | 30 Jul 2025

Multi-site learning for hydrological uncertainty prediction: the case of quantile random forests

Taha-Abderrahman El Ouahabi, François Bourgin, Charles Perrin, and Vazken Andréassian

Abstract. To improve hydrological uncertainty estimation, recent studies have explored machine learning (ML)-based post-processing approaches that enable both enhanced predictive performance and hydrologically informed probabilistic streamflow predictions. Among these, random forests (RF) and their probabilistic extension, quantile random forests (QRF), are increasingly used for their balance between interpretability and performance. However, the application of QRF in regional post-processing settings remains unexplored. In this study, we develop a hydrologically informed QRF post-processor trained in a multi-site setting and compare its performance against a locally (at-site) trained QRF using probabilistic evaluation metrics. The QRF framework leverages simulations and state variables from the GR6J hydrological model, along with readily available catchment descriptors, to predict daily streamflow uncertainty. Our results show that the regional QRF approach is beneficial for hydrological uncertainty estimation, particularly in catchments where local information is insufficient. The findings highlight that multi-site learning enables effective information transfer across hydrologically similar catchments and is especially advantageous for high-flow events. However, the selection of appropriate catchment descriptors is critical to achieving these benefits.

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Journal article(s) based on this preprint

12 Jun 2026
Multi-site learning for hydrological uncertainty prediction: the case of quantile random forests
Taha-Abderrahman El Ouahabi, François Bourgin, Charles Perrin, and Vazken Andréassian
Hydrol. Earth Syst. Sci., 30, 3549–3574, https://doi.org/10.5194/hess-30-3549-2026,https://doi.org/10.5194/hess-30-3549-2026, 2026
Short summary
Taha-Abderrahman El Ouahabi, François Bourgin, Charles Perrin, and Vazken Andréassian

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • AC1: 'Minor typo detected', Taha-Abderrahman El-Ouahabi, 18 Sep 2025
  • RC1: 'Comment on egusphere-2025-3586', Anonymous Referee #1, 25 Sep 2025
    • AC2: 'Reply on RC1', Taha-Abderrahman El-Ouahabi, 18 Dec 2025
  • RC2: 'Comment on egusphere-2025-3586', Derek Karssenberg, 17 Oct 2025
    • AC3: 'Reply on RC2', Taha-Abderrahman El-Ouahabi, 18 Dec 2025
    • AC4: 'Reply on RC2', Taha-Abderrahman El-Ouahabi, 18 Dec 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • AC1: 'Minor typo detected', Taha-Abderrahman El-Ouahabi, 18 Sep 2025
  • RC1: 'Comment on egusphere-2025-3586', Anonymous Referee #1, 25 Sep 2025
    • AC2: 'Reply on RC1', Taha-Abderrahman El-Ouahabi, 18 Dec 2025
  • RC2: 'Comment on egusphere-2025-3586', Derek Karssenberg, 17 Oct 2025
    • AC3: 'Reply on RC2', Taha-Abderrahman El-Ouahabi, 18 Dec 2025
    • AC4: 'Reply on RC2', Taha-Abderrahman El-Ouahabi, 18 Dec 2025

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
ED: Publish subject to revisions (further review by editor and referees) (19 Dec 2025) by Albrecht Weerts
AR by Taha-Abderrahman El Ouahabi on behalf of the Authors (01 Mar 2026)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (16 Mar 2026) by Albrecht Weerts
RR by Derek Karssenberg (16 Apr 2026)
ED: Publish subject to minor revisions (review by editor) (11 May 2026) by Albrecht Weerts
AR by Taha-Abderrahman El Ouahabi on behalf of the Authors (28 May 2026)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (28 May 2026) by Albrecht Weerts
AR by Taha-Abderrahman El Ouahabi on behalf of the Authors (29 May 2026)

Journal article(s) based on this preprint

12 Jun 2026
Multi-site learning for hydrological uncertainty prediction: the case of quantile random forests
Taha-Abderrahman El Ouahabi, François Bourgin, Charles Perrin, and Vazken Andréassian
Hydrol. Earth Syst. Sci., 30, 3549–3574, https://doi.org/10.5194/hess-30-3549-2026,https://doi.org/10.5194/hess-30-3549-2026, 2026
Short summary
Taha-Abderrahman El Ouahabi, François Bourgin, Charles Perrin, and Vazken Andréassian
Taha-Abderrahman El Ouahabi, François Bourgin, Charles Perrin, and Vazken Andréassian

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Latest update: 13 Jun 2026
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Short summary
To improve hydrological uncertainty estimation, recent studies have explored machine learning (ML)-based post-processing approaches. Among these, quantile random forests (QRF) are increasingly used for their balance between interpretability and performance. We develop a hydrologically informed QRF trained in a multi-site setting. Our results show that the regional QRF approach is beneficial, particularly in catchments where local information is insufficient.
Share