Articles | Volume 30, issue 11
https://doi.org/10.5194/hess-30-3455-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/hess-30-3455-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
05 Jun 2026
Research article |
| 05 Jun 2026
| 05 Jun 2026
Cause-effect discovery in hydrometeorological systems: evaluation of causal discovery methods
Interdisciplinary Centre for Water Research, Indian Institute of Science, Bengaluru, 560012, India
Faculty of Engineering and Information Technology, The University of Melbourne, Melbourne 3010, Victoria, Australia
Murray C. Peel
Faculty of Engineering and Information Technology, The University of Melbourne, Melbourne 3010, Victoria, Australia
Keirnan Fowler
Faculty of Engineering and Information Technology, The University of Melbourne, Melbourne 3010, Victoria, Australia
Dongryeol Ryu
Faculty of Engineering and Information Technology, The University of Melbourne, Melbourne 3010, Victoria, Australia
Bramha Dutt Vishwakarma
Interdisciplinary Centre for Water Research, Indian Institute of Science, Bengaluru, 560012, India
Centre for Earth Sciences, Indian Institute of Science, Bengaluru, 560012, India
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Sandra Pool, Keirnan Fowler, Hansini Gardiya Weligamage, and Murray Peel
Hydrol. Earth Syst. Sci., 30, 2797–2815, https://doi.org/10.5194/hess-30-2797-2026, https://doi.org/10.5194/hess-30-2797-2026, 2026
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Multivariate calibration has become a widely used method to improve model realism. We found that multivariate calibration can lead to less constrained flux maps and more uncertain hydrographs relative to univariate calibration. These symptoms could be caused by non-overlapping behavioural parameter distributions for the individual calibration variables. The results emphasize that the value of non-discharge data in calibration is contingent on the suitability of the model structure.
Nyree Campion, Keirnan Fowler, Margot Turner, and Joel Hall
EGUsphere, https://doi.org/10.5194/egusphere-2026-378, https://doi.org/10.5194/egusphere-2026-378, 2026
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Globally, many river systems have seen less flow for the same rainfall after periods of long drought. This study investigates this behaviour in over 300 catchments across the south-east and south-west of Australia. Through comparison we infer possible underlying causes, expanding on current studies limited to single locations. Over half the catchments studied displayed a drop in flow. We suggest the influence of pre-existing trends in groundwater and highlight the importance of land use history.
Matthew O. Grant, Anna M. Ukkola, Elisabeth Vogel, Sanaa Hobeichi, Andy J. Pitman, Alex Raymond Borowiak, and Keirnan Fowler
Hydrol. Earth Syst. Sci., 29, 5555–5573, https://doi.org/10.5194/hess-29-5555-2025, https://doi.org/10.5194/hess-29-5555-2025, 2025
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Australia is regularly subjected to severe and widespread drought. By using multiple drought indicators, we show that although there have been widespread decreases in droughts since the beginning of the 20th century, many regions have seen an increase in droughts in more recent decades. Despite these changes, our analysis shows that they remain within the range of observed variability and are not unprecedented in the context of past droughts.
Stephan Harrison, Adina Racoviteanu, Sarah Shannon, Darren Jones, Karen Anderson, Neil Glasser, Jasper Knight, Anna Ranger, Arindan Mandal, Bramha Dutt Vishwakarma, Jeffrey S. Kargel, Dan Shugar, Umesh Haritashya, Dongfeng Li, Aristeidis Koutroulis, Klaus Wyser, and Sam Inglis
The Cryosphere, 19, 4113–4124, https://doi.org/10.5194/tc-19-4113-2025, https://doi.org/10.5194/tc-19-4113-2025, 2025
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Climate change is leading to a global recession of mountain glaciers, and numerical modelling suggests that this will result in the rapid disappearance of many glaciers, impacting water supplies. However, an alternative scenario suggests that increased rock fall and debris flows to valley bottoms will cover glaciers with thick rock debris, slowing melting and transforming glaciers into rock–ice mixtures called rock glaciers. This paper explores these scenarios.
Keirnan J. A. Fowler, Ziqi Zhang, and Xue Hou
Earth Syst. Sci. Data, 17, 4079–4095, https://doi.org/10.5194/essd-17-4079-2025, https://doi.org/10.5194/essd-17-4079-2025, 2025
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This paper presents version 2 of the Australian edition of the Catchment Attributes and Meteorology for Large-sample Studies (CAMELS) series of datasets. CAMELS-AUS (Australia) v2 comprises data for an increased number (561) of catchments, each with long-term monitoring, combining hydrometeorological time series with attributes related to geology, soil, topography, land cover, anthropogenic influence and hydroclimatology. It is freely downloadable from https://zenodo.org/doi/10.5281/zenodo.12575680.
Gabrielle Burns, Keirnan Fowler, Murray Peel, and Clare Stephens
EGUsphere, https://doi.org/10.5194/egusphere-2025-3122, https://doi.org/10.5194/egusphere-2025-3122, 2025
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Improving how rainfall-runoff models estimate evapotranspiration is key to better reproducing water partitioning under current conditions, and will increase model realism under future changing conditions. We tested how well different conceptual rainfall-runoff model equations simulate evapotranspiration using Australian catchment and flux tower data. We found one equation consistently worked better than the others. However, even this equation had flaws, pointing to missing vegetation processes.
Maya Raghunath Suryawanshi, K. Satish Kumar, Amin Shakya, Shard Chander, Bhaskar Nikam, Nagesh Kumar Dasika, and Bramha Dutt Vishwakarma
EGUsphere, https://doi.org/10.5194/egusphere-2025-2888, https://doi.org/10.5194/egusphere-2025-2888, 2025
Preprint archived
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Several GRACE downscaling products already available for regional analysis owing to its coarse resolution (~3°). But they lack validation (both original GRACE and downscaled product). Here for the first time, we have validated both, Original GRACE and downscaled product. Along with developed a new product which is outperforming the existing products over most of the parts of India. Thereby, we are offering a valuable tool for regional water resource analysis.
Hansini Gardiya Weligamage, Keirnan Fowler, Margarita Saft, Tim Peterson, Dongryeol Ryu, and Murray Peel
EGUsphere, https://doi.org/10.5194/egusphere-2025-3373, https://doi.org/10.5194/egusphere-2025-3373, 2025
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This study adopts actual evapotranspiration (AET) signatures to diagnose deficiencies in simulation of AET within conceptual rainfall-runoff models. Five models are assessed using flux tower data at 14 Australian sites. Even when AET is included in the calibration, the models struggle to represent aspects of AET dynamics, including interannual variability and timing on seasonal and event scales. The approach shows promise for more insightful critique of model simulations.
Hansini Gardiya Weligamage, Keirnan Fowler, Margarita Saft, Tim Peterson, Dongryeol Ryu, and Murray Peel
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2024-373, https://doi.org/10.5194/hess-2024-373, 2025
Revised manuscript accepted for HESS
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This study is the first to propose actual evapotranspiration (AET) signatures, which can be used to assess multiple aspects of AET dynamics across various temporal scales. As a demonstration, we applied AET signatures to evaluate two remotely sensed (RS) AET products against flux tower AET. The results reveal specific deficiencies in RS AET and provide guidance for selecting appropriate RS AET, including for modelling studies.
Jinghua Xiong, Abhishek, Li Xu, Hrishikesh A. Chandanpurkar, James S. Famiglietti, Chong Zhang, Gionata Ghiggi, Shenglian Guo, Yun Pan, and Bramha Dutt Vishwakarma
Earth Syst. Sci. Data, 15, 4571–4597, https://doi.org/10.5194/essd-15-4571-2023, https://doi.org/10.5194/essd-15-4571-2023, 2023
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To overcome the shortcomings associated with limited spatiotemporal coverage, input data quality, and model simplifications in prevailing evaporation (ET) estimates, we developed an ensemble of 4669 unique terrestrial ET subsets using an independent mass balance approach. Long-term mean annual ET is within 500–600 mm yr−1 with a unimodal seasonal cycle and several piecewise trends during 2002–2021. The uncertainty-constrained results underpin the notion of increasing ET in a warming climate.
Theresa Boas, Heye Reemt Bogena, Dongryeol Ryu, Harry Vereecken, Andrew Western, and Harrie-Jan Hendricks Franssen
Hydrol. Earth Syst. Sci., 27, 3143–3167, https://doi.org/10.5194/hess-27-3143-2023, https://doi.org/10.5194/hess-27-3143-2023, 2023
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In our study, we tested the utility and skill of a state-of-the-art forecasting product for the prediction of regional crop productivity using a land surface model. Our results illustrate the potential value and skill of combining seasonal forecasts with modelling applications to generate variables of interest for stakeholders, such as annual crop yield for specific cash crops and regions. In addition, this study provides useful insights for future technical model evaluations and improvements.
Inès N. Otosaka, Andrew Shepherd, Erik R. Ivins, Nicole-Jeanne Schlegel, Charles Amory, Michiel R. van den Broeke, Martin Horwath, Ian Joughin, Michalea D. King, Gerhard Krinner, Sophie Nowicki, Anthony J. Payne, Eric Rignot, Ted Scambos, Karen M. Simon, Benjamin E. Smith, Louise S. Sørensen, Isabella Velicogna, Pippa L. Whitehouse, Geruo A, Cécile Agosta, Andreas P. Ahlstrøm, Alejandro Blazquez, William Colgan, Marcus E. Engdahl, Xavier Fettweis, Rene Forsberg, Hubert Gallée, Alex Gardner, Lin Gilbert, Noel Gourmelen, Andreas Groh, Brian C. Gunter, Christopher Harig, Veit Helm, Shfaqat Abbas Khan, Christoph Kittel, Hannes Konrad, Peter L. Langen, Benoit S. Lecavalier, Chia-Chun Liang, Bryant D. Loomis, Malcolm McMillan, Daniele Melini, Sebastian H. Mernild, Ruth Mottram, Jeremie Mouginot, Johan Nilsson, Brice Noël, Mark E. Pattle, William R. Peltier, Nadege Pie, Mònica Roca, Ingo Sasgen, Himanshu V. Save, Ki-Weon Seo, Bernd Scheuchl, Ernst J. O. Schrama, Ludwig Schröder, Sebastian B. Simonsen, Thomas Slater, Giorgio Spada, Tyler C. Sutterley, Bramha Dutt Vishwakarma, Jan Melchior van Wessem, David Wiese, Wouter van der Wal, and Bert Wouters
Earth Syst. Sci. Data, 15, 1597–1616, https://doi.org/10.5194/essd-15-1597-2023, https://doi.org/10.5194/essd-15-1597-2023, 2023
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By measuring changes in the volume, gravitational attraction, and ice flow of Greenland and Antarctica from space, we can monitor their mass gain and loss over time. Here, we present a new record of the Earth’s polar ice sheet mass balance produced by aggregating 50 satellite-based estimates of ice sheet mass change. This new assessment shows that the ice sheets have lost (7.5 x 1012) t of ice between 1992 and 2020, contributing 21 mm to sea level rise.
Keirnan Fowler, Murray Peel, Margarita Saft, Tim J. Peterson, Andrew Western, Lawrence Band, Cuan Petheram, Sandra Dharmadi, Kim Seong Tan, Lu Zhang, Patrick Lane, Anthony Kiem, Lucy Marshall, Anne Griebel, Belinda E. Medlyn, Dongryeol Ryu, Giancarlo Bonotto, Conrad Wasko, Anna Ukkola, Clare Stephens, Andrew Frost, Hansini Gardiya Weligamage, Patricia Saco, Hongxing Zheng, Francis Chiew, Edoardo Daly, Glen Walker, R. Willem Vervoort, Justin Hughes, Luca Trotter, Brad Neal, Ian Cartwright, and Rory Nathan
Hydrol. Earth Syst. Sci., 26, 6073–6120, https://doi.org/10.5194/hess-26-6073-2022, https://doi.org/10.5194/hess-26-6073-2022, 2022
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Recently, we have seen multi-year droughts tending to cause shifts in the relationship between rainfall and streamflow. In shifted catchments that have not recovered, an average rainfall year produces less streamflow today than it did pre-drought. We take a multi-disciplinary approach to understand why these shifts occur, focusing on Australia's over-10-year Millennium Drought. We evaluate multiple hypotheses against evidence, with particular focus on the key role of groundwater processes.
Luca Trotter, Wouter J. M. Knoben, Keirnan J. A. Fowler, Margarita Saft, and Murray C. Peel
Geosci. Model Dev., 15, 6359–6369, https://doi.org/10.5194/gmd-15-6359-2022, https://doi.org/10.5194/gmd-15-6359-2022, 2022
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MARRMoT is a piece of software that emulates 47 common models for hydrological simulations. It can be used to run and calibrate these models within a common environment as well as to easily modify them. We restructured and recoded MARRMoT in order to make the models run faster and to simplify their use, while also providing some new features. This new MARRMoT version runs models on average 3.6 times faster while maintaining very strong consistency in their outputs to the previous version.
Fanny Lehmann, Bramha Dutt Vishwakarma, and Jonathan Bamber
Hydrol. Earth Syst. Sci., 26, 35–54, https://doi.org/10.5194/hess-26-35-2022, https://doi.org/10.5194/hess-26-35-2022, 2022
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Many data sources are available to evaluate components of the water cycle (precipitation, evapotranspiration, runoff, and terrestrial water storage). Despite this variety, it remains unclear how different combinations of datasets satisfy the conservation of mass. We conducted the most comprehensive analysis of water budget closure on a global scale to date. Our results can serve as a basis to select appropriate datasets for regional hydrological studies.
Keirnan J. A. Fowler, Suwash Chandra Acharya, Nans Addor, Chihchung Chou, and Murray C. Peel
Earth Syst. Sci. Data, 13, 3847–3867, https://doi.org/10.5194/essd-13-3847-2021, https://doi.org/10.5194/essd-13-3847-2021, 2021
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This paper presents the Australian edition of the Catchment Attributes and Meteorology for Large-sample Studies (CAMELS) series of datasets. CAMELS-AUS comprises data for 222 unregulated catchments with long-term monitoring, combining hydrometeorological time series (streamflow and 18 climatic variables) with 134 attributes related to geology, soil, topography, land cover, anthropogenic influence and hydroclimatology. It is freely downloadable from https://doi.pangaea.de/10.1594/PANGAEA.921850.
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Short summary
Identifying drivers is crucial for process understanding and predictions. In Hydrometeorological systems, many variables are closely related, and common methods often rely on correlation. We describe theoretically distinct methods of discovering cause-effect relations from data. We evaluate them in a large simulated environment. Results show that finding cause-effect relations provides a parsimonious picture and to obtain robust predictions, especially under changing environmental conditions.
Identifying drivers is crucial for process understanding and predictions. In Hydrometeorological...
