Jan Seibert
The 2025 Henry Darcy Medal is awarded to Jan Seibert for pioneering work promoting Open Science with hydrological models, and building bridges between experimentalists and modellers, between physical and conceptual approaches, and to citizen science.
EGU awards Jan Seibert for excellent scientific contributions to water-resources research by advancing hydrological modelling through more robust models. Such models are central for contemporary water-resources engineering and management. Seibert also opens up new data sources, while aiming for consistent improvement and application across disciplines and for results that matter. He emphasises the integration of observational data and models and is a leader in facilitating the discussion between modellers and experimentalists, to reduce the uncertainty in hydrologic models and their predictions. He explored a wide range of methods to deal with uncertainty, including multi-criteria evaluations and concepts such as 'soft' data. He was a first to suggest that expert opinion about process dynamics and recently data from citizen science can be used for model calibration. With an H-Index of 83 and more than 26,000 citations in Google Scholar, his publication record reflects his outstanding rank among hydrologists globally.
Jan Seibert is a key person in improving and distributing the HBV model, and he was ahead of his time when openly sharing his updated HBV-light version long before "open science" became a concept. Seibert is also highly influential in deriving novel metrics and landscape characteristics that are now used to solve water-resources management questions. He has also bridged quantitative and qualitative hydrology, improving the predictability of water quality, but also using stable isotopes of water to explore flow paths, especially with a focus on Nordic and Boreal landscapes.
Seibert has bridged groundwater and surface water hydrology, stressing the urgent need to understand and model processes from the cryosphere to surface and subsurface water flow. He also connected to the climate-change community, by applying bias correction methods of forcing data to reduce uncertainties in hydrological-impact modelling.
Seibert's special ability to bridge also becomes evident through his work with many and very successful students. He is not only an excellent and influential teacher and mentor, he chairs many teaching committees and has continuously developed new tools to improve education in hydrology. In addition, Seibert teaches the public; his recent interests in linking researchers with society resulted in an app-assisted monitoring of rivers. As he has demonstrated, this citizen-science based data collection and the other approaches to tackle inconsistent or short data sources helps models for prediction.
Truly outstanding is also Seibert's service to the hydrological science community, where his tasks in Swiss and international committees are numerous. In 2007, Seibert received an EGU Service award for his commitments as chair of EGU's Catchment Hydrology sub-division and initiator of the now titled Outstanding Student and PhD candidate Presentation (OSPP) awards. Moreover, his immense dedication as reviewer and various roles as Editor for several high-ranking journals, resulted in an Outstanding Editor Award 2019 for HESS. His instrumental role in establishing WIRES Water emphasizes his passion to make hydrology accessible within and across disciplines.
The long list of nearly gender-balanced students and collaborators on many different topics demonstrates his exceptionally wide interest, his profound impact into the community, and his great collegiality and mentorship, which makes him well-worthy of the Henry Darcy medal of 2025.