Hydrological Sciences
Matthias Sprenger

Matthias Sprenger

Matthias Sprenger is a postdoctoral fellow at North Carolina State University (United States) and the Institute of Environmental Assessment and Water Research (IDAE-CSIC) in Barcelona, Spain. He uses stable isotope of water to track water through the critical zone, the Earth’s thin layer spanning from the canopy to the groundwater. Matthias works currently on a DFG-funded project on “Water age dynamics in a Mediterranean catchment and their ecohydrological implications in a changing environment”. He tweets as @MatthiaSprenger

Hydrologists Join Youth-Led #GlobalClimateStrike

Hydrologists Join Youth-Led #GlobalClimateStrike

In a powerful sign of solidarity, adults from across an estimated 185 countries took to the streets to join last Friday’s youth-led Global Climate Strike, the largest climate protest in history. Among those in attendance were hydrologists from around the world, who stood shoulder to shoulder with young people to support their calls for immediate climate action.

As a hydrologist who participated in the Global Climate Strike, I was interested in exploring my colleagues’ motivations for attending in hopes of learning more about how I — along with the broader scientific community — can continue to support youth-led efforts for climate justice. So I reached out to hydrologists from across the globe and at different career stages. This is what they had to say. All statements presented reflect the views of the individual contributors.

James Bennett is a Senior Research Scientist at CSIRO, Australia.

James Bennett (Melbourne, Australia): “I support the climate strike for my kids. I mean this both in the immediate sense – both my children wanted to go to the strike, and they are too young to go unsupervised – and also in the broader sense, in that their generation and beyond will wear the worst consequences of inaction. Children are clear-eyed about it: they are outraged by the damage we are doing to our natural world and the risks we are taking with the health and happiness of millions of people. And of course they are right.
I also think scientists can provide important support to activists, even if our research isn’t directly addressing climate science (my research doesn’t). We know how hard it is get our work through peer review. And if you work in the earth sciences, chances are you personally know colleagues researching climate, and you know that they are highly trained and dedicated. So our confidence in climate science doesn’t draw only from theory or reading papers, but also from knowing first-hand how rigorous it is. Nothing shows our confidence in the science better than standing shoulder to shoulder with activists. I think it’s our moral obligation to support them.”

Upper right: (Credit: @fff_ankara), Bottom: (Credit: @fff_ankara), Upper left: Nilay, a hydrologist from Middle East Technical University, Turkey, with Buse, a 16-yrs old climate activist.

Nilay Dogulu (Ankara, Turkey): “Planet Earth is wonderful with its ALL habitants regardless of any differences. It is time to raise the consciousness of humans to bring back equity for all, starting with Nature. Earth needs to recover from a sickness (#ClimateCrisis), and each and every cell of Earth (#You, yes you!) must act together to its highest will and strength possible to help this massive cleaning & healing.
Buse is only 16 years old, half of my age (Oddly enough I look very young next to her). She has a very strong sense of courage and perseverance for uniting against climate crisis.
As a women in science, I value the power of youth striking against climate crisis. What’s happening today all around the world is just the beginning. We are moving towards a golden age and it is being led by youth. Now is the time to blend in!”

Dr. Luis Samaniego, Deputy Head of Department of Computational Hydrosystems Helmholtz-Zentrum for Environmental Research – UFZ with colleagues on the Climate Strike in Leipzig, Germany.

Luis Samaniego (Leipzig, Germany): “Available hydro-metereological observations show that the Earth climate is changing fast and may reach a point-of-no-return in the coming decades. Recent research shows that “extreme temperature records will be set in approximately 58% of the world every year” (Power & Delage, 2019). These dramatic changes will have negative consequences for the ecosystems and will be decisive for the fate of humanity in this planet, the only one we have. In Europe, for example, state-of-the-art climate and hydrological projections show that the mean area under extrem heatwaves will increase from 5% under a +1.5 C world (w.r.t. preindustrial times) to 18% under a +3 C world. Similarly, drought area will increase by 40% (± 24%) and will affect 42% (± 22%) more people (Samaniego et. al., 2018). Dry periods will become hotter! According to the IPCC, the chance to stay below the +1.5 C world is around 50%. This means that we don’t have much time left to take actions…For these reasons, I urge every concerned citizen to do as much as possible to reduce of their CO2 footprint now. Similarly, I demand our elected officials to take immediately actions leading to come to an end the age of fossil fuels. As as scientist, I also urge my colleagues to raise their voices and help to illustrate those fellow citizens that are not aware of these hard scientific facts or that have been misled by ignorant politicians.”

Dr. Katerina Michaelides, Senior Lecturer at the School of Geographical Sciences, University of Bristol, UK.

Katerina Michaelides (Bristol, UK): “I think we owe it to today’s youth to support them in their fight for reducing greenhouse gas emissions and slowing down the rate of climate change. I work on the impacts of climate change on the water security in East Africa. From our research, it is clear to me that this region is suffering more frequent and more intense droughts as a result of climate change over the last three decades. The implications for millions of people are immense – loss of livelihoods, mass human migration, loss of biodiversity, water scarcity and food insecurity, disease, conflict… I don’t want climate change concerns and impacts to dominate the future of my daughter’s generation.”

Prof. Werner Aeschbach from the Inst. of Environmental Physics, University of Heidelberg, Germany.

Werner Aeschbach (Heidelberg, Germany): “I support the climate strike movement because the young protesters explicitly refer to climate science. As environmental scientist aware of the severity of the climate crisis I feel obliged to confirm that the protesters’ concerns are justified, thus I signed the corresponding statement issued by the “Scientists for Future” (Hagedorn et al., 2019, GAIA 28: 79-87). The climate strikers need our backing and we scientists need their societal impact if we want that our warnings about climate change, biodiversity loss, or water crises are heard by the public and by political leaders.”

Kelly Hondula (Annapolis, USA): “I support the climate strike because I’m inspired by the organizers and want to amplify their voices, passion, and vision. Research in journal articles can only go so far towards informing public consciousness and policy decisions that affect our planet. Aside from calling for action from governments and corporations on climate policy, participating motivates an urgency for me to conduct rigorous science that is relevant for figuring out how to create a just and livable future — especially for the generations that are still counting down the days until they can vote.”

Kelly Hondula, a PhD Student in Water Resources at the National Socio-Environmental Synthesis Center, University of Maryland, USA.


Ryan Emanuel (Raleigh, USA): “Young people need to know they are acting not only with the support of scientific consensus, but also with the support of actual scientists. As their teachers, parents, elders, and mentors, we should stand alongside youth who speak out for the future they want instead of the future they see being prepared for them. With that in mind, I fully support the youth climate strike and other actions that bring attention to the climate crisis.”

Prof. Ryan Emanuel from the Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, USA.

Guillaume Thirel (Paris, France): “As a scientist working on climate change, and a human being sensitive to environmental issues, I felt that joining the climate strike was compulsory. We have to help and support this youth that seems to be our best option to evolve towards a sustainable future.”

Protesters on the climate strike in Paris, that Guillaume Thirel, a researcher at Irstea, France, attended.

Hannes Müller-Thomy, postdoc at the Institute of Hydraulic Engineering and Water Resources Management, TU Vienna, Austria.

Hannes Müller-Thomy (Vienna, Austria): “I strongly support these kind of demonstrations to raise the awareness for the biggest challenge in humankind. Only if we all face it together, we will have a chance to deal with it. The demonstrations are a perfect starting point to show this union spirit.”

Dr. Gökçen Uysal, Asst. Prof. at the Department of Civil Engineering, Eskisehir Technical University, Turkey.

Gökçen Uysal (Eskisehir, Turkey): “We are uncontrollably changing the climate and disturbing the natural life in this wonderful Earth. This is happening right now and in every moment, it is real! One of the biggest exam of humankind of this era is that whether we will be still ignoring the damage we have done or not. More terrifying is, most of the people are not yet aware of this destruction or they are pretending as if it does not exist. We do not have too much time to take an action. This global climate strike brings awareness for us, for all, for every life in the world, and I believe we as scientists should be shouldering responsibility more than anyone else.”

Prof. Michael Stewardson, Department of Infrastructure Engineering | Melbourne School of Engineering, Discipline leader Environmental Hydrology and Water Resources

Michael Stewardson (Melbourn, Australia): “I’m supporting the Climate Strike because I am worried about the future. It is apparent that good science and evidence-based communication is not enough to drive the necessary transformations.”

Sina Khatami (Melbourn, Australia) (no photo): “I support climate strike because climate change is an existential threat to our species, one that has never arisen in human history. If we want organized human life to survive in any decent form, we need to pressure politicians and other decision makers to take meaningful actions NOW.”




Unfortunately, I have not yet received contributions from South America and Africa.

“Everything is interaction and reciprocal”

“Everything is interaction and reciprocal”

The first time I came across Alexander von Humboldt I was a freshman at the University of Bayreuth. We were proudly told that we were studying environmental science in a region where Humboldt used to work in, prior to his adventures in the Americas. Within EGU, von Humboldt is well known, in connection with the Union medal for “scientists who have performed research in developing regions for the benefit of people and society”, which is awarded in his memory. To celebrate Humboldt’s 250th birthday this year, I share how reading about him has encouraged my research.

Global networks –possible and critical

Example of an early map of the magnetic field using isodynamics lines. https://commons.wikimedia.org/wiki/File:FMIB_43939_Isodynamic_Lines.jpeg

Humboldt was extremely well connected with other scientists. He used his network to push for measurement networks of the Earth’s magnetic field and climate. While scientists in the 21st century are more connected than ever, we still benefit enormously from global measurement initiatives such as the Global Network of Isotopes in Precipitation (GNIP) or the FluxNET network to measure ecosystem carbon, water, and energy fluxes. Similar to von Humboldt’s initiatives, which allowed to map the spatial variability of both the magnetism using isodynamic lines (Fig. 1) and air temperature using isotherms, GNIP enables deriving the geographical patterns in the isotopic compositions of precipitation and FluxNET exposes global variability of evapotranspiration. I believe that such global networks provide invaluable insights on linkages between hydrology, climatology, and biogeochemistry and that these approaches shape our understanding of the most pressing water issues.

Von Humboldt got frustrated when his explorations were sometimes stopped or delayed by political developments (e.g. Napoleonic wars, British colonialism). Similarly, I get upset by political decisions that are counterproductive for scientific networks, such as changing Visa requirements and Brexit. Nevertheless, I have the impression that global scientific networks are doing well and that – very much in the light of von Humboldt’s support of junior researchers – early career scientists often get great support from established researchers.

All is interaction? – connecting human and ecological dimensions

How would Alexander von Humboldt do research today? Maybe he would do various measurements using the latest technical developments from remote sensing, field observations and tracer data? (Original photo from: https://en.wikipedia.org/wiki/Alexander_von_Humboldt#/media/File:Alexandre_humboldt.jpg)

Humboldt is seen as a “nomad of science, a traveler who connected the most diverse regions and cultures as well as the most different sciences”. During von Humboldt’s time, his “conceptual unification among the sciences of the Earth” was relatively exceptional in an era of disciplinary specialization. He realized on his exploration in the Americas that “Alles ist Wechselwirkung” (he wrote in 1803 in his otherwise French diary; Engl. “All is interaction and reciprocal”), which seems for most of us nowadays probably as a truism. But, do we account for it in our research? I think that emerging ideas in ecohydrology and concepts such as catchment co-evolution and the critical zone are critical for transdisciplinary research, and some even say that Humboldt “foreshadowed” critical zone science.

Recent commentaries in hydrology outline how Socio-hydrology is “a new science of people and water” and the International Association of Hydrological Sciences dedicated the current scientific decade (2013–2022) to research activities on change in hydrology and society to foster this field of science. These initiatives have a lot in common with Humboldt’s views. Linkages between past and present are very explicit in his Personal Narrative, written about 200 years ago, in which he reflects upon the conflict between economic progress and ecohydrological degradation: “By felling the trees, that cover the tops and the sides of mountains, men in every climate prepare at once two calamities for future generations; the want of fuel and a scarcity of water.”

Humboldt acknowledged problems that transcend generations and his awareness of environmental justice were new to his time. Today, we are concerned about “hydrological justice” (just 105 results on Google search), when we think for example of the inequality with regard to access to clean water, pollution of rivers, and hydrometeorological impacts of climate change. Hydrologists help describing these problems and providing suggestions to solve them. In this context, reading about von Humboldt inspires me to do Humboldtian Science which “could be described as the construction of a network between the different sciences and the different scientists”.

Welcome to the HS division blog

Welcome to the HS division blog

The Hydrological Sciences (HS) Division of the EGU is launching its new blog!

Finally, the HS Division is entering the EGU Blogsphere! With this blog, we aim at giving the HS community a platform to communicate new ideas and old thoughts, a bit of history and future perspectives, as well as a glimpse at experimental and modelling studies. In other words, it is a platform to share news, research, and opinions on hydrological processes and applications.

We hope the blog will cover all topics addressed within the hydrology division (and beyond!). The hydrology division is very diverse. This can be seen at the EGU General Assembly in Vienna where we organize more than one hundred scientific sessions under the umbrella of 10 sub-divisions. Topics can range from precipitation extremes to million-year-old groundwater, can cover scales of millimeters to the entire planet, and can occur in pristine landscapes and mega cities. Many topics nowadays cross disciplines, thus we also welcome contributions highlighting interactions between hydrology and other disciplines.

You are invited to contribute to the blog and submit posts to the editorial team. Contact Matthias to participate or send suggestions for future posts.

Once again, welcome to the HS blog and we hope you will enjoy it!

The Editorial team.

Wouter Berghuijs I a postdoctoral researcher at the Swiss Federal Institute of Technology in Zurich (Switzerland). His work covers a broad range of topics within hydrology, mostly focusing on hydrological extremes. Previously, Wouter served as the Early Career Scientist Representative of the HS Division, and as the Early Career Scientist Representative of the entire EGU.



Maria-Helena Ramos is a research scientist in hydrology and hydrometeorology at the National Research Institute of Science and Technology for Environment and Agriculture (IRSTEA) in France. Her main research interests are on hydrological forecasting, hydropower and reservoir water management, forecast uncertainty quantification and communication for decision making. She was co-chair of the Hydrological Ensemble Prediction Experiment (HEPEX) from 2014 to 2018, and is president of the EGU Division on Hydrological Sciences since April 2019. http://www.irstea.fr/ramos


Bettina Schaefli is a professor for hydrology at University of Bern (Switzerland). Her work has a strong focus on predicting current and future water resources and related natural hazards across spatial and temporal scales, with currently a strong focus on snow-influenced environments. She was the head of the Catchment Hydrology Subdivision of EGU from 2016-2019 and is an editor of the EGU journal Hydrology and Earth System Sciences.



Matthias Sprenger

Matthias Sprenger is a postdoctoral fellow at North Carolina State University in the United States and the Institute of Environmental Assessment and Water Research (IDAE-CSIC) in Barcelona. He uses stable isotope of water to track water through the critical zone, the Earth’s thin layer spanning from the canopy to the groundwater. Matthias works currently on a DFG-funded project on “Water age dynamics in a Mediterranean catchment and their ecohydrological implications in a changing environment”. He tweets as @MatthiaSprenger


Giulia Zuecco is an assistant professor at University of Padova (Italy). Her main research interests are on the application of tracers (stable water isotopes and major ions) to track water through forested catchments, the hydrology of Alpine catchments dominated by snowmelt and glacier melt and the quantification of subsurface hydrologic connectivity. Giulia works currently on a research project on “Ecohydrological dynamics and water pathways in forested catchments”. https://www.researchgate.net/profile/Giulia_Zuecco