Hydrological Sciences

Hydrological Sciences

YHS interview Thorsten Wagener: being the head of a research group is “a bit like being a football coach”

In its “Hallway Conversations” series, the Young Hydrologic Society has recently published an interview with Thorsten Wagener, who is currently professor and the head of the Water and Environmental Engineering research group at the University of Bristol, UK. The interview was conducted by Wouter Knoben, a PhD student at the University of Bristol. With their agreement, we reproduce below some short extracts of the interview. For the full interview, visit the YHS Blog (here).

What’s an unusual place where you find inspiration for yourself or the work you do?

Football! Playing (in the past), watching and reading about it. [Points at bookshelf] that’s my football bookshelf. My current role, as Professor and Head of a research group that includes 9 academic staff and many more students and postdocs, is – at least in my head – a bit like being a football coach. Your team is a group of highly talented individuals who have all self-selected to be here as top people in their own right (like a professional football team). The role of the coach is to get them all to somehow work together or at least benefit from each other, without losing the chance to shine individually. So, I have a whole bunch of books written by or about football coaches on my shelf. Including “My Turn” by Johan Cruyff, “Quiet Leadership” by Carlo Ancelotti and “Leading” by Sir Alex Ferguson. Teams follow coaches because they believe that the direction the coach suggests will bring them success. There is a need to be convincing, genuine as well as caring – otherwise players will not believe that you want them to succeed, but that maybe you are only looking for short-term success for yourself. That’s more the Mourinho strategy, which always fails after a couple of years when players get disillusioned. I try not to do that here but try for everybody to benefit from the group.

Could you share any insights on how you approach creativity? Do you think that creativity and success are correlated?

Creativity is a bit under-appreciated in research, I think. I like learning about how creativity is approached in other fields. There is an excellent book called “Creativity Inc.” by the former President of Pixar, Ed Catmull. He discusses how they spend decades trying to optimise their creative process. They decided that everybody should share ideas early, so that bad ideas would fail quickly and not waste time, and that they needed to create continuous opportunities for feedback and involvement of everybody. We, in science, often see creativity as a by-product when it really is the essence of research. We often see it as a gift that one has or does not have, rather than something that can be significantly improved and nurtured. I think that in research, success and creativity are closely related and that everybody can improve their ability to be creative. I think that the most influential hydrologists are also the most creative. People who I admire for their creativity include (but are of course not limited to) Hoshin Gupta, Keith Beven, Chris Duffy or Brian McGlynn. Very different personalities, all of them (apart from maybe Chris Duffy) not the best students during their undergraduate degrees, but very creative people who can think outside the box and in a different direction than the rest. I think the distinction between short-term and long-lasting scientific contributions is often due to differences in creativity, but I should stress that it is not just that. Others succeed through their energy, through their persistence or depth of knowledge.

What are the biggest challenges and opportunities for hydrologists in the next 10 years or so?

One big challenge is that we need to not lose track of the large societal questions. Hydrologic understanding was and is the foundation for our survival and for sustainable development. Without water, there is no energy, no food, no clothing. The spreading of many infectious diseases is closely coupled to the water cycle. We cannot understand most local climate change impacts without understanding hydrology. There are many opportunities for hydrologic knowledge to contribute to society.
However, hydrology is also complicated because the closer you look at our environment, the more complex it becomes. So, as hydrologists we have long focused on understanding this complexity. Now, we need to start tackling the big problems and clearly separate the work on technical details (regardless of whether this is related to models or measurements) and focus on big societal questions. We are very good on tackling the former; we have historically been rather poor in identifying the latter (including the role of hydrology in understanding them). People like Tom Gleeson or Mark Bierkens have shown that we – as hydrologists – can identify big scale problems and provide answers – though they might be more approximate than what we can say about specific catchments. Don’t get me wrong. I am not suggesting that we focus only on this, but that we simply have to do significantly more of this type of work. Here is where we need to be more creative: in identifying interesting and relevant problems and questions – as well as solutions.

Read the full interview in the YHS Blog (here).

Edited by Matthias Sprenger

“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”.

Talking hydrology: an interview with Jana von Freyberg on her work in the Rietholzbach catchment

Talking hydrology: an interview with Jana von Freyberg on her work in the Rietholzbach catchment

This is the first post of “Talking hydrology”, an interview-based series of posts in the HS Blog that present the experience and personal views of hydrologists and people interested in talking about hydrology. The “Talking hydrology” series is edited by the team of the HS blog together with Leonie Kiewiet (University of Zurich, Switzerland).

Here, we will talk about experimental hydrology, which focuses on hydrologists who work in different experimental catchments across Europe and beyond.

We interviewed Jana von Freyberg, a post doc at ETH Zurich (Switzerland). She talks about her experience in experimental hydrology in the Rietholzbach catchment in Switzerland, where she carried out her PhD work.


1- When were you introduced to experimental hydrology? What was the most exciting memory that you have?

I made my first hydrological and hydrochemical measurements in the field during my undergraduate studies at TU Berlin during a 1-week excursion in Bavaria, Germany, led by Traugott Scheytt. The goal was to compare the flow regimes and water quality of two streams that originate from very different geological systems. This initial field work experience was an exciting introduction to experimental hydrology and hydrochemistry since I conducted every step (planning, sample collection, analysis, data interpretation) myself in a short amount of time. It was also a great experience to work together in a group and to gradually improve our field-work skills. Only after this excursion did I realize how much can be learned about the subsurface properties of a catchment by studying the flow regime and hydrochemistry of streams.


2- During the PhD you carried out most of your research in the Rietholzbach catchment, which is a long-term monitored catchment in Switzerland. What were the main objectives of the research at the beginning of the hydrological monitoring?

In most mountainous headwater catchments, recharge, storage and discharge of groundwater strongly control streamflow regimes and stream water quality; however, experimental data in these regions are sparse and hydrogeologic processes are often ignored or simplified in conceptual catchment models. Therefore, in my PhD project, I studied the dominant drivers of groundwater recharge (i.e., climatic forcing and landscape properties) and the responses driven by groundwater discharge (i.e., streamflow generation and solute transport) in the Rietholzbach catchment. For this, I installed a spatially-distributed groundwater table monitoring network, conducted geophysical measurements and performed repeated sampling campaigns. In addition, I benefited greatly from the existing research infrastructure and I am thankful to the group of Prof. Sonia Seneviratne for sharing data they collected in the Rietholzbach catchment.


3- What are the current objectives of the research in Rietholzbach? How have these objectives evolved in the years?

Hydrological research in the Rietholzbach catchment began in 19761, when it was equipped with three streamflow gauging stations, a meteorological station and a large weighting lysimeter. At this time, the general objective of the research program was to provide an experimental database for studying hydrological processes in a nearly pristine environment. Specifically, fundamental research was carried out on quantifying and simulating preferential water flow through soil macropores at the plot scale. At the catchment scale, several numerical (e.g., DIFGA, PREVAH, WaSIM) and conceptual models (e.g., J.W. Kirchner’s simple dynamical systems approach) have been developed to characterize the flow and transport pathways of water through the landscape.

Since 2007, the research group of Prof. Sonia Seneviratne (Land-Climate Dynamics, Institute for Atmospheric and Climate Science) at ETH Zurich has been maintaining the site. Their focus is on soil moisture and evapotranspiration measurements and they also investigate mechanisms leading to climate extremes such as droughts and heatwaves.

In addition, several researchers, including myself, perform related research at the site. These projects focus on the temporal changes in stream networks (Gianluca Botter from University of Padova in collaboration with Mario Schirmer from Eawag), as well as on the role of landscape and climatic properties on stream water ages2.


4- What kind of advantages and challenges can be encountered while collecting data for a PhD or a post doc project?

To me, data collection in the field is always a unique learning experience that cannot be replaced with reviewing literature or modelling. Because I was responsible for data collection and data post-processing during my PhD, I knew exactly where the data came from and which data I could trust. While being in the field, I have experienced the catchment landscape, the weather, the hydrological features (such as springs, river channels, wetlands), and thus gathered “soft data” that are useful for performing the most informative measurements and for developing a conceptual idea of how the catchment functions.
I have also learned how to plan and conduct field campaigns that often involved several people. Today, I heavily rely on these skills for my postdoctoral projects that involve field work, for planning Master’s thesis projects, as well as for writing grant applications in which I need to provide detailed information about the proposed sampling design.

In my opinion, the biggest challenge of field work is the time needed for organizing and conducting sampling campaigns, troubleshooting, and for collecting enough data that permit robust scientific analyses. Unforeseen things happen (such as mice biting through the cables of my soil moisture probes) that require quick reactions and some technical skills to avoid data loss. I further spend quite some time with data post-processing and database management. In addition, the costs for installations, the monitoring equipment, as well as laboratory analyses of water samples can be quite high.


5- What kind of advice would you give to early career scientists approaching field work?

Take your time before you start data collection. An important advice to all early-stage PhD students is to spend some days in your research catchment to familiarize yourself with the landscape and the existing infrastructure (accessibility, private wells, irrigation, etc.) and to talk to the local residents so that they get to know you and your project. Once you start data collection you are more or less bound to your sampling sites and you might be limited in exploring other (maybe more interesting) parts of your study catchment.

Don’t give up too easily. The first installations or measurement campaigns are never perfect and you will learn as you proceed with the data collection. I have found it useful to talk to other field hydrologists about their approaches and to participate in workshops and summer schools (e.g., Catchment Science Summer School3) to learn how field work is done in other catchments.

Field work is always more fun if not done alone. Having a PhD colleague who is involved in your project would be optimal to share ideas, conduct field campaigns and discuss data. Alternatively, you could (co-) supervise a BSc or MSc thesis project in which the student collects and analyses a subset of your data.

It is very important to set a deadline for data collection. It seems tempting to collect more data during some last big storm event or to do one more tracer test, however, it is very likely that those data that you have collected in the last years may already be the most representative for your site.

Learn how to set-up and to manage a database. Because I used a variety of temporal high-resolution data sets from different sampling locations, I used a relational database which allowed for efficient querying and plotting of the data. This was particularly useful when I needed to retrieve specific data sets for colleagues that have used these data for model calibration. Organizing your data in a relational database further allows data to be easily publicly available after the end of your PhD. Thus, your data will potentially be of great use for site-to-site comparison studies, model testing and for sparking new research ideas.


6- Have you ever wondered how experimental hydrology could evolve in the next few years? What kind of hypotheses should be tested? And what kind of groundbreaking instrumentation or methodologies are needed to improve our knowledge of hydrological processes by experimental data?

The heavy isotopes of water (18O and 2H) have been used extensively over the last decades as environmental tracers, and we have learned a lot about the age composition of the streamflow hydrograph during storm events. I am excited about new technological developments that combine membrane systems with field-deployable isotope analysers, with which we can continuously monitor short-term isotopic variations not only in stream water and precipitation, but also in soils and tree xylem. These new methods provide important information about water fluxes between these water pools that otherwise remain missing if measurements are made only occasionally and at some specific locations, such as at the catchment outlet.

Secondly, ‘wireless sensor networks’ now allow for spatially-distributed, continuous measurements of numerous hydro-climatic variables. Because environmental sensors and loggers have become cheaper, smaller and more energy-efficient over the last years, we now can install many of these sensors across much large catchment areas. Digital wireless data communication networks allow for transmitting these sensor data directly to a local data storage unit or a cloud service so that data collection will be less time consuming and risky. Wireless sensor networks will prove to be very useful in high-altitude, snow-dominated catchments to quantify spatio-temporal changes in snow storage, as well as in forested landscapes to monitor subsurface water-vegetation interaction in response to climatic variability.

Lastly, while generating complex and large data sets with distributed sensor networks might be a primarily technical challenge, the statistical analyses of these data requires advanced programming skills. Thus, experimental catchment hydrologists that use wireless sensor networks for data collection may benefit from collaborating closely with data scientists who are experienced in building pipelines for the analysis of very large and noisy semi-structured data sets.


Thank you, Jana, for your time and insights in experimental catchment hydrology!
For more info, the reader can visit the Rietholzbach catchment website or contact Jana von Freyberg.


References and web links
1 Seneviratne S.I., Lehner I., Gurtz J., Teuling A.J., Lang H., Moser U., Grebner D., Menzel L., Schroff K., Vitvar T., Zappa M., 2012. Swiss prealpine Rietholzbach research catchment and lysimeter: 32 year time series and 2003 drought event. Water Resources Research, 48, W06526. DOI:10.1029/2011WR011749
2 von Freyberg J., Allen S.T., Seeger S., Weiler M., Kirchner J.W., 2018. Sensitivity of young water fractions to hydro-climatic forcing and landscape properties across 22 Swiss catchments. Hydrology and Earth System Sciences, 22, 3841-3861. DOI:10.5194/hess-22-3841-2018
3 Catchment Science Summer School

EGU is a bit like a music festival: first time experience of an ECS in hydrology

EGU is a bit like a music festival: first time experience of an ECS in hydrology

EGU is a bit like a music festival. Maybe not as crowded as the Donauinselfest, but you’ll definitively experience some of this type of event classic features: dilly-dallying a lot about what to see next, losing your friends and setting up more or less detailed meeting points, buying overpriced food and beverages. And if in the right place at the right time, you might even see some actual “rock stars”!

Me and my Mentor!

EGU is a lot of people and a lot of contents squeezed into one week! Now it can be quite unsettling for newcomers, but here’s some points to demystify the beast.

Despite the ants-like flow in the hallways, EGU recovers human dimensions during each oral session, with an average attendance of about 40 people for what I could experience. It’s something to have in mind when getting nervous about your own scheduled presentation if there’s any.

Half of people is like you, meaning young scientists, eager to share and help each other. And fortunately, the other half is just the same, with more experience and possibly less hair that’s all. Communicating is very easy at EGU, with all kind of researchers (age-wise, country-wise, topic-wise). That’s probably the main purpose of it and the main reason you should come.

There’s also a bunch of events and special groups intended for facilitating new scientists’ integration: Sunday evening Ice-breaker, Early Career Scientists lounge, short courses and workshops and social evening events, etc. In particular, when registering for the EGU General Assembly, you’ll be asked if you want to be part of a Mentoring program. Say yes and you’ll be put in touch with a more experienced participant that’ll give you further advice and with whom you can meet easily throughout the week. I experienced this mentoring to be a good way to get comfortable in the unfamiliar terrain of such a big conference!

Now, how to make the most of this week you may wonder. Well there is no right answer to that I suppose, but here’s some input.

Red poster hall – the heart of hydrology during the EGU week.

Quoting approximately the EGU’s president introduction speech, go beyond your own field of research. It would be a shame to spend a whole week focusing on what you’re working the rest of the year anyway, when so much is at hand. As for myself (doing a PhD on computational methods in hydrogeology), I attended sessions about surface water quality, erosion processes, ecology, geothermal resources, or science-politics linkage (this last inspired me some thought that I’ll may be able to share with you later). At some point lost in the program and venue, I even stumble about a speech about hyper arid environments, where I heard that some place in Chile receive less than 1 mm of precipitation a year… things you learn when you get lost!

And to conclude, you might feel obligated to spend 10 hours a day in the Vienna International Center, with regard to the plethoric program. Well I do think that it should be judged by your own ability to concentrate and digest information in a little amount of time. As far as I’m concerned, I chose not to fully book every day with session, sparing some time to rest, wander and visit! Mind that Vienna is a key European historical and cultural center: the apogee of classical and romantic music genres, one of the birthplaces of modernism in painting and architecture, a land of authors and philosophers to be discovered.

Edited by Matthias Sprenger


Guest author Dimitri Rambourg attended this year’s EGU General Assembly the first time and he shares his impression. He is a PhD student at Laboratoire d’Hydrologie et de Géochimie de Strasbourg (LHYGES) in France.