A –Streams of Thought– contribution by Sina Khatami (SK)

Martyn on the summit of Ha Ling Peak, Alberta, Canada

Martyn is a Professor of Hydrology at the University of Saskatchewan, Associate Director of the University of Saskatchewan’s Centre for Hydrology and the Canmore Coldwater Laboratory, Editor-in-Chief of Water Resources Research, and Fellow of the American Geophysical Union. Martyn’s research focuses in three main areas: (i) the developing and evaluating process-based hydrologic models; (ii) understanding the sensitivity of water resources to climate variability and change; and (iii) developing the next generation streamflow forecasting systems. Martyn has authored or co-authored over 150 journal articles since receiving his PhD in 1998.

I was in Vienna for EGU 2019 that I realized that Martyn Clark (MC) is also coming. I decided to ask him for an interview, and so I sent him an email. As thrilling as the opportunity for me was, I got anxious. I was thinking in my head to be professional, ask him good questions, don’t embarrass myself, not to waste his time, etc. Not to mention that an interview with a smart and intelligent scientist can be quite intimidating as well.  Martyn accepted my interview request cheerfully. As we were chatting over email to set the date and venue to meet, my anxiety morphed into comfort and further excitement. We set the meeting details, and his final email to me was “Cool bananas.. see you soon.

SK: Can you tell us a little about your background and education?
How far back do you like to go?

SK: As far as you like.

Ok… I was born in a small farming community in New Zealand surrounded by an abundance of cows [Martyn laughs]. When I first went to the university, I decided that I wanted to be a park ranger, because I loved the outdoors. It turned out that it was not for me. I did my undergraduate degree at University of Canterbury, and then my masters there in snow hydrology. That was in the early 1990s. It was fun actually because I was at the ski area after it was closed. So, they gave me the keys to the ski area.

SK: So, you had a private resort to yourself! [I laugh]

It wasn’t really a resort. It was a club area. So, they had two rope tows. We wore a climbing harness with this contraption called a “nut cracker” that you flick on to the rope. And then you lay back and get towed up the mountain. Each of the rope tows is operated by tractor that sits in the shed at the bottom of the hill. So, I operated that and you know… that was fun. It was a wonderful place to study the snow surface energy balance and water movement through snow. Then in 1995 I did my PhD at the University of Colorado in Boulder. That was going from the site scale to the global scale, because my thesis was on the role of snow cover in the climate system. At that time, I was also doing research on hydro-climatic variability in the Western USA.

After I finished my PhD, I stayed at the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado, which provides a career track for people doing research. I supported myself with soft money for many years there, mostly working on developing advanced methods for probabilistic streamflow forecasting in snowmelt-dominated river basins. In 2006, I went back to New Zealand to build a flood forecasting system; in 2010 I came back to Boulder and started working at NCAR to build a program on climate and water. In December of 2018 I moved to University of Saskatchewan in Canmore.

SK: What inspired a park ranger enthusiast to become a scientist, particularly a hydrologist?

Well, I haven’t always wanted to be a scientist. My main interest in going to park ranger school was because I love the mountains. I was mostly a mediocre student through most of my high school education. Because I loved going out to the mountains more than studying. Even through my undergraduate, I was kind of an average type of student, because I spent a lot of time in the mountains. At that level I didn’t really adhere well to the structure of the education. I didn’t necessarily fit into the box. I originally gravitated towards park ranger school because I love the outdoors, and studying hydrology was a way to study natural processes. I did my master thesis in field research in the Southern Alps in New Zealand, which are spectacular. So originally, the science was an excuse to be outdoors but as I was going through university, I became more interested in the science as well.

SK: And in this journey of yours, what were the major hurdles along the way, and where did you find inspiration to overcome them, to become who you are now?

I didn’t really experience too many hurdles in the early days. I did my undergraduate degree at the University of Canterbury in New Zealand. I decided I wanted to do a Master’s thesis, and I did my masters at the same place. I really enjoyed the research. I had a good support network. My advisers were very good at that time. Then when I went to apply for PhD programs, I really had no idea what I was doing [we both smile]. So, you know, a lot of it was luck. I looked at two PhD opportunities: one was at the University of Colorado at Boulder and one at the Arizona State University (ASU) in Phoenix. I wrote an application for both of those places. But you know it was a lot of money to apply for those schools. I was a poor student in New Zealand, and I didn’t have a lot of money. University of Colorado told me that they accepted me the day that I was about to post my application to ASU. So, I kept the money and went to Colorado [Martyn laughs]. I had no idea really about the difference between those two universities — but the mountains in Colorado are spectacular.

SK: I was about to say…

MC: It was the right place to land! [he says with a smile]

SK: Your research spans across a wide range of domains of hydrology, hydro-climatology and model development. How did you expand your knowledge and expertise so widely?

In the early days, it was more of a random walk. My interests evolved into different areas and I pursued opportunities where they were. I read a lot. Even when I was doing my master thesis, I read and read and read. So, I was able to get a fairly good understanding of the literature and identify what the major science questions are. Later on in my career, I’ve been much more strategic than tactical as I was in early stages of my career: thinking about what the big problems are that we want to solve, and how we can go for the funding opportunities out there that lead more towards this larger vision… more of a proactive approach, than a reactive one.

SK: Over the past few years, you’ve become the Editor-in-Chief of WRR (which is an enormous commitment), moved from public sector (NCAR) to academia and from Colorado to the Canadian Rockies. Each of these decisions are big enough to be a challenge for a few years. So, first, how’re you holding up [I laugh]? And what motivated such major changes?

Well these were more sequential than simultaneous [we laugh]. So, let’s deal with them sequentially. I was asked to apply for the Editor-in-Chief position for WRR. They had a search committee together and they asked me if I would consider doing it. My initial response was no. Then I thought about it for a while. Two things had happened in that year. First, I was promoted to senior scientist at NCAR, which is the top level there. So, I didn’t have any opportunities for additional promotion. And also, I was elected as Fellow of AGU. So, I thought I have kind of established myself in my career and perhaps now is the time to give back to the community more. And there was this opportunity. I was weighing all of my commitments and then thinking about how I could push the field forward. And I thought, well… what good can I do? I thought if I publish, say, two fewer papers a year and be the WRR Editor-in-Chief instead, I can probably do more good and continue along my current trajectory. I was also keen for a new additional challenge.

NCAR is federally funded research and development centre and received a lot of its funding from government and through NSF (National Science Foundation in the USA). The decision to move to the University of Saskatchewan was in part because I wanted the broader challenges that comes with the university setting. And it was in part because of the funding that they already had in place with the Canadian government as part of the Global Water Futures (https://gwf.usask.ca/) programs. This really provided the opportunity to achieve a lot of my research ambitions that I’ve had for many years.

SK: Have these new roles and changes impacted your research?

Being the WRR Editor-in-Chief gives me a broader perspective. I find it easier to identify what the key science questions are that we need to address as a community, because I see so much [of the current research being done].

SK: How many papers do you read on a daily basis?

MC: It depends how you define read?

SK: Handle let’s say.


SK: And some of them interest you to look deeper into them?

We are getting close to 2000 submissions a year. All papers come to me, first. Then, I will either ask another editor to handle a paper or I handle it myself. So, every paper I will at least skim through to figure out what the topic is, what the research questions are, what the conclusions are, check the figures to see to what extent they support the research questions and conclusions. But I read in more detail the papers that I handle.

SK: Gaining this bigger picture of the research community is probably influencing your own approach to defining new questions, particularly for your new career line at University of Saskatchewan.

Yes. For my new career at the University of Saskatchewan at Canmore, a wonderful location by the way, we are building up the research program there (https://uofs-comphyd.github.io/). A lot of the research thrusts and the Global Water Futures program are the things that I have been working on over the past twenty years anyway. It is dominated by two main application questions: (1) improving streamflow forecasting methods, and (2) improving assessments of impacts of climate change on water security. Those are the two applied questions that have guided my research on process understanding, model development, strengthening the link between algorithms and theories, etc. It is not as if I’m going to a new research area; I’m going into an area where I have had an extensive presence for a very long time. So, that part of it is not new. But the part that is forcing me to extend myself a little bit is that the funding available is more than an order of magnitude larger than what I ever had before. So, being able to think more strategically, like build up a large cadre of postdocs to answer these questions, or how to orchestrate a large research program — it is really exciting.


View of one of the mountain ranges near Canmore, showing (l-r) Mt Lougheed, the iconic Three Sisters, Ship’s Prow, Mt Lawrence Grassi and Ha Ling peak, where the leading photo of this interview was taken 

SK: Are there any skills you have crossed over from NCAR that you developed uniquely within that work environment, but which will now contribute to your new role in academia?

I think the Global Water Futures program is unusual in the sense that academia does not normally have that large a program. The size of the program is more similar to what you see in a public setting. So, the skills that I had in terms of managing a large team and pushing them forward are easily transferable. The skills that I need to learn is working with students. I haven’t had many interactions with students. I finished my PhD in the mid-1990s and at NCAR and other places that I worked I supervised postdocs, career scientists and other people like that. I have been able to push those people forward but now I am beginning to work with people who are the beginning of their careers. It is something that I don’t have much experience in, and I am really looking forward to it.

SK: Looking back at your research career, what do you think your major breakthroughs are and why?

I think my major breakthrough is quite broad. But I can list some specific papers if you want. Developing a more structured approach to hydrological model development is something that I’ve been working on for many years. The first paper that I really published in that area was my FUSE paper (Clark et al., 2008), working with bucket style models. Then my most recent big modelling paper was my SUMMA paper (Clark et al., 2015a, 2015b) [both are modelling frameworks that allow a user to analyse the impact of individual modelling decision; such as the choice of model structure, the choice of specific flux equations, and the choice of numerical method with which to solve the model equations].

SK: Any interesting or inspiring stories about them that you like to share with younger hydrologists?

I’m not sure if it’s inspiring, but it could be interesting [we both laugh]. I view the SUMMA paper, a two-part paper, as my best paper that I’ve ever written. It’s also the only paper that I ever had rejected.

SK: [I laugh hysterically and ask] on what grounds was it rejected?

On philosophical grounds, not on any of the technical details. The approach that we were proposing challenged some of the reviewers and the reviewers challenged me. But I think that was a good thing. We got a really rigorous review. The reviewers really challenged us to sharpen our message.

SK: And you are happy that you had that challenge, because you think it improved the paper?

Oh, it really improved the paper a lot. I’m really grateful to the reviewers of the paper, to spend the time that they did in order to help us strengthen the paper.

SK: How do you describe your research style? Or, what are the main elements for you when you’re impressed by a piece of research?

For me, personally, I’m really interested in making a step change in our modelling capabilities. So, most of the major papers that I’m proud of have had a gestation period of more than five years. And so, if you look at my publication history — it’s kind of interesting — I had no first-author research publications in the time period of 2011 to 2015, when I was developing SUMMA. And that can be a little bit dangerous [he laughs] for people at earlier stages of their career. I really wanted to make a major contribution in the way that we develop models. I was worried that a lot of our model development was somewhat ad hoc, and we didn’t have the structure that we needed in order to really understand where and what model weaknesses are. I was worried that model evaluation wasn’t done in a controlled way and that we really needed a new framework in order to push forward in those areas.

SK: On that note, would you say that creativity and success are correlated or not necessarily?

I think they are. I think you need to be creative, but you also need to be bold. So, it depends on how you view creativity. You can view creativity as a clever twist on an existing idea.

SK: And what do you exactly mean being bold?

Take the steps that are necessary to advance our capabilities. Don’t settle for incremental advances. Incremental advances are important, but they need to be conducted in the context of achieving a larger scale change.

SK: What would you identify as the main gaps or big picture questions of hydrological sciences for the coming decades that you think early career scientists can pursue?

I think we really need to evolve towards a more interdisciplinary Earth System Science approach to modelling. For many years, hydrology has been rooted somewhat in what was called rainfall-runoff modelling. That term is not really applicable anymore, because we now are modelling a large number of complex interrelated processes in the terrestrial water cycle. So, multi-process modelling in an Earth System modelling context, not just focusing on the short-term fluxes but also the longer-term evolution of our systems. Understanding the evolution of soils in the catchment, understanding the evolution of vegetation in the catchment and understanding how those slowly varying processes feed back on to the higher frequency variability, which has typically been the domain of hydrologists.

SK: And this goes back to the SUMMA paper that you mentioned?

Well that’s just a part of the bigger picture. SUMMA has a more complete representation of the terrestrial hydrological cycle than many hydrological models. But many models already have that level of complexity. SUMMA doesn’t even begin to get into the issues of bio-geochemistry, catchment co-evolution, etc., which are going to be really important. What SUMMA does is provides a structured template for process-based hydrological models which can be extended into the Earth system modelling framework. But it’s nowhere near complete enough of what we need moving toward. So, what I’m talking about is not something that we can do in the next couple of years but something that we need much more concerted effort over the timescales of several decades.

SK: Are there any papers or books that you would like to recommend on this grand idea of expanding the spectrum of processes within current hydrological models towards Earth system modelling?

The first part of the SUMMA paper (Clark et al., 2015a) provides some beginning thoughts in that area but it doesn’t go as far as it needs to. We wrote a paper on improving the representation of hydrological processes on Earth System models (Clark et al., 2015c). That’s really just beginning to scratch the surface as well. I think the paper that everybody should read is the one by Fan et al. (2019) on providing the link between hillslope hydrology and Earth system modelling that provides lots of pointers in that direction. But it’s funny that you ask that. There’s something that I’ve been kind of stewing on for a while, which is to put together a coherent commentary paper that emphasizes the research direction that’s necessary.

SK: What are your main hobbies besides work, especially nowadays that you have a lot on your plate?

Well we love the outdoors! As I mentioned to you at the beginning of the interview, I spent a lot of my childhood in the mountains. We were riding up our bikes up to the Southern Alps in New Zealand and would go backpacking for several days. Actually, in New Zealand, we call it tramping, not backpacking. In New Zealand, and I guess everywhere, there were two ways that you could advance. You could graduate from a tramper either into a hunter or into a climber. I started getting into a lot of climbing and did a lot of rock climbing. That’s been my hobby for many years. That’s kind of decreased over time you know as I’ve got busier and as we now have kids, we’ve been looking for activities that were more suitable for the family. But it’s something that I’m beginning to get back into… [he pauses and then says with a smile] My strength to weight ratio isn’t quite what it used to be [we both laugh], so that’s a little bit more challenging. But we have hired a senior hydrologist to come to Canmore, and he’s made it clear that he expects to be dragging me up mountains and he’s told me in no uncertain terms that I need to get myself in shape before his arrival.

SK: So, how do you manoeuvre between work and life to balance them out?

Sometimes poorly. I’ve found what works for me, but this doesn’t work for everyone. I do a lot of work in the early mornings. So, I would often go to bed quite early and wake up early in the morning. Then a couple of hours of work before breakfast, before the kids get up. When I first started WRR, I was getting up at 4:00 a.m. every morning. I did that for a period of time, and then I found that unsustainable. So, it’s more like 5:30 or 6, and I really begin to make some progress before the day starts. When our kids were young, it was more difficult to balance work and life. Now that they’re getting older, they’ve got their own interests and it’s more acceptable for me to open up the laptop on the couch on the weekend and begin to get some work done.

SK: You’ve pointed out many great things so far, is there any other advice you may have for young hydrologists?

I think I’ve covered a lot of it already. Be bold. Think about how you can really make substantial advances in the research frontier. Be strategic. You need the incremental progress. You need the intermediate scale products as you are conducting your research so that you can feed the beast [he smiles] and work effectively through the career track. But those intermediate scale products need to be conducted within the context of a larger scale vision. So, really think about defining that vision. Talk about that with your colleagues and keep refining that. And having an idea how your career contributions will really begin to make a difference.

Some guidance would be to think about three levels of strategic planning or technical planning in some respects: (1) what do you want to accomplish in your career? In terms of always keeping that and the longest timescale. (2) What’s the thing that you’re going to present at the next conference? Most people are thinking about those two or perhaps not giving as much attention to the vision aspects as they should. But the third that often gets neglected based on my interactions with people is (3) what are you going to do tomorrow, and the coming week? So, basically organizing your activities on the shorter timescale, so that they are feeding the ambitions that you have on the longer timescales, I think is really important.

SK: This might be a somewhat stupid question. Do you have any measures to evaluate a good PhD or postdoc? Like the number of their publications or good publications in a year, etc.

Yeah, this has been my problem. I don’t like the way that people are being judged in academics. There’s a saying that managers know how to count but they don’t know how to read [we both laugh]… In the sense that people are focused too much on outputs, like how many papers you published, than outcomes. I think that things are going to change. I wrote an editorial in WRR on the citation impact of hydrology journals (Clark & Hanson, 2017). There I was talking about the need to shift away from quantitative assessments to more qualitative assessments to really begin to measure how people are making a difference in the community. For me that’s the major thing. So, if we get back to what would help people get a job, I can tell you what I’m looking for. Yeah, you need some papers to get on people’s radar screen. If you have finished your PhD and you don’t have any papers then that’s a red flag. But what you really need, in my mind, is to be known for something. That people look at you and say okay that person has done X, or that person has accomplished Y. So, the number of papers that you’ve written become less important. So, what I’m looking for is what have you done to make a difference in the community. And that’s what a lot of other people are beginning to look for more.

SK: I’m curious to know more about this. How would this qualitative assessment process work, to assess the impact of a person on hydrological sciences or even the broader geosciences?

You should read the Declaration on Research Assessment (DORA) [https://sfdora.org/read/], which I also referred to in our 2017 editorial (Clark and Hanson, 2017). DORA comes up with a set of guidelines for funding agencies, universities, managers, etc. to show how they can move towards research assessment practices that are more fair. It has been picked up by a lot of different institutions and universities. A lot of it is there. It’s more just changing the structure of the research assessment. You know there’s not going to be one size fits all template that people can use but structuring it in a way that emphasizes the contributions rather than the specific papers. It takes more work, but we should value our colleagues and take the time to really make sure people’s efforts are directed in productive ways.

About the author

Sina Khatami (@SinaKhatami) is currently the Secretary of Young Hydrologic Society (YHS) and an Editor of YHS Blogs. He is also a committee member of AGU’s Hydrology Section Hydrological Uncertainty Technical Committee since 2018, and Student Subcommittee (H3S) since 2017. Correspondence to sina.khatami@unimelb.edu.au


Clark, M. P., Slater, A. G., Rupp, D. E., Woods, R. A., Vrugt, J. A., Gupta, H. V., … & Hay, L. E. (2008). Framework for Understanding Structural Errors (FUSE): A modular framework to diagnose differences between hydrological models. Water Resources Research44(12).

Clark, M. P., Nijssen, B., Lundquist, J. D., Kavetski, D., Rupp, D. E., Woods, R. A., … & Arnold, J. R. (2015a). A unified approach for process‐based hydrologic modeling: 1. Modeling concept. Water Resources Research51(4), 2498-2514.

Clark, M. P., Nijssen, B., Lundquist, J. D., Kavetski, D., Rupp, D. E., Woods, R. A., … & Rasmussen, R. M. (2015b). A unified approach for process‐based hydrologic modeling: 2. Model implementation and case studies. Water Resources Research51(4), 2515-2542.

Clark, M. P., Fan, Y., Lawrence, D. M., Adam, J. C., Bolster, D., Gochis, D. J., … & Maxwell, R. M. (2015c). Improving the representation of hydrologic processes in Earth System Models. Water Resources Research51(8), 5929-5956.

Clark, M. P., & Hanson, R. B. (2017). The citation impact of hydrology journals. Water Resources Research53(6), 4533-4541.

Fan, Y., Clark, M., Lawrence, D. M., Swenson, S., Band, L. E., Brantley, S. L., … & Kirchner, J. W. (2019). Hillslope hydrology in global change research and Earth system modeling. Water Resources Research, 55(2), 1737-1772.

Hallway Conversations – Martyn Clark

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