Thomas Dunne

Bren School, University of California Santa Barbara

2016 Robert E. Horton Medal Winner

Thomas Dunne was awarded the 2016 Robert E. Horton Medal at the AGU Fall Meeting Honors Ceremony, held on 14 December 2016 in San Francisco, Calif. The medal is for “outstanding contributions to hydrology.”


This is an award that is long overdue. Tom Dunne has been a major influence in hydrology and geomorphology for the past 40 years in a variety of environments, from Vermont to East Africa, the Andes, and the Amazon. Tom’s methodology has been instructive regardless of the domain of his research. During a period when there has been a tendency for researchers to concentrate either on experiments or on computer models, he has always, like Robert Horton, aimed to transfer the knowledge obtained from careful field experiments to the appropriate representation of processes in models. Tom has done this in an exemplary way: runoff generation mechanisms (from hillslopes to the entire Amazon); channel networks (landscape evolution and river habitat); weathering, hillslope erosion, sediment routing, and sediment budgets; river mechanics, meandering, and floodplain depositional processes; and watershed management and river restoration. He has done so at scales from small plots to the Amazon. At times his methods have been unorthodox, such as his approach to simulating the effects of cattle on infiltration rates in East Africa (which makes for a highly entertaining seminar that inspires students).

Tom is a true research scientist, but that has not meant that he has neglected the application of the science to practical problems—that is essentially what his book with Luna Leopold, Water in Environmental Planning, is all about.  He has also been prepared to devote time to the wider interests of the hydrological and geomorphological communities, serving on numerous national and international committees, including working for the United Nations.

All of the supporting letters refer to Tom’s inspiring influence on his students and younger colleagues. In his case, it can really be said that he has nurtured them through his intellectual curiosity, by his active contribution to their fieldwork, and via the weekly paper discussion (or dissection) sessions at his home.  Many of those students have, of course, gone on to be outstanding hydrologists, geomorphologists, and ecohydrologists in their own right.

Tom’s name is already linked to that of Horton through the descriptions of Horton and Dunne overland flow mechanisms in hydrological textbooks.  As Bill Dietrich expressed in his supporting letter, “He took up the charge of Horton’s ‘hydrophysical’ approach and contributed many fundamental insights about surface processes and landscapes. Our understanding of hydrology and geomorphology has been greatly advanced by both his scholarly publications and his intellectual leadership.”

—Keith Bevin, Lancaster University, Lancaster, U.K.


Thank you to Keith Beven and the other supporters of this nomination for providing me with such an honor, and to the audience for letting me enjoy it with you. The heartwarming aspect of the award is that it reminds me of the influences of the communities and institutions in which I have been fortunate to participate. The geography departments at Cambridge and Johns Hopkins impressed on me the importance of constructing theory based on field investigations (working on what Keith frequently emphasizes are our epistemic uncertainties about how landscapes function), and of spending at least a portion of one’s research efforts on topics of societal value. Nairobi and McGill Universities exposed me to the subarctic and tropics, expanding my appreciation of the environmental range of Earth. And in the multidepartmental communities at the Universities of Washington and of California, Santa Barbara colleagues strengthened my geophysical education and expanded the geographical range and time depth of my studies and also my interest in hydrologic and geomorphic contributions to environmental conservation and restoration from the Pacific Northwest to the Amazon Basin. I am mindful that it was possible to learn new things in all the roles I had in these institutions from undergraduate to aging professor. I learned that diversity of scientific approaches and of geographical exposure is valuable and enriching.

But this is also a night to reflect on Robert Horton. He has guided me since my undergraduate days when I was taught that his hydrophysical approach was the key to understanding the fluid mechanical processes driving the formation and hydrological functioning of landscapes. I had to be informed later of the roles that Earth plays in providing the material properties, boundary conditions, and time frames in which those landforms and those functions evolve. But Horton has broader lessons for all of us. He distilled his working engineer’s experience as an observer of nature and his multi­lingual reading into foundational studies across the processes and scales of the hydrologic cycle. In the 1930s, he published a scientific agenda for hydrology and was a ­­­co-­founder of the Hydrology section of AGU in the face of considerable early skepticism about whether hydrology was truly a scientific field. For that, we should be particularly grateful to Robert Horton for providing us with this community and with an opportunity to ask continually whether our own work supports his optimistic vision of what we might accomplish.

—Thomas Dunne, Bren School of Environmental Science and Management, University of California, Santa Barbara