Jeffrey J. McDonnell

The 2009 John Dalton Medal is awarded to Jeffrey J. McDonnell for his distinguished contributions to experimental hydrology.

Jeff McDonnell presently holds the Richardson Chair in Watershed Science at Oregon State. He has an international reputation as an exceptional scientist, a charismatic teacher and an influential world leader in watershed hydrology, achieved through groundbreaking research experimental rainfall-runoff studies, isotope hydrology, hydro-biogeochemistry, hydrologic theory development, and watershed modelling. His research has focused on understanding basic hydrologic processes in terms of where water goes when it rains, the multiplicity of pathways that it follows on its way to the stream, and the distribution of residence times of that water along these pathways. While basic, these questions have served to define new conceptualisations of runoff behaviour based on the field research that he has carried out in watersheds in Canada, USA, UK, Sweden, Germany, Japan, New Zealand and China. As early as 1993, a review of forest hydrology (Bonell, 1993; Journal of Hydrology, 150: 217-275, quoting from pg 232), said that, “more field experiments, coupled with laboratory work, on the lines of McDonnell (1989; 1990), are urgently required”. Since that review was written, Jeff McDonnell has fully grasped this challenge and literally has led the field of experimental hillslope hydrology, developing along the way new theories of hillslope hydrology centring on threshold behaviours, the role of the riparian zone in nitrogen cycling and transformation, and on connectivity, particularly how different landscape units connect and disconnect in time and space. He has led the hydrological community towards a paradigm shift in hydrological thinking, towards acceptance that stormwater in the stream, despite its rapid response to storm rainfall is composed largely of water stored in the catchment prior to the event. This so-called old water paradox is already beginning to challenge and redefine watershed modelling and standard water resources engineering applications. He has stressed a new approach where experimentalist and modeller interact so as to better understand and model hydrological processes. Jeff McDonnell’s work has influenced a range of related fields from biogeochemistry to stream ecology and geomorphology, and serves as a bridge between traditional fields of hydrology and ecology, helping to provide the experimental foundations for the field of hydro-ecology. From 2005 to 2007 he chaired the innovative hydrological research programme of IAHS: Prediction in Ungauged Basins (PUB) which he advanced from a theoretical concept into different research directions where practical approaches to deal with prediction in data-scarce environments are developed. Jeff McDonnell is not only a world-wide leading and very well respected hydrologist, also his personality is absolutely engaging. He has an unlimited supply of energy and enthusiasm for the science of hydrology and related environmental issues. He is in particular helpful and supportive to younger scientists and students. It has always been a pleasure to see how he helps numerous PhD students at EGU meetings through fruitful discussions on their projects, either in front of their posters or after their presentations.

Contributions to Watershed Hydrology

Isotope hydrology Jeff McDonnell’s work on isotope hydrology in the 1980s began to examine some of the assumptions in the use of stable isotope tracers in watershed hydrology. He was the first to recognize that the weighting of the rainfall input had a significant effect on the integrated streamflow signal at the catchment outlet. Since that time, Jeff has led a shift in the field that explores the spatial and temporal variability of the input concentrations in rainfall and spatial variability of soil and groundwater concentrations, to now use these patterns as part of the tracing process. Today, many of these techniques have become standard, with McDonnell’s 1991 paper in Water Resources Research being cited widely as a landmark paper. He is co-editor of the successful “Isotope Tracers in Catchment Hydrology”, published by Elsevier, now in its 3rd printing. The UN employs Jeff (and his book) as its main lecturer for short courses on Isotope Hydrology as part of the new Joint International Isotope Hydrology Program (JIIHP), and he has so far taught in China and South Africa.

Rainfall-runoff processes and modelling Jeff McDonnell has contributed greatly to the understanding of how rainfall and snowmelt are converted to runoff. His paper on hillslope and watershed scale runoff generation and resolution of the age, origin and pathways of storm runoff at the Maimai watershed in New Zealand is a classic, and used throughout the world as a standard reference. The pioneering insights he gained from the Maimai watershed and the resulting conceptual model of hillslope runoff dynamics, have now been confirmed in studies in Canada, Japan and the USA. Subsequent to this, Jeff is now leading a paradigm shift in the field, away from standard steady state variable source theory and models based upon it, to descriptions of watersheds as a series of cryptic reservoirs that are highly threshold dependent, and highly dynamic in terms of the hydrologic connectivity between the various components. Jeff McDonnell is working to bridge the experimentalist and modelling worlds by advocating the use of “soft data” for multi-criteria model calibration. This is a significant advance in terms of how the community might, at last, bring the often complex, yet qualitative realm of the experimentalist into model testing and calibration. In recent times he has introduced into the literature the idea of “virtual modelling experiments”, tools that promote dialogue between experimentalists and modellers, to formulate hypotheses that can then be tested through carefully constructed field experiments.

Hydrobiogeochemistry While nutrient flushing dynamics are often studied by biogeochemists and runoff dynamics by hydrologists, Jeff McDonnell has contributed many new ideas for linking the two fields. He has defined new conceptualizations of how hillslopes and riparian zones connect and disconnect in time and space, and how this phenomenon controls watershed nitrification and denitrification. He was the co-convener of the US-Japan Workshop on Forest Hydrology and Biogeochemistry that brought together leading scientists from Japan and USA. The proceedings of the meeting is now standard reference for defining how hydrology and biogeochemistry are linked at the watershed scale.

International Impact and Scientific Recognition

Publication Record Jeff McDonnell has an outstanding publication record: 81 articles in the top international journals, 6 edited books, 11 book chapters, and numerous papers in refereed conference proceedings. He has an H-index of 21. Leadership and Recognition Jeff McDonnell is a truly international scientist. Jeff McDonnell has studied in Canada and New Zealand, and held his teaching appointments in the USA. He has been a Visiting Professor at Bristol University, Freiburg University, the Japan Forest Products and Forest Research Institute, the University of Western Australia, Delft University of Technology, NASA Marshall Space Flight Center and Landcare New Zealand. Recognition of his leadership role is evident in many areas – Jeff is a member and past Chair of the Surface Water Committee of the AGU. He was President of the International Commission on Tracers, one of seven commissions of the International Association of Hydrological Sciences (IAHS). He is was member of the Science Steering Group of the IAHS’s Predictions in Ungauged Basins (PUB) decadal initiative, and the chair of PUB for the 2005-2007 period. The high esteem in which he is held in the international arena is reflected by invitations for serving as associate editor in the most prestigious journals in the field, by invitations to deliver plenary and keynote addresses at international conferences, and by awards in different countries (which are listed in his brief CV). Among others, he is or has been an Associate Editor of Hydrology and Earth System Sciences (HESS), Water Resources Research, the Journal of Hydrology and Hydrological Processes, the Hydrological Sciences Journal, the Wiley Encyclopaedia of Hydrological Sciences, and the Journal of Hydrologic Engineering (ASCE).

Summary

Jeff McDonnell’s groundbreaking contributions to Experimental Hydrology, particularly in the areas of isotope hydrology and rainfall-runoff process understanding at the hillslope scale, have significantly advanced hydrologic science, providing a foundation for the emergence of new theories. His pioneering work in hydro-biogeochemistry has provided an essential bridge for linking water quantity and water quality research. Awarding the Dalton medal to him is a fitting way to recognize these substantial contributions.