Wilfried H. Brutsaert

1999 Robert E. Horton Medal Winner

Cornell University, Ithaca, N.Y.

Wilfried H. Brutsaert was awarded the 1999 Horton Medal at the AGU Fall Meeting Honors Ceremony, which was held on December 15, 1999, in San Francisco, California. The Horton Medal is given for outstanding contributions to geophysical aspects of hydrology.


“The Horton Medal is for ‘outstanding contributions to geophysical aspects of hydrology.’ By any measure chosen, Wilf Brutsaert is most deserving of this honor.

“I first met Wilf in 1981 when we worked together on the editorial board of Water Resources Research. I quickly came to value his wise counsel and friendship and the depth and breadth of his scholarship. He is extremely generous with his time for family, friends, students, and colleagues. He provides intellectual leadership to the community through his personal scholarship and collaborations. He brings the enthusiasm of the brightest and most energetic, recently graduated Ph.D. to all that he does. His decades of leadership within AGU and in numerous activities that have yielded scientific opportunities for many have been absolutely selfless.

“Wilf has investigated primarily the fluid mechanics of environmental phenomena to solve critical problems of hydrology. His research constitutes a perfect balance of theory with careful and appropriate experiments. He has published pioneering and lasting papers on vadose-zone and hillslope hydrology, gas exchange at air-water interfaces, and aquifer dynamics. He is best known, however, for his original and incisive contributions in the description of the transport of vapor through the Earth-atmosphere boundary layer and has been at the forefront of establishing programs that make the best use of both groundbased and remote platform measurements to quantify evapotranspiration. As an example of his influence, authors now refer to one of his similarity schemes as the ‘Penman-Brutsaert’ approach.

“Wilf writes beautifully, never overstating the case, and always places the situation into perspective. There are several examples that highlight the breadth and depth of his work on evapotranspiration. His 1976 paper with Mawdsley, The application of planetary boundary layer theory to calculate regional evaporation, revolutionized the use of atmospheric boundary layer fluid mechanics to estimate regional evapotranspiration. His 1986 paper, Catchment scale evaporation and the atmospheric boundary layer, provided the foundation for the direction of significant ongoing research by many colleagues. The 1992 paper with Sugita, Landsat surface temperatures and radiosoundings to obtain regional surface fluxes, and the 1996 paper written with Qualls, Evaluation of spatially distributed ground-based and remotely sensed data to estimate spatially distributed sensible heat fluxes, demonstrate his penchant for tackling ‘wicked,’ real-world problems. His 1998 Nature paper with Marc Parlange on the Evaporation Paradox resolves a thorny problem in hydrology and a key issue in the current global change debate.

“Wilf cares deeply about and makes the considerable effort to research the history of our field. An example is from his 1992 AMS Horton Lecture, Horton, pipe hydraulics and the atmospheric boundary layer (Bulletin of the American Meteorological Society, June 1993) in which he traced the theoretical developments of the atmospheric boundary layer methods used to estimate vapor transport from large land areas. He identified the critical measurements supporting the early theoretical developments of Blasius and Prandtl as those conducted in 1902-1903 at the Hydraulics Laboratory at Cornell University, Wilf’s academic home, to determine resistance to water flow in pipes. (Robert Horton worked with the research staff, Saph and Schoder, soon after they completed this work.) Before Wilf’s lecture, few knew about the early fundamental measurements underpinning this theory.

“Marc Parlange summed up Wilf’s work: ‘He has done it all in hydrology. He has carried out brilliant research in numerical and analytical methods for partial differential equations describing environmental transport, he has collected precious laboratory and field measurements which remain benchmarks for theoretical comparisons, and he has developed foundational theories for the description of regional hydrology and land-atmosphere vapor exchange. No physical hydrologist has ever touched so many areas in such depth.’ Kuo-Nan Liou commented that Wilf’s 1982 book on evaporation into the atmosphere ‘has been and is still considered by many scientists in atmospheric and hydrological disciplines to have provided the physical foundation for the connection of the land surface and atmospheric boundary layer.’ Jeff Dozier observed that this ‘is the best reference book on my shelf.’

“Wilf Brutsaert embodies all that is good about AGU, is the complete academic scholar-teacher and research scientific leader, and exemplifies ‘unselfish cooperation in research.’ President Knauss, ladies and gentlemen, it is a privilege and honor to present my friend and colleague, the winner of the 1999 Horton Medal, Wilfried Brutsaert.”

—STEVEN J. BURGES, University of Washington, Seattle


“Thank you, Steve, for your generous citation.

“Mr. President, ladies, and gentlemen, despite what Steve Burges has just been trying to tell you, the reality is that I have somehow had the good fortunes of being at the right place at the right time and of meeting the right people at different junctures in my life.

“Certainly, it was nothing but a coincidence and mostly sheer luck that when I arrived on a freighter and first set foot on this continent as a fresh graduate to hitchhike my way from New York to California, Sputnik had just been launched. This event, in the middle of the Cold War, would eventually lead to what was probably one of the largest expansions and hiring sprees in the history of higher education in this country. Of course, I had no way of knowing then that I would end up in a life of research and teaching and that it would eventually come to this.

“I was also unbelievably fortunate in being able to interact with several outstanding individuals, and there is no question that whatever this medal holds or reflects, the merits are as much theirs as they are mine. As early as my undergraduate years in Ghent, it was a stroke of good luck that I was exposed to the mathematical discipline of Gerard Heyndrickx and to the straightforward charisma of Don Kirkham, which made me decide to go on to graduate school. It was Kirkham who then steered me to one of his former graduate students, Jim Luthin, at the University of California at Davis, which at that time was one of only a handful of institutions where hydrology was being approached in a comprehensive and fundamental way. At Davis, Don Nielsen’s analytical and experimental insights exerted a lasting influence on my thinking. And after I came to Cornell, my almost daily interactions with Jim Liggett, Gerhard Jirka, and, more recently, Jean-Yves Parlange were invaluable and stimulating. Among the other colleagues who were a source of inspiration and motivation over the years, I have to mention Giichi Yamamoto at Tohoku-Dai in Sendai, Dirk Kraijenhoff van de Leur at Wageningen, Herbert Lang at the ETH in Zurich, Peter Eagleson at MIT, Francois De Troch at Ghent, and Kuo-Nan Liou at UCLA. In addition, over the years I have been blessed by a steady stream of graduate students. They are too numerous for me to thank them by name here and now, but they know who they are. Let me just say that to work with them has been one of my life’s greatest pleasures. Finally, I would have liked to recognize my wife, Toyo, my close companion and friend for the past three decades. But I know she doesn’t want me to talk about that….

“In closing, I want to express my gratitude to AGU for bringing us all together here in this spirit of fellowship and cooperation and to the members of the Horton Medal Committee for their trust and confidence.”

—WILFRIED H. BRUTSAERT, Cornell University, Ithaca, N.Y.