It is indeed a great honor for me, and also a great pleasure, to present to you the 1988 recipient of the Robert E. Horton Medal, Peter S. Eagleson. Shortly after it became public that Pete was the winner of this year's medal, I commented to my wife that, although I had never given a citation for an AGU medalist, this was one I would really love to give. The reason is simple: there is no one in the world who better represents the standards of excellence that a hydrologist hopes to achieve and that hydrologists hope our discipline will attain than Peter Eagleson.
Pete did not start his research career in hydrology. In fact, his Ph.D. thesis in 1956 and his research up to 1965 were mainly in the field of sediment sorting and transport by waves on beaches. During this period he also investigated problems related to flow-induced vibrations of plates. His research in these areas was extremely successful, producing three chapters in books and about 20 journal papers in addition to many technical reports and journal discussions. Indeed, Pete had made his mark in wave theory and sediment transport, but it was good fortune for our field that starting about 1964 his interest in hydrology overcame all his past experience and assured a reputation in the waves and sediment field, and thus he embarked on a new adventure—bringing into hydrology the scientific rigor that existed in more academically established disciplines. With his strong fluid mechanics background—he still teaches that subject to undergraduates at MIT—Pete was ideally suited to lead the field toward new problems and also toward new approaches to old problems . . . and this he did indeed! Just in 1967 he and his students published six papers, most of them in Water Resources Research, which had a strong, an almost immediate impact on the field of hydrology. Here was somebody who was tackling the modeling of overland flow with the scientific standards of fluid mechanics. At the same time, finally somebody had arrived in the field who, using techniques from signal analysis, produced criteria for the optimum density of rainfall networks. I did not know Pete at that moment, but I remember reading many times his paper on the optimum density of rainfall networks and feeling the excitement of the author's original mind at work. It is the same feeling one has when reading his 1972 classic paper on the dynamics of flood frequency, where for the first time the stochastic nature of flood is analytically tied to the physical-dynamic characteristics of the basin response. This intimate linkage between the probabilistic aspects of the phenomena, so crucial to hydrology, and the dynamic modeling of the physical aspects of the processes has become the trademark of Peter Eagleson's research and has had a profound influence in the field. Probably nowhere is this mark more evident than in Eagleson's series of seven papers, “Climate, Soil and the Water Balance: A Framework for Their Analytical Coupling,” published in 1978 in Water Resources Research. These papers are a magnificent display of imagination and analytic strength which go directly to the heart of hydrology, culminating with the dynamics of the annual water balance of the basin scale. They constitute a standard reference in the field and in my opinion one of the most significant hydrologic contributions in the last 20 years. This research led to Eagleson's theory of ecological optimality in water-limited soil-vegetation systems and inspired follow-up research in different parts of the world on this most important topic.