M. Gordon Wolman

2000 Robert E. Horton Medal Winner

Johns Hopkins University, Baltimore, Md.

M. Gordon Wolman was awarded the Robert E. Horton Medal at the AGU Spring Meeting Honors Ceremony, which was held on June 2, 2000, in Washington, D.C. The medal recognizes outstanding contributions to the geophysical aspects of hydrology.


“Brilliant minds are not unusual among scientists. More uncommon are those who combine scientific acumen with a keen appreciation for history and geography, giving their work context in time and place. Rarest of all are those who can convey these gifts with humor, common sense, generosity, and style.

“Such a man is this year’s Horton Medalist, Professor M. Gordon Wolman, known far, wide, and hereafter as Reds. His career has left substantial legacies in hydrology and geomorphology as concepts, insights, publications, and, perhaps most important, students. He pioneered the first rigorous descriptions of natural streams and their beds and the first quantitative analysis of the relative effectiveness of geomorphic processes in shaping the landscape. He has given us new ways to think about the effects of land use, urbanization, and dams on channels and helped frame the international discussion on sustainable development.

“Reds comes by this medal honestly; his father, Abel, won it 14 years ago, making this the first father-son team to do so and adding the name of Wolman to other famous father-son teams: Bach, Einstein, and Ripken. Both father and son shared a fascination for water: clean in Abel’s case, dirty in Reds’. Reds began his career under the tutelage of some of this century’s greatest geomorphologists—Kirk Bryan, Luna Leopold, John Miller, and Walter Langbein, among others—and quickly became a part of what appears today as a golden age of fluvial geomorphology: the first attempt to rigorously and quantitatively describe the behavior of rivers.

“Singling out any particular work as Reds’ most influential is difficult. His 1953 paper on sampling particle size distribution of river beds led to the “Wolman pebble count” as a standard technique for geomorphology classes everywhere. His Brandywine Creek study is a classic example of a comprehensive geomorphic examination of a channel, presaging much of the contemporary interest in watershed analysis. His 1960 paper with John Miller and a follow-up in 1985 with Ran Gerson introduced the concept of evaluating geomorphic processes by integrating across the frequency distribution of effective events, providing much of the theoretical basis for modern process geomorphology. His 1967 paper on effects of urbanization on streams foreshadowed an entire subfield of hydrology. His 1978 paper with Gar Williams on downstream effects of dams is the standard reference for a global technical and policy debate. His papers in the last two decades span a wide range: fish spawning gravels, solid waste management, mountain stream organization, national water-quality trends, the relation between public policy and science, and, most fancifully, the role of play in science.

“No contribution better illustrates both his prescience and style than the 1964 classic “Fluvial Processes in Geomorphology,” by Leopold, Wolman, and Miller. Although written more than 35 years ago, it remains one of the most cited works in geomorphology and was recently republished by Dover, not as a historical artifact but as required reading for the newest generations of fluvial geomorphologists. Brimming with clarity and literacy (what other geologic text quotes Gertrude Stein on Niagra Falls?), it models how a textbook can be both scientifically authoritative and a good bedtime read.

“Arguably his most enduring legacy may be the generations of students he has taught over the years at Johns Hopkins. During the 1995 AGU Symposium in his honor, he was presented with an academic “family tree” that included 47 children, 106 grandchildren, 17 great-grandchildren, and four great-great-grandchildren. This tree continues to grow and branch, distinguished not only by the prominence of some of its members but also for the almost universal high regard and affection in which they hold their academic patriarch.

“I could go on and on citing Reds’ leadership role in professional societies and committees, etc., but I can hear him saying, ‘Please don’t.’ In his modesty, Reds seems genuinely surprised by the improbable course his life has taken. On a recent field trip down the Yangtze River, as the boat entered Wu Gorge with shafts of late afternoon sunlight illuminating an ancient temple on the flanks of Goddess Peak, Reds was heard musing, to no one in particular, ‘All this from counting pebbles!’

“Our community is indeed fortunate to count Reds Wolman among its elder statesmen—the Year 2000 Horton Medal could not be in finer hands.”

—GORDON GRANT, U. S. Forest Service, Corvallis, Oreg.


“The present is a propitious moment for hydrology, perhaps: a rare conjunction of interest in both the science of water and the management of water. The appearance of the science advisor to the President in a keynote speech on water at this AGU meeting is perhaps a manifestation of this special moment.

“Ancient, and some modern, civilizations in arid regions recognize the unique role of water in society. Today, the context is global. Moreover, the significance of water is recognized at what are often viewed as dichotomous poles in hydrology, science, and management. In one guise, water is a driving force in the dynamics of the atmosphere, a vital element in the creation of climate and of climate change. The management of water, seen as an increasingly scarce resource in many parts of the world, demands an understanding of the science of hydrology as well as the values, institutions, and machinery of social action. Both sides, the science of water and the management of water, capture today’s headlines. I believe this is a unique conjunction. This conjunction, of course, may or may not be propitious for funding. But, if it is, or will be, there are a few things we might try to do. Despite this heady platform, I do not have the capacity to list a priority of needs in the field of hydrology. I state here some biases, a few things perhaps worth focusing upon and a condition worth avoiding.

“Continued emphasis on the hydrologic cycle and on the role of water in models of the general circulation of the atmosphere on the globe remains of fundamental importance. Within that broad framework, the dynamics of the exchange of moisture between the litho-biosphere and the atmosphere remains a special challenge. For many water policy and management decisions, the oft repeated plea that finer spatial resolution is needed also remains true.

“As the sophistication of modeling at all scales increases, from the globe to the urban watershed, it has become evident that continuous, long-term records are essential both to hydrologic science and to water management. The need for long-term records exists in the United States, and the paucity of data in much of the developing world makes planning and design of water management systems, including the allocation of scarce water, much more uncertain than it need be. Conceivably, statistical issues of stationarity or the distribution of extremes even with long records, in the absence of some geophysical explanations of the driving mechanisms, may only be resolved in operational terms as allowances for risk, but the nature of the record is vital to the notion of adaptive management. Geologic reconstructions along with observation are needed to construct such records.

“In a concomitant vein, statistics alone are insufficient to understand the behavior of watersheds. Careful studies of processes responsible for the formation and transformation of the hydrograph, old-fashioned field studies in the eyes of some, remain essential to understanding the hydrology and to confidently translating this understanding into useful application.

“Institutions designed to manage water resources both depend upon and influence the kinds of hydrologic information collected and the way in which it is used. In the United States and in most nations, the many agencies of government are the dominant participants. No agency exists today at the federal level charged with the responsibility of rationalizing the diverse criteria and objectives of the many federal agencies with responsibility for different but interrelated facets of water management. Some inquiry into these institutional relationships may be warranted.

“These suggestions may be sufficiently broad to satisfy anyone’s taste in hydrology. I do not mean them to be, but more detail would be too much and inappropriate here. (What is appropriate here? Clearly, I don’t know.)

“While these calls for action are muted, almost a half century of exposure to the hydrologic scene suggests two features of the necessary debate over priorities in inquiry and research are to be avoided. I’ll call them rank and exclusivity. Rank may take the form of assertions of the superiority of theory over observations, of models over data, or of science over application. In principle, the general over the particular may indeed be more desirable. The same cannot be said, for example, for erroneous generalization or poor models. And, vice versa, bad observations even in the rain are not inherently better than some models. Exclusivity can be rank taken to the limit. However, no implication of rank per se is required. Thus there are enough data, models are useless, or watersheds not regions are the proper units of study. As the Eagleson committee makes clear, hydrology is inseparable from a host of processes encompassing the biosphere and lithosphere and the varied realms of water. Given that complexity, first-rate work from a vast variety of avenues is demanded. Of course, the rhetoric of rank and exclusivity is not unique to our fraternity. But we are a relatively small band needing common ground to be most effective.

“My citationist has been most generous. To those distinguished friends mentioned in the citation and to many others in the field, I owe my very good fortune. I am honored beyond measure to receive the Horton Medal from the American Geophysical Union.”

—M. GORDON WOLMAN, Johns Hopkins University, Baltimore, Md.