Bagnold, Ralph A. (Ralph Alger), 1896-

Alternative names
Birth 1896-04-03
Death 1990-05-28

Biographical notes:

Ralph A. Bagnold is a British engineer, soldier, explorer and theoretical physicist who has published widely on sediment-transport physics.

Luna Bergere Leopold, former Chief Hydrologist of the U.S. Geographical Survey, is a professor of geology and geophysics at UC Berkeley. Chiefly interested in the hydrology of arid regions, rainfall characteristics and river morphology, erosion and sedimentation, Leopold is the author of numerous works in the field of hydrology.

From the description of Correspondence, 1956-1986, with Luna Bergere Leopold. (American Philosophical Society Library). WorldCat record id: 122624446

A hydrologist, geologist, engineer, meteorologist, conservationist, and environmental commentator, Luna Bergere Leopold (1915-2006) mastered profoundly important work on the human understanding of-and appreciation for-living rivers. Holding a philosophy that streams (geologists often refer to all natural waterways as streams) are orderly, integrated parts of geological and human landscapes alike, he inspired the modern field of empircally derived fluvial geomorphology, developing the theory of hydraulic geometry. Meticulous observations in the field revealed to him how the physical characteristics of streams constantly change, not only as the stream flows across the landscape but at the same locales over time, under natural and human-influenced conditions. He derived formulas for analyzing and explaining these changes. He discerned and demonstrated the interrelations of these processes, especially when aspects of human intervention interfered with natural events, which have become integral parts of urban planning around streamscapes. In this work Leopold showed that the past and future histories of streams at all scales can be interpreted and postulated through objective field measurements of valleys, the channel geometry of the flowing stream, and the physical processes working within the moving fluid.

Leopold’s life-long philosophical beliefs of nature and environment were inspired by his father, Aldo (1887-1948), a forester and one of the leaders of the wilderness/environmental movement of the 20th century. Indeed, the Aldo Leopold family as a whole embraced the ethos of understanding the world as a multifunctional system of physical and biological agents, man included. After his father’s sudden death, Luna, then a graduate student and working in Hawaii, oversaw the editing and publication of his father’s most memorable work, a collection of essays published as "A Sand County Almanac" (that had been accepted for publication under the less identifiable title, "Great Possessions"). But it was not the last of the elder Leopold’s influences on his son and the family interests.

Many have used the Aldo Leopold perspective of environment to single-sidedly support protection of living ecosystems from human-caused change. However, Luna Leopold’s decades of field studies revealed, at least in the case of rivers and streams, how multivariate mechanisms may be measured, how changes occur, and, in humanly practical terms, how urban planners can integrate such findings into programs that affect the environment. His was a disciplined, documented, and repeatable approach to examining problems that were recognized but not understood. Luna Leopold’s research focuses reveal not only the influence of his father’s environmental awareness and land ethic, but his own interdisciplinary education. He earned a B.S. in civil engineering from the University of Wisconsin at Madison (1936), an M.S. in physics and meteorology from the University of California at Los Angeles (1944), and a Ph.D. in geology from Harvard University (1950).

After receiving his bachelor’s engineering degree, Leopold worked in the U.S. Department of Agriculture’s Soil Conservation Service in New Mexico, 1937-1940, advancing from junior to associate engineer, and in 1941-1942 worked in the U.S. Engineers Office in Los Angeles. During World War II, he served in the U.S. Army Air Force's Weather Service, 1940-1946, advancng from Private to Captain. He returned to civilian life as an associate engineer in the U.S. Bureau of Reclamation in Washington, D.C., then moved to Hawaii as Chief Meteorologist of the Pineapple Research Institute, 1946-1950. He returned again to Washington and worked in the U.S. Geological Survey (USGS) as a hydraulic engineer, 1950-1956, finally settling into his watershed career. In 1956 he became the first Chief Hydrologist of the USGS, which position he held until 1966 when he became Senior Research Hydrologist. During his tenure in the USGS he transformed the Water Resources Division from a group of data-gatherers into an applied research arm of the USGS. In 1971 he retired from government service, which opened the way to a new career. He held a joint professorship in both the Department of Geology and Geophysics and the Department of Landscape Architecture in the University of California at Berkeley from 1973 until retiring (again) in 1986, when he was made Professor Emeritus. During his post-UCLA retirement years Leopold also worked as a consultant to local, state, and federal agencies and private organizations, including also serving as an expert witness in a federal trial that addressed effects of fluvial geomorphology.

During Leopold’s meteorologist years in Hawaii, he contributed to a corporate collection of environmental papers, "On the Rainfall of Hawaii". The theme of his paper therein, "Hawaiian Climate: Its Relation to Human and Plant Geography", unambiguously displays the quintessential Leopold, a past-to-future viewpoint that he garnered from his father and which he would apply to all of his later work, delving into the effects of the hydrologic regime on human affairs. During this time in Hawaii he participated in early experiments in cloud-seeding with dry ice as a means to promote rainfall. The photographs in his personal Journal (Series XII) from this time clearly demonstrate the meager results of a method that, once promised to be a marvel of the future, has fallen from scientific practicality.

At the outset of his career as a hydrologist, Leopold first tested the waters in a report that, as with his early field notebooks and his Hawaiian climate report, reflect the Aldo Leopold legacy of environmental change and his own proclivities for climatology, hydrology, and geomorphology. He wrote "Vegetation of Southwestern Watersheds in the Nineteenth Century" ("Geographical Review", 1951) as a revision of his doctoral dissertation from Harvard, which is still a classic work on the subject of climate change and effects on land use particularly as the result of livestock grazing in the late 1800s. He empirically debunked some long-held traditions that the American Southwest had been tall with grasses during the time of pioneer incursions, while taking note of the real strain of grazing on limited resources.

Leopold coursed the way for future generations of hydrologists and land planners in a 1953 USGS Professional Paper, "The Hydraulic Geometry of Stream Channels". His meticulous field work, done both as pure research and in response to urban planners' need for practical applications, culminated in the 1964 publication of the benchmark text, "Fluvial Processes in Geomorphology" with M. Gordon Wolman and John Miller (W.H. Freeman, 1964), a title still available in reprinted form. Other important, theoretical works include two USGS titles coauthored with hydrologist Walter B. Langbein, "River Meanders: Theory of Minimum Variance" (1966) and "River Channel Bars and Dunes: Theory of Kinematic Waves" (1968). Their theoretical work was the product of the years when Leopold and Langbein established a national program of water resources research within the USGS.

Leopold's early studies of the behavior of flowing waters, and his methods, were the bellwether and benchmark for the field of environmental hydrogeology and the special discipline of social geomorphology. Most of his field studies dealt with smaller living streams, especially intermittent arroyos and ephemeral streams in the American West and Northeast, and, more theoretically, the formational and sedimentary principles in the development of stream meanders. His selection of field areas was neither random nor so much administratively imposed, but the direct reflection of his tendency to also persue his hydrological studies as a matter of avocation in the areas where he lived; first in the environs of Washington, D.C., then in California and Wyoming. One of his most classic study sites, which he revisited for decades, was Watts Branch near Rockville, Maryland; the data acquired in field studies there figure prominently in his theoretical and applied work. Another prominent site, similarly well studied and applied, was the New Fork River near his summer cabin in Pinedale, Wyoming. Of course, Leopold's studies took him elsewhere as well in the course of his professional career under the oversight of administrators' agendas, such as another well-studied Leopold locality, the Arroyo de los Frijoles near Santa Fe, New Mexico. Data, maps, and research material pertaining to all of these localities (and numerous others) are represented throughout the Leopold Papers.

In 1965 chiefly, Leopold also pioneered the application of his methodologies to large canyonbound rivers in the American West; specifically, the Green River and San Juan River in Utah, and the Colorado River in Utah and Arizona including Cataract Canyon, Marble Canyon, and the Grand Canyon. In the Grand Canyon he was the first to demonstrate the geomorphic genesis and evolution of the rapids and pools that memorably characterize this reach of the Colorado River. These were his only excursions into detailed field work on large rivers, but they are every bit as significant to the studies of such streams as are his studies of more modest streamways, the small rivers, creeks and arroyos for which he became so well known.

Leopold acquired a private pilot's license and overflew some of his field areas (but not the canyonbound rivers), as documented in some photographs in the collection. He also took the opportunity to take landscape photographs during commercial flights both domestically and during his world travels. All told, however, his personally-taken aerial views, while they are useful, do not number many in this collection; yet they document his incessant studies of rivers and the land.

A sample of the approximately 200 of Leopold’s publications finds magisterial series of technical reports and scientific papers with detailed, informative titles; but his overarchingly comprehensive works on fluvial geomorphology have a propensity for deceptively simple titles, such as "Rivers" ("American Scientist", 1962), "Water" (Time, 1966), and "Water, Rivers and Creeks" (University Science Books, 1997). For those who may inquire of these subjects at a more introductory level, he wrote "Water: A Primer" (W.H. Freeman, 1974); or for those who seek something with immediacy in practical management applications, "Water in Environmental Planning" (W.H. Freeman, 1978), coauthored with Thomas Dunne, with whom he also devised a "Field Method for Hillslope Description" in 1971 (for the British Geomorphological Research Group). With coauthor Helene L. Baldwin, Leopold also wrote the young-reader title, "Water" (Saalfield Publishing, 1962). During 1990-1991, he was interviewed on tape by Ann Lage at the University of California at Berkeley; bound copies of the lengthy transcript were made available by UCLA's Department of Special Collections (a copy of which is present in this collection).

Leopold’s work ethos and temperament for social and physical environmental affairs did not constrain him to the defined channels of the fluvial streams he studied. Understanding that an ecosystem is a naturally defined product of many physical and biological systems, including anthrogenetic impacts, he also considered the environmental and social issues of estuarine landscapes, where water needs "to sit around for a while" rather than be shot to sea between levees, propelled by the weight of water behind dams (Opening Remarks in the State of the Estuary Conference, San Francisco, 1999). And as the village elder of world sociogeomorphology, Leopold served as a human conscience for rivers everywhere; see for example his benchmark review, "A View of the River" (Harvard University Press, 1994), "A Value in Fear: Some Rivers Remembered" ("International Journal of Wilderness", December 2000), and, with Reed Huppman and Andrew Miller, "Geomorphic Effects of Urbanization in Forty-one Years of Observation" ("Proceedings of the American Philosophical Society", September 2005). He also branched into archaeology with an important regional paper based on more of his opportunistic and avocational work in Pinedale, Wyoming, "Archaeological Trash: Geomorphology and Early Human Occupation in Wyoming", with coauthor Claudio Vita-Finzi ("Catena", 2005).

More than 70 field notebooks (Series XI) and more than a hundred original plane-table maps (Series XIX) comprise the most significant parts of the Leopold papers in this collection, spanning a remarkable seven-decade field career, 1937-2003. They are vivid testimony to the development of Leopold’s methods and ideologies.

Luna Leopold compiled a personal "Journal" (Series XII), heretofore unavailable to researchers, which may well be the most embracing picture of the man, his work, and thoughts. Eleven volumes, hand-bound by Leopold, and a twelfth volume in progress, tell his personal stories, work perspectives, and travelogues from 1931 to 2003, although the last two volumes of his "Field Notes" (Series XI) also served to document some of his personal activities and thoughts from 2001 to the day before his death in 2006. The Journals are profusely illustrated with photographs and some hand-drawn sketches; even the occasional water-color painting. Extensive handwritten and typewritten texts detail adventures, observations, concerns, and ideas. The earliest of Leopold's Journals delightfully record an observant naturalist’s eye, salting his pages with careful drawings of birds, and laying between the leaves of the book pressed plants and bird feathers. He dabbled in poetry, some of which appears in his Journals and Field Notes, as well as an unpublished small collection that he assembled in the 1990s. His Journals and Field Notes also contain diversions of musical lyrics (some of them original) and musical notations, usually for guitar.

The Field Notes range from casual observations, through the gamut of meticulous pages of field measurements and readings, to postulations of cause and effect among substrates, vectors, and volumes. Hardly restricted to dreary, clinical recitations, he reports on other matters; for example, without undue dismay the malfunction of all(!) of his fathometers on the first day of an important trip in 1963 through Cataract Canyon, Utah, soon to be flooded in its lower end by the Colorado River pooling behind Glen Canyon Dam (closed 1963). As a wandering minstrel, he breaks into long verse and tippler's humor during the seminal hydrological field trip in Grand Canyon, 1964.

The plane-table maps (Series XIX) contained in the collection are geological art compiled by Leopold and field companions and students in the team he named the "River Boys" (the field long was traditionally the realm of men, although no longer so by the time of Leopold's formal retirement). The maps not only graphically preserve the detailed measurements of the day on numerous creeks and rivers across the United States, but they record a deft hand at the alidade, using hand-driven methods with no more than a keen eye, sharp pencil, arithmetic tables, and at least one dedicated rodman moving about in the distance-or in another instance documented by a pencilled sketch, a rodman holding the tall stadia rod vertically in a canoe. In the Grand Canyon, he plotted the flowlines of whitewater rapids by using the expedition's rafts as floats, tracking them with rapid-fire plane-table measurements from shore while they ran the rapids, communicating with the boats by walkie-talkie. An artistic hand brings form rather than rude interface to stream edges, delineated by constellations of rod points and elevations. Less precise or mechanical by today’s standards of laser-ranging devices, GPS receivers, radios, and digital tablets, the Leopold maps are the original field records for important hydrogeological principles then under development, which today are the core subject of coursework in hydrology classrooms and laboratories. The maps also are in some cases the earliest known records of the hydrological and geomorphological characteristics of many stream courses, which since have been greatly altered, anew or continuously, by human activities. And in some cases, Leopold has doodled sketches on the maps, artfully depicting field equipment or observations; for example, an owl and a dutch oven.

Luna Leopold served on the Boards of Directors of the Aldo Leopold Foundation, a conservational organization established by the Leopold family, and of the Sierra Club during 1968-1971. He also had been on the Board of Trustees of the National Heritage Institute, a not-for-profit organization of conservation lawyers and scientists providing programs, legal services, and consulting on matters of social and economic importance to the environment. And his environmental interests and their application to human problems in the landscape did not diminish with passing time. Among other subjects, he wrote a cautionary 1996 report on "Sediment Problems at Three Gorges Dam", the controversial, massive dam then planned for the Yangtze River of China that went on to profoundly affect environment, cultural history, and human lives alike. He was on the Scientific Advisory Board of the Center for Conservation Biology. In 1997-1998 he was the President of the Pacific Division of the American Association for the Advancement of Science.

Series II in the Luna Leopold Papers comprises the 1956-1988 correspondence of RALPH ALGER BAGNOLD (1896-1990). Leopold first discovered Bagnold’s work in a second-hand book shop. An inquiry to the author led to a vigorously productive and collegial three-decade relationship between them. Bagnold's hydrological theories were field-tested by Leopold and others in the U.S. Geological Survey, which contributed to significant advances in the field and brought international recognition to Bagnold among his geological peers.

Bagnold was a kindred multidisciplinarian-soldier, explorer, engineer, theoretical hydrologist, and sedimentologist. His education was at Malvern College, the Royal Military Academy (Woolwich), and Gonville and Cayus College, Cambridge University. He was commissioned a Second Lieutennant in the Royal Engineers in 1915 and served in the trenches of France and Flanders during World War I. After the war, he was stationed in Egypt, India, and China. During his duties in Egypt in 1925, he became interested in the geomorphology of sand dunes and became an astonishingly accomplished desert explorer in North Africa, crossing the Sahara several times and enjoining similar explorations elsewhere including the Empty Quarter of the Arabian Peninsula. For his first published work, "Libyan Sands, Travel in a Dead World" (London, 1935), he received the Founders Medal of the Royal Geographical Society. He was recalled to active military service in 1939, stationed in East Africa with the Seventh Armoured Division where he formed the Long Range Desert Group, or "Desert Rats", contributing considerable field experience in military desert travel. He attained the rank of Brigadier, and in 1941 he was honored with the Order of the British Empire (O.B.E.). In 1944 he was elected a Fellow of the Royal Society. Shortly thereafter he retired from military service, after which he became Director of Research for the Shell Oil Co. He enthusiastically pursued research on the problems of shock waves and their effects on sea walls, and studied the movement of stream sediments and the movement of particles in water and air both. It was in this last field of study that he his best known as a theoretician, having forcibly removed the science of subaerial particle movement from the traditional kinematic views held by engineers.

Bagnold was the first recipient of the G.K. Warren Prize of the (U.S.) National Academy of Sciences in 1969. In 1970, he received the Penrose Medal from the Geological Society of America. He was a Fellow of the Imperial College, University of London, and in 1971 received the Wollaston Medal, Geological Society of London. In 1974 he was elected a Foreign Honorary Member of the American Academy of Arts and Sciences. The International Association of Sedimentologists presented him the Sorby Medal in 1978; and he was given the David Linton Award by the British Geomorphological Research Group in 1981. He was awarded honorary D.Sc. degrees from the University of East Anglia and from the Danish University of Aarhus. His memoirs were published in "Sand, Wind and War" (University of Arizona Press, 1991). Other papers and correspondence of R.A. Bagnold are in the Churchill Archives Centre, Cambridge (U.K.), there comprising 12 boxes and a plan chest. [N.B.: Leopold's outgoing correspondence to Bagnold was written in longhand with no copies retained; Bagnold had not kept the correspondence he received from Leopold (fide Luna B. Leopold to "Kevin" [Thomas Kevin Cherry, Mellon Library Intern, APS], 1991, correspondence in APS Manuscripts Dept. Legal File for Leopold).]

The Bagnold family, including his wife, Penelope, formed a close relationship with the Leopold family, which is also represented in the general correspondence in this collection.

LUNA B. LEOPOLD was elected to APS membership in 1972. Among numerous other awards and honors he was the recipient of the Kirk Bryan Award of the Geological Society of America (1958); Distinguished Service Medal, U.S. Department of the Interior (1958); Veth Medal, Royal Netherlands Geographical Society (1963); medalist of the University of Liege, Belgium (1966); Cullum Medal, American Geographical Society (1968); Member, (U.S.) National Academy of Sciences (1968); Distinguished Service Citation, University of Wisconsin (1969); Fellow, American Academy of Arts and Sciences (1969); Rockefeller Public Service Award (1972); Warren Prize, National Academy of Sciences (1973); "Rivers 1976" award, American Society of Civil Engineers; Fellow, California Academy of Sciences (1982); Forchheimer Foundation Senior Fellow, Hebrew University, Jerusalem (1983); Busk Medal, Royal Geographical Society (1983); Berkeley Citation, University of California (1986); David Linton Award, British Geomorphological Research Group (1986); Linsley Award, American Institute of Hydrology (1988, 1990); Henry P. Caulfield, Jr., Medal, American Water Resources Association (1991); Distinguished Career Award, Quaternary Geology and Geomorphology Division, Geological Society of America (1991); (U.S.) National Medal of Science (1991); Palladium Medal, National Audubon Socity and American Association of Engineering Societies (1991); Robert E. Horton Medal, American Geophysical Union (1993); Penrose Medal, Geological Society of America (1994); Ian Campbell Medal, American Geological Institute (2000); and, posthumously (only by his death a few months before the award ceremonies), the Benjamin Franklin Medal in Earth and Environmental Science from The Franklin Institute in Philadelphia, 2006, which was accepted by his brother, Carl.

He also received honorary degrees from several schools: D.Geogr., University of Ottawa (1970); and D.Sc. degrees from Iowa Wesleyan University (1972), University of Wisconsin at Madison (1980), St. Andrews University, Scotland (1981), and University of Murcia, Spain (1988).

Luna Leopold was born 8 October 1915 in Albuquerque, New Mexico. Through his mother, Estella Bergère, he was descended from the Luna family, one of the pioneer Spanish families of New Mexico.

Leopold was first married to Caroline, with whom he had two children. The marriage ended in divorce. He married in 1973 Barbara Baker Beck, widow of Leverett Nelson. Leopold's professional and private lives were always inseparable, but even more pronounced during his working-retirement years. This is revealed by the content of his correspondence, of course, but most notably testified to by the fact that many of the salutations, even those that are professional in nature, are addressed to both "Luna and Barbara". The Leopolds opened their home in Berkeley, California, and their summer cabin in Pinedale, Wyoming, to a constant flow of guests; some were hunting and fishing friends, while many others were traveling and vacationing professionals engaged with Leopold in his avocational studies of streams near his "backyards" or who paid courtesy calls on the Leopolds. Even correspondence between members of the Leopold family (his siblings and his children) meanders from personal commentaries to discussions of various family not-for-profit foundations, professional affiliations, and business affairs.

He died 23 February 2006 in Berkeley, California. Five days earlier, he had written in his notebook, "I want to start a new book but the energy is lacking . . . ." His last notations also record that he had also been hard at work finalizing preparations for the "Leopold Conference" commemorating the environmental philosophies of his father, Aldo. His long-time colleague, coauthor and friend, Claudio Vita-Finzi of The Natural History Museum, London, was his memorialist for the Geological Society of America and the American Philosophical Society. An obituary appeared in newspapers across the country, including "The New York Times" and "The Washington Post". He was survived by his first wife, Carolyn Michaels; his children, Bruce and Madelyn, and step-children T. Leverett "Rett" Nelson and Carolyn T. "Carrie" Nelson; and three siblings, Nina Leopold Bradley, A. Carl Leopold, and Estella B. Leopold (APS 2000). His brother, A. Starker Leopold, and his second wife, Barbara, predeceased him in 1983 and 2004, respectively.

From the guide to the Luna Bergere Leopold Papers, circa 1909-2006, bulk 1931-2006, (American Philosophical Society)


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  • Sedimentology
  • River sediments
  • Hydrology
  • Sediment transport
  • Geology
  • Geomorphology--Fluvial


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