Luna Leopold enjoyed making measurements. He once told me of how he quantified dew when he was chief meteorologist at the Pineapple Research Institute in Hawaii just after World War II: After he checked the institute’s rain gauge each morning, he counted the dew drops on his boots. Years later, Luna determined the best time to fish on the trout stream near his Wyoming house by making hourly counts of fish rising to the surface, often convincing visiting friends and students to collaborate on the tally.
These stories are illustrations of Luna’s natural inclination to gather data, driving what became his legacy: transforming his field of process geomorphology from primarily a descriptive to a quantitative science. That legacy earned him several prestigious honors throughout his life, including the National Medal of Science, awarded by President George H. W. Bush in 1991, and the Robert E. Horton Medal, AGU’s highest recognition in hydrology.
I was one of Luna’s graduate students in the 1970s when he taught at the University of California, Berkeley. His propensity for measurement seemed to spill over into his teaching style as well. Luna designed his fluvial geomorphology graduate seminar not only to engage students in scientific discussions but also to hone their skills in public speaking—counting the number of times we would say “umm” or other hesitating words during our talks and teaching us to pause instead. This was just one of many ways in which Luna went beyond teaching the technicalities of his field to pass along other bits of wisdom that he thought would help us to have successful careers.
Today, I’m a professor at the University of Maryland, where I’ve researched and taught hydrology and geomorphology for nearly 30 years. Luna died in 2006. As AGU celebrates its Centennial this year with a look back at the major influences of the Earth and space sciences, I offer this remembrance of Luna’s life and work that so greatly affected the fields of hydrology and geomorphology.
Engineering, Meteorology, and Geomorphology
Luna obtained his undergraduate degree in civil engineering in 1936 from the University of Wisconsin–Madison, where his father Aldo Leopold, an ecologist, conservationist, and pioneer in wildlife management, was on the faculty. Luna lived at home and walked home for lunch.
His degree completed, Luna headed to the Southwest, where he worked on sediment erosion problems with the Soil Conservation Service. During World War II, he served in the Army Weather Service and Air Force and also obtained a master’s degree in meteorology from the University of California, Los Angeles, in 1944. In 1950, he completed a Ph.D. in geology from Harvard University, advised by the geomorphologist Kirk Bryan, for which he wrote a dissertation on the erosion problems in the Southwest that was also informed by his previous research and studies.
During this period, 61-year-old Aldo Leopold suddenly died from a heart attack in 1948. He had been working on a collection of essays that had been accepted for publication as a book shortly before his death. Luna took over manuscript preparation, and A Sand County Almanac, published in 1949, brought Aldo Leopold worldwide fame for his land ethic philosophy [Leopold, 1949].
At Harvard, Luna’s geomorphology studies reinforced lessons he had learned from his father about making careful observations and formulating questions. His doctoral training taught him how to discuss the scientific literature and present his work. His interest in research on rivers led him to join the U.S. Geological Survey (USGS) in Washington, D.C., in 1950. There he went on to develop a significant career, serving for a decade as the agency’s chief hydrologist.
Hydraulic Geometry of Rivers
The research that Luna conducted at the USGS forms the core of his contribution to geomorphology. Luna was interested in how rivers form stable channels, why channel banks are able to contain only small-magnitude floods, how channels transport water and sediment, and why rivers meander or braid.
He explored what he called the “hydraulic geometry of rivers,” inspired by research in India on irrigation canals by Gerald Lacey, an eminent British civil engineer. Lacey wanted to know how canals lined with sand could be stable. Indian engineers measured the hydraulic characteristics of stable canals, and Lacey refined his ideas and developed equations based on those measurements [Lacey, 1930, 1939].
Luna applied this data-driven, empirical approach to the study of natural river channels. What’s more, he used the USGS’s stream measurement database in a “data science” approach to the problem (although he used graph paper and a slide rule rather than high-speed computers). This work launched the transformation of fluvial geomorphology into a quantitative science.
Luna coauthored several landmark papers on the hydraulic geometry of rivers. In 1953, he and USGS colleague Thomas Maddock Jr. demonstrated that rivers undergo systematic at-a-station and downstream increases in width, depth, and velocity to accommodate increases in discharge [Leopold and Maddock, 1953].
Luna and his then USGS colleague and friend M. Gordon “Reds” Wolman did novel field studies to examine flow resistance and channel patterns in natural rivers [Leopold and Wolman, 1957]. Their work indicated that natural channels with riffle-pool sequences and river meanders had more resistance to flow than straight laboratory channels.
Robert M. Myrick, also of the USGS, and Luna collected field data to apply the hydraulic geometry approach to the study of tidal channels [Myrick and Leopold, 1963]. USGS colleague Walter Langbein then used their data to explain up-marsh decreases in width common to tidal channels [Langbein, 1963]. Luna, Wolman, and John Miller of Harvard University published their innovative research on rivers in a book entitled Fluvial Processes in Geomorphology [Leopold et al., 1964].
Akin to what happened with Luna’s father, Miller died before the book could be published, succumbing to bubonic plague he contracted during field work in New Mexico. While mourning the death of Miller, who was one of his best friends, Luna worked with Reds to complete this classic contribution to science.
Luna’s ability to put complex ideas into words was another skill that he learned from his father. Luna published papers throughout his adult life. As someone who wrote well and took pride in it, he considered writing a career that he could “fall back on.”
Taking the Academic Route
In the early 1970s Luna left the USGS to become a professor at the University of California (UC), Berkeley, where his brother Starker, a wildlife ecologist, was also on the faculty. Luna continued to work with colleagues at the USGS in a study of movement of sand along the bed of the East Fork River in Wyoming.
At Berkeley, he had appointments in geology and in the environmental planning department, where he developed the popular course “Hydrology for Planners” that examined the effects of urbanization on rivers and other problems. Partly on the basis of this course, Luna cowrote another important book, Water in Environmental Planning, with Tom Dunne, an innovative hydrologist and then a young professor at the University of Washington in Seattle [Dunne and Leopold, 1978].
I think Luna enjoyed some aspects of academic life, but the transition from the USGS to academia was not an easy one, particularly at that time. In the 1970s, the National Science Foundation did not have funding programs for hydrology or geomorphology.
Luna also struggled somewhat with the mentoring of graduate students. He enjoyed scientific discussions and gave us some good advice. For example, he encouraged us to give annual talks at national meetings, to ask questions, and to get engaged with scientific societies. He suggested that we work on three types of research projects at the same time: an important scientific project, a practical or applied project, and a project of personal interest that was inexpensive and close to home.
Luna enjoyed music (especially around a campfire) and brought it into scientific gatherings. His fluvial geomorphology seminar, for instance, which he held in his home, ended with a musical get-together to which students were encouraged to bring a friend and musical instruments.
During one field season, I stopped at Luna’s Wyoming house with my temporary assistant (and later husband), Jim Luhr. Jim was an excellent fiddler. Luna enjoyed playing along with his guitar and teaching us new tunes. He taught us the Mexican folk tune “Jesusita,” which we often played while doing field work in Mexico or waiting to get through customs at the border. Luna himself wrote, played, and published a song (“Better Get the Garbage Before It Gets You”) as part of a 1972 address that he gave when he retired as president of the Geological Society of America [Leopold, 1973].
On Women in Science
In the 1970s, I and many other women entered scientific graduate programs, so it was a time that tested people’s ability to adapt to changing social norms. Luna embraced the idea of increasing workforce diversity in science and took deliberate steps to further the inclusion of women. I remember him writing letters to nominate women to the National Academy of Sciences (Luna, his brother Starker, and his sister Estella were all members). However, he was less aware of the consequences of small decisions that affected the progress of women scientists and made their careers more difficult to accomplish.
For example, another lesson in public speaking from Luna’s fluvial geomorphology seminar was to carefully assess the audience and adjust the content to fit them. In particular, he suggested that we decrease the scientific content of our talks if there were many women in the audience. This struck me as wrong at the time, given that increasingly, women would be attending talks as scientists rather than the wives of scientists. During a refreshment break, I suggested this to Luna, which Luna’s wife, Barbara, gleefully remembered as the time I backed Luna into the refrigerator to discuss the issue. Luna didn’t use this example again.
Another time, Luna recommended a male undergraduate student instead of me for a USGS summer job that entailed working on rivers out of canoes. Not only did I, as a graduate student, have more training, but I had also been a long-distance canoe racer in high school. When I asked Luna about his choice, he said that he wasn’t thinking about our relative levels of experience; he was concerned with who would fit in with the USGS field crew (actually, my canoe experience might have made me a better fit). These a priori decisions are still common in academia and in the workplace. Even folks who encourage the diversification of the scientific workforce can be unaware of how such ideas as “apparent fit” help keep roadblocks in place.
Luna Leopold has long had an influence on me, starting well before I met the man. Like him, I grew up in Madison, Wis., where I read A Sand County Almanac in high school. I did my undergraduate studies at the University of Wisconsin and spent my free time on rivers and lakes. I worked the night desk at the geology library, where I discovered Luna’s 1964 book on geomorphology. After reading it, I decided to apply to UC Berkeley to study rivers.
Although more than a decade has passed since Luna’s death, he remains very much a presence in hydrology and geomorphology. Luna’s major books remain in print. They, along with his research papers, continue to inspire new ideas and new scientists. AGU keeps his memory alive by giving the annual Luna B. Leopold Young Scientist Award to an early-career scientist who advances the field of Earth and planetary surface processes. During a year in which we’re celebrating the last century of scientific advances, Luna Leopold deserves a place in the conversation not just for what he contributed then, but for the inspiration he will continue to give scientists in the field tomorrow.