It is a pleasure to write this citation for Dr. Hongbo Ma, recipient of the 2023 Luna P. Leopold Award. In the 9 years since Hongbo completed his Ph.D., he has accomplished more to advance the field of sediment transport theory than was achieved in perhaps the previous 35 years. In a series of three papers published between 2017 and 2022, Hongbo provided novel theoretical insight into nonlinear transport phenomena by combining detailed field measurements with laboratory flume data, so advancing our physical understanding of the linkages between grain size, shear stress, and sediment flux.
Moreover, Hongbo has demonstrated an extraordinary application of his work to society, including the novel finding that channel bed degradation downstream of dams can lead to enhanced flooding risk. This is one of the more startling and counterintuitive ideas presented to date in the discipline of fluvial morphodynamic research.
Hongbo enthusiastically led extensive field studies of the Yellow River (in China), with one of his first findings showing, through direct measurements, that the bed features dunes that possessed abnormally large length-to-height ratios. With this observation, Hongbo demonstrated that the exceptionally high sediment flux of the very fine grained Yellow River is in part a consequence of enhanced efficiency of boundary shear stress; specifically, that low-relief dunes significantly reduce form drag and render nearly all boundary shear stress available for sediment transport. Hongbo then retooled a timeless sediment transport equation (Engelund-Hansen) to account for low-relief dunes and produced a new physically based sediment transport relation, validated with field data. The breakthrough from this research is a formula grounded in physics that is transferable to other fine- grained systems.
The Leopold Award is named in honor of a scientist “who engaged with and nurtured early-career scientist throughout his distinguished career in hydrology and fluvial geomorphology.” Hongbo reflects these virtues, as he excels in mentoring and drives civic engagement. He is a natural and gifted educator, and an effective communicator who actively seeks student involvement. His patience is bottomless, and he deeply cares about helping students acquire an intuitive understanding of natural systems.
Hongbo completed his Ph.D. in 2014 at Tsinghua University in China. He then went on to several postdoctoral research positions in the United States before returning to take the position of assistant professor at Tsinghua University in 2022. His enthusiastic cooperation with researchers both in China and around the world has helped our field grow in a substantial way.
—Gary Parker, University of Illinois Urbana-Champaign
Delta shoreline structure has long been hypothesized to encode information on the relative influence of fluvial, wave, and tidal processes on delta...