James Kirchner

The 2013 Ralph Alger Bagnold Medal is awarded to James Kirchner for his outstanding contributions to our understanding of geomorphological processes using innovation and rigor in data analysis and slicing through the complexity of Earth’s surface systems to uncover the underlying physics.

James Kirchner carried outstanding research in geomorphology for over two decades. Kirchner’s work is summarised in over 100 peer-reviewed publications spanning a broad range of topics in the field of geomorphology and the allied disciplines of hydrology, geochemistry and ecology. These publications have had a profound impact, with some 4,000 citations to date reflecting community-wide appreciation of research that has been both substantive and timely. His research is a consistent blend of innovation and rigor in his approach to data analysis; this has repeatedly helped pave the way for fresh, quantitative understanding of processes ranging from erosion in steep catchments to the resistance of lowland floodplains to meander migration. Further, Kirchner has an acute ability for slicing through complexity in Earth surface systems to emerge with simple answers reflecting underlying physics that enrich understanding of surface processes.

Kirchener’s innovative approach to geomorphology is reflected in his research. Early in his career, he used simple yet innovative statistical tests to show that regular patterns in drainage networks (reflected in Horton ratios) are not reliable indicators of either randomness or geomorphic process, as decades of studies on the topic and dozens of textbooks had suggested. More recently, Kirchner used his statistical insight to help solve other puzzles about regularity in landscapes. Two such cases include explaining the formation of evenly spaced valleys, and parameterising hillslope sediment transport processes in terms of nonlinear diffusion. Early in the cosmogenic revolution in geomorphology, Kirchner had the crucial insight that cosmogenic nuclides in stream sediment should reflect catchment-averaged erosion rates; he derived a simple expression showing that complexity due to sediment mixing was balanced by the rules of sediment supply. This work opened the way to a whole generation of quantitative studies of erosion rates and their variation with factors such as climate, tectonics, and land use.

Over the years, Kirchner’s research has covered a broad range of topics from watershed hydrology and contaminant transport to speciation and extinction in the fossil record. Through it all, he has used the same analytical approaches and sharp insight to great effect, establishing himself as an international leader across a variety of disciplines. Kirchner is a remarkable scientist and polymath whose fundamental and innovative contributions to the field of geomorphology emphatically merit the Ralph Alger Bagnold Medal.