I conduct field and theoretical studies of drainage-basin, hillslope, and fluvial geomorphology and of the application of hydrology and geomorphology in landscape management and hazard analysis. I study the stochastic and spatial aspects of the sediment supply to mountain river networks in which sediment loading of the channel system is driven by the interaction of wildfires, rainstorms, and spatially varying landscape properties. I have a particular interest in erosion and sedimentation on active volcanoes, including the role of debris flows. This work began after the 1980 eruption of Mt. St. Helens and has continued sporadically up to my current work on the origin and nature of post-wildfire debris flows in Southern California. I also continue to study sediment transport and sedimentation in floodplains of the Amazon River Basin and the Central Valley of California. I conducted these investigations as a faculty member at the University of Nairobi, McGill University, the University of Washington, and the University of California Santa Barbara.

Research Interests

Hydrology, sediment transport, and floodplain sedimentation (various parts of the Amazon R. basin and California Central Valley). Debris flow initiation and sediment transport (currently Montecito CA). Field and theoretical studies of hillslope evolution, incorporating the relations between climate, vegetation, hydrology, sediment transport, and Earth material properties (currently East Africa).

Membership Type


Election Year


Primary Section

Section 15: Geology

Secondary Section

Section 64: Human Environmental Sciences