The frequency, intensity, and areal extent of wildfires in the Western United States are increasing. Changes imposed on watersheds during and after burning result in a dramatic increase in debris-flow occurrence and magnitude, which in turn poses risks to human life and property, especially as the urban-wildland interface advances into mountainous areas. Flows can be initiated following wildfire by low intensity rainfall events, and they grow substantially in volume through channel scour while in transit. On average, flow volumes are 3-5 times larger immediately after wildfires, and the volume magnification effects linger for 1-3 years before the watershed recovers. Volume is difficult to predict accurately, but it can be estimated using multiple linear regression models that rely on GIS-friendly inputs such as area burned, rainfall totals, and watershed slope characteristics. A new probabilistic model has been shown to be more accurate and it relies on even fewer terms. Discharge rates and velocity are also difficult to predict, but reasonable ranges are given using databases of previous field measurements. Damming and avulsion of the flows make runout patterns unpredictable, but recent studies have helped to quantify the process.

Paul Santi is the 2016 AEG President. He is also the Department Head of the Department of Geology and Geological Engineering at the Colorado School of Mines, where he has been on the faculty for 14 years. Previously, he taught for 6 years at the Missouri University of Science and Technology, and worked for 6 years as an engineering consultant in San Francisco and Denver. His recent research has focused on analysis, prediction and mitigation design for debris flows, landslide dewatering and analysis, engineering geology pedagogy, and general geologic hazard analysis. He holds Bachelor's degree in Geology and Physics from Duke University, an MS in Geology from Texas A&M, and a PhD in Geological Engineering from the Colorado School of Mines.