US wildfire management strategy has changed from “fighting with wildfires” to “living with wildfires”, which focuses on communities adapting to and coexisting with fires. Post-wildfire slope stability issues (i.e., erosion, landslide, debris flow) are cascading risks to community adaptation. Post-wildfire landslides are a particular risk because the fundamental initiation mechanisms are not yet understood. As a result, there is no wildfire-specific approach to evaluating the landslide susceptibility of burned hillslopes. This talk presents preliminary results of a study that was the first effort towards understanding the fundamental changes in soil behavior post-wildfire over time and the implications to hillslope stability. A slope burnt by 2019 Williams Flats Wildfire in Colville Indian Reservation near Keller, WA was instrumented with suction and water content sensors to monitor the evolution in root suction over time at a burnt and an unburnt location. Soil and ash samples were collected periodically over a year after the fire to determine the changes in physicochemical and mechanical soil behavior. The results are presented in this talk and the implications to hillslope stability are discussed through suction stress. Field observations and the vision for future work are presented.

Dr. Idil Akin is an assistant professor in Civil and Environmental Engineering at Washington State University. She earned her PhD (2017) and MS from University of Wisconsin-Madison CEE, and her BS from Middle East Technical University CE. MIT Department of Civil Engineering named her as a “Rising Star” for her PhD work on internal stress state of unsaturated clays. She joined WSU in 2017, where she developed an active teaching and research program in unsaturated soil mechanics and biogeotechnics. Her research and teaching efforts were recently recognized by the NSF CAREER Award. Her primary research focus is on the fundamental mechanisms that control physicochemical, mechanical, and hydraulic soil behavior. Her current research is in post-wildfire slope stability and bio-inspired and bio-mediated geotechnics. She also leads projects related to waste containment systems, particularly focusing on geosynthetic clay liners. She applies her fundamental research approach to solve multi-disciplinary problems in collaboration with researchers from many different areas of science and engineering including chemical engineering, materials engineering, environmental engineering, crop and soil science, and biology.