RAPID: Post-fire lidar change detection, Eagle Creek fire, Columbia River Gorge, Oregon

University Of Oregon Eugene, Eugene OR

Investigators

Abstract

Increased wildfire activity in the Western U.S. significantly increases the likelihood of rapid, highly destructive debris flows as well as contributes to rapid soil erosion and rockfall. Debris flows emanate from steep catchments where they entrain sediment and debris before entering adjacent lowlands, and thus, they pose an increasingly significant threat to human life and infrastructure. In September 2017, the Eagle Creek fire complex burned nearly 50,000 acres of steep, forested terrain along the southern margin of the Columbia River Gorge in Oregon. Data and field observations necessary to determine the relevance of post-fire geomorphic responses in the Eagle Creek fire region are lacking. This project responds to the severe urgency to collect data and field observations following the fire, and could impact management activities. This project will inform process-based geomorphic models of debris flow potential and provide important constraints on the contribution of extreme events to regional erosion and sediment yield. The work plan includes raster and point-cloud based change-detection with lidar datasets. Lidar analysis documenting changes in the forest and sub-canopy structure between 2014 and 2018 will enable the team to quantify how the disturbance of different components of the vegetation mosaic contribute to sediment transport. Analysis of post-fire land surface change will enable the team to test how grain size and slope angle regulate transport distances owing to disturbance. Fieldwork in summer 2018 will occur before mitigation activities overprint post-fire geomorphic change. The team will identify hillslope sites with thick sediment accumulation that are likely to produce debris flows and identify damage to infrastructure. Various state and federal agencies are involved and a graduate student will receive training from experts in lidar techniques. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.