Post-fire rockfall and debris-flow hazard zonation in the Eagle Creek Fire burn area, Columbia River Gorge, Oregon: a tool for emergency managers and first responders

The Eagle Creek Fire engulfed 48,832 acres (196 km2) within the Columbia River Gorge, Oregon beginning September 2nd and was 100% contained by November 30th, 2017. The Columbia River Gorge area is steep and heavily forested characterized by cliffs and flanking talus slopes, receiving > 100 inches (> 254 cm) of precipitation annually. The Columbia River Gorge is a critical lifeline for Oregon and Washington, including interstate highway 84 (I-84) and state route 14 (SR-14), commercial train lines, freight traffic, major pipelines, shipping corridor, 1,000s of permanent residents, tourists and motorists, and major hydroelectric dams. Before the Eagle Creek Fire, there was significant landslide and debris-flow hazard. More than 80 landslides have been recorded in the Gorge during the last ~100 years, with 58 of these recorded in the exceptionally wet and stormy winters of 1996 and 1997. Several of these landslides damaged property and temporarily closed I-84, train and ship traffic. There is some uncertainty on the degree to which the fire will enhance debris-flow susceptibility, because the climate, terrain and geology is different from the regions where most post-fire debris-flow research has been conducted. A large portion of the Columbia River Gorge National Scenic Area, including popular hiking trails, remain closed 18 months after the fire, with the Historic Columbia River Highway opened 14 months after the fire. In the aftermath of the Eagle Creek Fire, emergency managers and first responders identified a critical need for a post-fire landslide response plan and hazard map. The Oregon Department of Transportation (ODOT), the Oregon Department of Geology and Mineral Industries (DOGAMI), and the U.S. Geological Survey (USGS) participated in the creation of the plan including making a landslide hazard map specific to their outlook, which includes swift decision making during emergencies such as landslide or flood events. This paper presents a perspective of post-fire debris flow-hazard response and assessment from the Eagle Creek burn area in the Columbia River Gorge, Oregon.