Who doesn’t love the postcard views of snow-covered mountains in the Pacific Northwest — Mt. Hood from the Portland Rose Garden or Mt. Rainier from the Space Needle in Seattle? But all it takes is a switch in the weather to turn beauty to disaster. A research project led by Oregon State University geologist Anne Nolin and funded by the American Reinvestment and Recovery Act is addressing the landslides and floods that follow rain on snow. For example:
- Mt. Hood, Christmas Day, 1980 — an intense rainstorm melted snow and triggered a landslide in upper Polallie Creek, leading to more than $13 million in damage to roads, bridges and a state park.
Photo of Mt. Hood courtesy of NASA
- Mt. Rainier National Park, November 2006 — flooding and landslides caused by a fast-moving rainstorm destroyed roads, bridges and campgrounds. For the first time in its history, the park closed for six months to make nearly $30 million in repairs.
- Mt. Hood, November 2006 — the same storm destroyed a bridge and roadway, delaying the opening of one of the region’s premier ski area for several weeks. Landslides threatened water diversion structures managed by the Middle Fork Irrigation District.
Nolin is working with Gordon Grant of U.S. Forest Service Research and Stephen Lancaster of OSU to characterize the conditions that set the stage for floods and debris flows and to map where these events begin. With an eye on changing climate, they will review data on retreating glaciers and storm intensity. Already this project has shown that the storms leading to these debris flows are significantly warmer than other storms in the same season. High-elevation rainfall occurs where glaciers have been retreating.
The project will provide decision-makers with a scientific basis for risk assessment to roads, bridges, buildings and other types of infrastructure.