Landslide is a Landslide is a Landslide...Or Is It. Defining Landslide Potential Across Large Landscapes

摘要

Not all landslides are created equal. Some have the potential to run out to streams and others do not. Some are likely to simplify and damage stream habitat, and others can be important sources of gravel and large wood, fundamental components of habitat complexity for salmon and other stream inhabitants. Forest managers want to avoid negative consequences and promote positive characteristics of debris flows. Until recently, however, approaches to assess whether landslides will enter streams over large areas have been unavailable. Scientists at the Pacific Northwest Research Station and their collaborators at Earth Systems Institute developed techniques to estimate densities of landslides over an entire region and specify confidence in those estimates. Landslide densities are estimated as a function of topography and forest cover from elevation data, forest mapping, and landslide inventories. Existing field- and air-photo-based landslide inventories are used together to capitalize on the strengths and overcome the deficiencies in each. For the first time, source areas for landslides can be differentiated between those likely and unlikely to affect streams. This can help decisionmakers more effectively regulate timber harvest and target forest management and restoration activities. Researchers also found that locations with the highest probabilities of initiating and delivering debris flows to fish-bearing streams can be managed by concentrating on a small percentage of the landscape.