Effects of forest cover, topography, and sampling extent on the measured density of shallow, translational landslides.

Abstract

We use regionally available digital elevation models and land-cover data, calibrated with ground- and photo-based landslide inventories, to produce spatially distributed estimates of shallow, translational landslide density (number/unit area) for the Oregon Coast Range. We resolve relationships between landslide density and forest cover. We account for topographic variability between sites and landslide detection bias in air-photo mapping. Even so, ratios of landslide density in forest classes differ among sites. We present strategies for subsampling available data to quantify this variability. We find that older forests, when sampled over tens of square kilometers, commonly exhibited the highest landslide densities, but over hundreds of square kilometers, always exhibited the lowest densities averaging 30 percent of that in recently harvested areas and 79 percent of that in younger, managed forests.

Citation

Miller, D.J.; Burnett, K.M. 2007. Effects of forest cover, topography, and sampling extent on the measured density of shallow, translational landslides. Water Resources Research. 43: W03433. doi: 10.1029/2005WR004807.