ABSTRACT
In the steep, rugged terrain of the Oregon Coast Ranges (USA), heavy precipitation often triggers numerous shallow landslides. While it is well documented that wet antecedent soil-moisture conditions, intense or sustained rainfall, and steep, convergent topography provide the necessary conditions for slope failure, it is difficult to predict exactly when and where landslides will occur. The long-term objective of this study is to improve quantitative characterization of the hydrologic conditions leading to weather-induced landslides in the Oregon Coast Range. The work presented here uses a distributed numerical model of 3D variably saturated subsurface flow, coupled with the infinite-slope stability model to evaluate the effect of topography and soil conditions on landslide potential under variable rainfall conditions. The modeling relies on observations from a well-characterized zero-order basin in the Elliott State Forest for model parameterization and performance evaluation.
