An Overview of the Washington State Department of Natural Resources, Forest Practices Division's Landslide Hazard Zonation Project Methodology and Products for Identification of Unstable Slopes

Landslides are triggered by extrinsic factors (such as earthquakes, unusual rainfalls, forest practices, and land use changes) and intrinsic factors (such as geology, slope, vegetation, and geotechnical soil properties). They can deliver significant volume of material to streams and lowlands, affecting and damaging human settlements, industrial development, agricultural, and forest activities. There is a necessity to study and characterize areas that are prone to slope instability. Geologists of the Washington State Department of Natural Resources (DNR), Forest Practices Division have been conducting multi-temporal landslide inventories and producing landform hazard maps to assist Washington State's forest practices rules. This poster aims at illustrating the innovative methodology used by the Landslides Hazard Zonation (LHZ) Project. The landslide and landform mapping techniques and their implementation in a GIS-base technology is presented and discussed. LHZ geo-datasets, reports, landslide inventory maps, and landform hazard maps are available for each Watershed Administrative Unit (WAU) at http://www.dnr.wa.gov/BusinessPermits/Topics/LandslideHazardZonation/Pages/fp_lhz_completed.aspx