COLLABORATING WITH STAKEHOLDERS FOR EFFECTIVE LANDSLIDE HAZARDS COMMUNICATION: A FIRST ATTEMPT AT A LIDAR-DERIVED, COUNTY-WIDE LANDSLIDE INVENTORY IN WASHINGTON (Invited Presentation)

The Washington Geological Survey’s Landslide Hazard Program (LHP) was created in early 2016 as a result of legislative funding following the 2014 SR-530 “Oso” landslide. The LHP has commenced a lidar-based landslide mapping program for the state of Washington. The primary goal is to help Washington communities reduce losses from landslides by mapping landslides, producing hazard and vulnerability maps, and assisting at-risk communities.

Previously, landslides in the state were remotely mapped using aerial images and 10-meter DEMs. The landslide protocols followed at the time did not concentrate landslide hazard mapping in population centers and focused primarily on managed timberlands. In March 2016, the LHP collaborated with Pierce County, the second most populous county in the state, to improve and expand the existing landslide inventory in order to highlight assets at risk to landslide hazards.

Following protocols developed by Oregon’s Department of Geology and Mineral Industries, the LHP used 2-meter lidar to produce landslide inventory maps, and deep and shallow landslide susceptibility maps. At the onset of this project, the LHP collaborated with county stakeholders including planners, GIS specialists, emergency managers, and engineers to identify areas to map and assets to include in a vulnerability/exposure analysis. This analysis spatially identifies the intersection of public and private assets at risk either due to reactivation of an existing landslide or in areas identified as susceptible to future landslides.

By collaborating, the LHP delivered products that were applicable and informative to users, including the public. The LHP will further assist the county by conducting outreach at public meetings, distributing a homeowner’s guide to landslides, and by providing spatial and tabular data online at the Washington Geological Survey’s Geologic Information Portal. The data created from this project will allow Pierce County to evaluate the threat of landslides to people and property when considering future development and will provide the public with information on how to reduce their risk to landslide hazards. Through public outreach and the publication of maps and data, the LHP provides tools and assistance to inform public and private entities of landslide hazards across Washington State.