Newly Published: Landslide Inventory and Susceptibility of the Columbia Gorge

We are excited to announce the publication of our Landslide Inventory and Susceptibility of the Columbia Gorge.

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Landslide Inventory and Susceptibility of the Columbia Gorge in Clark, Skamania, and Klickitat Counties, Washington

Abstract

Landslides are common in the Columbia Gorge due to the geologic setting, high relief, steep slopes, and abundant precipitation. In March 2017, the Washington Geological Survey (WGS) conducted a lidar-based landslide mapping project within a 900 square mile area on the Washington side of the Columbia Gorge. The data provided to counties and cities within the study area may increase resiliency to landslide hazards. Following published protocols, the WGS mapped existing landslides and modeled where landslides might occur in the future. The new inventory of landslides contains 2,163 landslides covering approximately 16.5 percent of the study area. The combined moderate and high areas of shallow-landslide susceptibility covers 56 percent of the study area. The combined moderate and high areas of deep-landslide susceptibility covers 52 percent of the study area. This updated landslide inventory and susceptibility analysis will increase awareness of landslide hazards in the Columbia Gorge and assist planners, emergency managers, public works departments, and those who live and work where landslides could impact their daily lives.

Suggested Citation: Mickelson, K. A.; Jacobacci, K. E.; Contreras, T. A.; Gallin, William; Slaughter, S. L., 2018, Landslide inventory and susceptibility of the Columbia Gorge in Clark, Skamania, and Klickitat Counties, Washington: Washington Geological Survey Report of Investigation 40, 11 p. text, with 2 accompanying ESRI file geodatabases.

https://fortress.wa.gov/dnr/geologydata/publications/ger_ri40_columbia_gorge_landslide_inventory.zip

You can also view these data and create custom landslide maps on the Washington Geologic Information Portal.

GIS Data for Download

The Survey also maintains two landslide databases: the Landslide Compilation and the new Landslide Inventory. Both datasets are on our Portal and are also available for download from our GIS Data and Databases webpage.

The new Inventory dataset follows a protocol that requires high-quality lidar data, available here.  So far, the dataset includes landslide inventory and susceptibility data for Pierce County and for the Columbia Gorge. We will add new data to this dataset as new inventories are published.

The Landslide Compilation dataset is just that: a compilation of published landslide data from throughout our agency and other published sources, including reconnaissance inventories after large landslide events, geologic mapping, and other watershed studies. Many of the landslides shown in this dataset were mapped without the benefit of lidar. Thus, any new mapping published through the Inventory supersedes what is contained within the Compilation.