LANDSLIDE DIFFERENTIAL, INVENTORY, AND SUSCEPTIBILITY MAPPING USING LIDAR IMAGERY FOR THE PANTHER CREEK WATERSHED IN YAMHILL COUNTY, OREGON

Landslides in the Panther Creek Watershed of the Oregon Coast Range impact the drinking water supply of the city of Carlton, Oregon which obtains its water from Carlton Reservoir. In 1999, a landslide flowed into the reservoir, resulting in a 50 percent decrease in the reservoir’s capacity. Due to this event, an assessment of the potential for future landslides was deemed necessary.

LiDAR (Light Detection and Ranging) was flown twice in the Panther Creek Watershed in 2007 and in the spring of 2009. The data collected was used to create LiDAR bare earth digital elevation models (DEMs) for each of the flights. Using ArcGIS 9.3, the LiDAR bare earth DEMs were subtracted relative to one another to see changes in ground elevation. The purpose of this process was to locate areas with a decrease in elevation at the top of a particular area and an increase in elevation at the bottom of the same area. These changes in elevation indicate a possible landslide. These areas were mapped on the LiDAR DEMs to find landslides that had occurred in the Panther Creek Watershed area over the past two years, which included a major storm event that occurred in January, 2009. These new landslides were added to a landslide inventory database which was also created using the bare earth LiDAR DEMs. The purpose of this project was to create a landslide inventory and susceptibility map for the study area. This project will also develop procedures for mapping landslides that occurred between two periods of LiDAR imagery.