STORM INDUCED MASS WASTING ON DISTURBED SLOPES ACROSS A THIRTY-FOUR YEAR TIMELINE

Over decades, the Eldorado National Forest landscapes have experienced multiple disturbances including numerous events of wildfires, flooding, atmospheric river drenching, and rapid snowmelt which have promoted landslide activity over a palimpsest of forest management activities and post-fire recovery.

LiDAR provides a very effective way to identify unstable landforms and capture the occurrence of mass wasting over broad regions rapidly. Lidar facilitates an accurate and detailed identification and mapping of mass wasting features. Multitemporal lidar was used to identify mass wasting features and judge their activity in relation to various managed forest conditions due to a series of stressing storms that triggered widespread landslides in 2017, resulting in a federal disaster declaration. Three pre-storm lidar datasets that covered previously burned areas were compared to a post-2017 storm survey to reveal triggered slope movements in separate disturbed slopes that burned in 1992, 2004, and 2014 where two generations of aerial lidar data exist. We used lidar differencing techniques to reveal differences in slope response based on the length of the recovery time since disturbance at intervals of 3, 13, 25, and 34 years. Results will reveal the effects of vegetation change and management actions on slope stability.