Field Reconnaissance: 18 November 2004

LIDAR System of Debris Flow

Robert Pack, Randy Jibson, and James Bay

GEER Beyond Reconnaissance Team

A LIDAR survey of a debris slide / debris flow complex was completed on November 18, 2004. The slide is located near Nagaoka in a canyon to the north of the Yamakoshi Village area. This landslide was chosen as it was considered typical of many debris flows generated in the region. The survey was principally conducted from an instrument setup on the debris deposit and looking up. A second setup was located at the head scarp and a third below the road where most of the debris deposited. The data indicate that the slide has a relief of approximately 100 meters and an average transport gradient of 26°.

Fig. 1. Overview of debris slide that initiated at a road fill, mobilized into a debris flow, then deposited on a road in the foreground.

Fig. 2. Location where debris slide initiated (note LIDAR instrument setup on side scarp).

Fig. 3. View of debris flow deposit from above.

Fig. 4. LIDAR instrument setup location used to determine debris flow profile.

Fig. 5. Image acquired by camera on the LIDAR system. Note the location of the profile extracted and shown below.

Fig. 6. LIDAR-derived profile of debris slide. It indicates that the total relief is just under 100 m with an average transport angle of 26°.