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Using high sample rate lidar to measure debris-flow velocity and surface geometry

January 8, 2021

Debris flows evolve in both time and space in complex ways, commonly starting as coherent failures but then quickly developing structures such as roll waves and surges. These processes are readily observed but difficult to study or quantify because of the speed at which they evolve. Many methods for studying debris flows consist of point measurements (e.g., flow height or basal stresses), which are inherently limited in spatial coverage and cannot fully characterize the spatiotemporal evolution of a flow. In this study, we use terrestrial lidar to measure debris-flow profiles at high sampling rates to examine debris-flow movement with high temporal and spatial precision and accuracy. We acquired measurements during gate-release experiments at the U.S. Geological Survey debris-flow flume, a unique experimental facility where debris flows can be artificially generated at a large scale. A lidar scanner was used to record repeat topographic profiles of the moving debris flows along the length of the flume with a narrow swath width (∼1 mm) at a rate of 60 Hz. The high-resolution lidar profiles enabled us to quantify flow front velocity of the debris flows and provided an unprecedented record of the development and evolution of the flow structure with a sub-second time resolution. The findings of this study demonstrate how to obtain quantitative measurements of debris-flow movement. In addition, the data help us to quantitatively define the development of a saltating debris-flow front and roll waves behind the debris-flow front. Such measurements may help constrain future modeling efforts.

Citation Information

Publication Year 2021
Title Using high sample rate lidar to measure debris-flow velocity and surface geometry
DOI 10.2113/EEG-D-20-00045
Authors Francis K. Rengers, Thomas D Rapstine, Michael Olsen, Kate E. Allstadt, Richard M. Iverson, Ben Leshchinsky, Maciej Obryk, Joel B. Smith
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental and Engineering Geoscience
Series Number
Index ID 70222486
Record Source USGS Publications Warehouse
USGS Organization Geologic Hazards Science Center