Topographic change detection at Chalk Cliffs, Colorado, USA, using Airborne LiDAR and UAS-based Structure-from-Motion photogrammetry

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Abstract

The Chalk Cliffs debris-flow site is a small headwater catchment incised into highly fractured and hydrothermally altered quartz monzonite in a semi-arid climate. Over half of the extremely steep basin is exposed bedrock. Debris flows occur multiple times per year in response to rainstorm events, typically during the summer monsoon season. The frequency of debris flows, and the uniformity of the underlying rock, make Chalk Cliffs an ideal study catchment for translating mechanistic understanding of natural debris flows to other sites. A 2008 National Center for Airborne Laser Mapping (NCALM) Airborne LiDAR survey provides baseline topography for the site; however, heretofore there has been no systematic effort to collect repeat topography of the entire site. Starting in May 2018, we made repeat surveys of the basin with an unmanned aircraft system (UAS). The UAS-based imagery was processed into (x, y, z) point clouds using Structure-from-Motion (SfM) photogrammetry. We geo-registered the point clouds using 12 ground control points placed within and around the study basin. In this study we compare the LiDAR with one SfM point cloud to assess topographic change over a 10-year time period. The difference map provides observational data relevant to understanding sediment provenance and transport at the Chalk Cliffs. The difference image indicates erosion of colluvial surfaces, with limited deposition in the survey area. Some colluvial hillslopes show spatially uniform erosion while others experienced concentrated erosion of up to three meters depth over a ten-year period.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Topographic change detection at Chalk Cliffs, Colorado, USA, using Airborne LiDAR and UAS-based Structure-from-Motion photogrammetry
Volume 7
Year Published 2019
Language English
Publisher Mountain Scholar
Contributing office(s) Geology and Geophysics Science Center, Geologic Hazards Science Center
Description 8 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title Debris-flow hazards mitigation : mechanics, monitoring, modeling, and assessment ; proceedings of the Seventh International Conference on Debris-Flow Hazards Mitigation
First page 85
Last page 92
Conference Title Seventh International Conference on Debris-Flow Hazards Mitigation
Conference Location Golden, CO
Conference Date June 10-13, 2019
Country United States
State Colorado
Other Geospatial Chalk Cliffs