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Aerial imagery and structure-from-motion derived data products from a UAS survey of the debris flow at South Fork Campground, Sequoia National Park, CA

December 19, 2024

This data release presents aerial imagery and digital topography to support a geohazards assessment for an area of Sequoia National Park affected by debris flows in January 2023. Multiple atmospheric-river storms brought heavy precipitation to Sequoia National Park and the surrounding region in December 2022 and January 2023, triggering slope failures. Storm rainfall on January 9, 2023, led to shallow landslides, overland-flow erosion, and debris flows from north-facing drainages above the South Fork Kaweah River. Three of the debris flows in that part of the park buried and damaged federal assets and infrastructure: the South Fork Campground, the road used to access the campground and adjacent trails, and drainage culverts beneath the road.

The U.S. Geological Survey (USGS) used uncrewed airborne systems (UAS) and real-time kinematic (RTK) Global Navigation Satellite System (GNSS) to survey the largest of the three debris flows in April 2024. The UAS flights were conducted with authorization from the National Park Service. The UAS was launched from a relatively flat and vegetation-free sediment surface near the downstream end of the debris-flow deposit. Imagery, video, and digital topographic surfaces derived from structure-from-motion photogrammetry are presented in this data release, covering approximately the downstream-most 1.3 kilometers of the debris-flow runout zone, including its confluence with the South Fork Kaweah River. Although several shallow landslides appear in the imagery, additional apparent debris-flow source areas (identified by project scientists using separate satellite imagery) were not included in this USGS dataset due to their being beyond the line-of-sight operating range from the UAS launch site. This data release supersedes preliminary products provided earlier to the National Park Service for emergency response purposes.

Publication Year 2024
Title Aerial imagery and structure-from-motion derived data products from a UAS survey of the debris flow at South Fork Campground, Sequoia National Park, CA
DOI 10.5066/P144KDGN
Authors Joshua Logan, Amy East
Product Type Data Release
Record Source USGS Asset Identifier Service (AIS)
USGS Organization Pacific Coastal and Marine Science Center
Rights This work is marked with CC0 1.0 Universal
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