Measuring Sedimentation Due to Frozen Debris Lobes within the Brooks Range, Alaska, Using LiDAR

摘要

Frozen debris lobes (FDLs) within the Brooks Range, Alaska, are elongated, lobate permafrost features that consist primarily of silty sand with gravel, are covered by mature spruce forests, and move primarily through basal shear. Over the last decade, researchers from the University of Alaska Fairbanks and the Alaska Division of Geological and Geophysical Surveys have studied FDLs, determining their current and historic rates of movement, composition, likely formation, and any hazards they pose to the adjacent infrastructure (i.e., the Dalton Highway and the Trans Alaska Pipeline System). Although most FDLs are some distance from the Dalton Highway, the Alaska Department of Transportation and Public Facilities (ADOT&PF) already experiences increased maintenance due to changes in sedimentation within certain streams that intersect the highway. Visual observations of FDL surface degradation suggest that sediment production will increase in the future. This is crucial for maintenance and operation of the Dalton Highway, as it is the only land-based transportation route to the Alaskan Arctic. In this paper we present an analysis of sedimentation along the Dalton Highway. We use two LiDAR-derived digital elevation models (DEMs) from 2011 and 2015 to conduct change detection and estimate volumetric sediment transport from FDLs and associated catchments, and from catchments without FDLs (or NDLs for "no debris lobe"). Results indicate that NDL catchments currently produce 1.5 times as much sediment as FDL catchments, suggesting that FDLs are effective sediment storage landforms. Identifying current sedimentation areas and volumes provides ADOT&PF with a long-term maintenance planning tool.