GEOSPATIAL ANALYSIS OF FROZEN DEBRIS LOBE HISTORIC MOVEMENT, DALTON HIGHWAY, ALASKA

Historic imagery analysis is used to characterize the movement behavior of frozen debris lobes (FDLs), which are slow-moving landslides in permafrost areas. Aerial and satellite imagery, and data obtained using Light Detection And Ranging (LiDAR) and Interferometric Synthetic Aperture Radar (IfSAR) techniques, ranging from 1955 to 2014, were acquired for the study area of eight FDLs in the Dalton Highway corridor, north of Coldfoot, Alaska. Each scene was orthorectified and, where possible, joined to adjacent scenes as a mosaic. The catchment area and extent of each FDL were determined using 2011 LiDAR data. Changes in FDL size and position going back to 1955 and forward to 2014 were mapped and measured in a GIS environment and compared to recent surface surveys. Over the imagery timeframe, all FDLs demonstrated downslope movement; however, preliminary analysis suggests that pulses of movement among the FDLs have been asynchronous. Here we present a summary and comparison of FDL movement rates from the GIS analysis, coupled with field observations of vegetation patterns and geomorphic expression.