Measuring the Topograpy and Motion of the El Altar Rock Glacier in the Cordillera Frontal, Argentina

Authors: Adrienne Shumlich*, University of Delaware
Topics: Geographic Information Science and Systems, Cryosphere, Spatial Analysis & Modeling
Keywords: Argentina, Rock Glacier, Photogrammetry
Session Type: Poster
Day: 4/12/2018
Start / End Time: 1:20 PM / 3:00 PM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded

GPS and digital photogrammetry are used to obtain topographic and motion data for the El Altar Rock Glacier in the Dry Andes of Argentina. 784 aerial images were used to obtain 5.2 million topographic points and subsequent elevation, shaded relief, and slope models with 0.25 m resolution. Geometric data extracted form these models indicate the following: an area of 65,400 m2, a 430 m long axis, and a maximum width of ca. 210 m tapering to ca. 100 m at the terminus. Geomorphic analyses, based on the surface topography, were used to identify 10 transverse lobes extending from the accumulation area to 210 m down valley on a slope of 13°. Likewise, the lower half of the glacier, with a slope of 7°, is characterized as hummocky terrain that is depressed several meters below raised terminal ridge. This geomorphology, coupled with elongated and nested lateral furrows present a picture of deformation and flow down valley over time. Analysis of the vectors at the 8 survey stakes suggests motion along the upper transverse ridges is approximately 2 to 5 times faster than motion along the terminal margin (ca. 0.16 m yr-1 vs. 0.2 m yr-1). Although slower at the terminus, its velocity maintains the margin at the angle of repose (32°). Our results, most of which would be impossible without high resolution topographic data, underscore the value of coupling aerial imagery with sparse data like our GPS measurements to provide insight for future analyses focused on ice presence and volume.

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