Annual Surface Elevation Change of the Lehman Rock Glacier in Great Basin National Park, Nevada, USA

Authors: John-Morgan Manos*, The Ohio State University, Bryan Mark, The Ohio State University, Department of Geography, James DeGrand, The Ohio State University, Department of Geography, Oliver Wigmore, University of Colorado Boulder, Institute of Arctic and Alpine Research
Topics: Physical Geography, Mountain Environments, Geomorphology
Keywords: Glacier Environmental Change, Rock Glacier, Geomorphology, Geographic Information Systems, Physical Geography
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: Download

Mid-latitude, mountain glaciers are a critical reserve of fresh water for local populations and are threatened by a rapidly changing climate. Specifically, the Lehman Rock Glacier in Great Basin National Park in western Nevada has little perennial, exposed ice left with the rock glacier being the predominant extant ice feature. In order to determine how dynamic the rock glacier is and better understand its geomorphology, we performed annual surveys of the surface beginning in 2015. Using balloon-borne photogrammetry, >600 images spanning a study area of ~ .1 square kilometers were taken at an altitude ~500 feet above the surface. A Surface-from-Motion technique in conjunction with ground control points (GCPs), 7 used in the 2015 model and 16 used in the 2016 model, allowed us to reconstruct the surface from incident aerial photographs. Accuracy points, 15 points in 2015 and 25 points in 2016, were used to assess errors in model reconstruction. GPS points were post-processed and differential corrected allowed for ~ .001 meter vertical resolution measurements. We developed our 3-dimensional models of the rock glacier using Agisoft Photoscan and exported digital elevation models as well as orthorectified images in their respective years. Using ArcMap, the 2015 DEM model raster was subtracted from the 2016 DEM model raster. Results indicate that annual surveys using differentially corrected GPS produce high quality DEMs with an average elevation offset of ~ 0.30 m. Comparing DEMs showed elevation varies spatially ranging from +1.5 m to – 1.0 m.

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