Erik Bollmann

QUANTIFICATION OF GEOMORPHODYNAMICS IN GLACIATED AND RECENTLY DEGLACIATED TERRAIN BASED ON AIRBORNE LASER SCANNING DATA

Sailer, R., Bollmann, E., Hoinkes, S., Rieg, L., Sproß, M. and Stötter, J., 2012. Quantification of geomorphodynamics in glaciated and recently deglaciated terrain based on airborne laser scanning data. Geografiska Annaler, Series A: Physical Geography, 94, 17–32. doi:10.1111/j.1468‐0459.2012.00456.x ABSTRACT This article highlights the ability of airborne laser scanning (ALS) to detect, map and quantify geomorphological processes in high alpine environments. Since 2001, ALS measurements have been carried out regularly at Hintereisferner (Ötztal Alps, Tyrol, Austria), resulting in a unique data record of 18 ALS flight campaigns. The quantifications of volumetric earth surface changes caused by dead‐ice melting, fluvial erosion/deposition, rock‐fall activity, gravitational displacements and permafrost degradation in glaciated, recently deglaciated and periglacial terrain is based on the analysis of ALS point clouds (vector data) to preserve the high quality of the data. We present inter‐annual, annual and perennial trends of geomorpho‐dynamically induced topographic changes. The most significant changes occurred at two dead ice bodies (−0.48 m and −0.24 m respectively per year). At a complex rock fall site, mean annual vertical changes of −0.25 m are observed in the source area, respectively 0.25 m of deposited material in the run‐out area. Fluvial erosion processes are connected with subsequent gravitational denudation, reallocation and deposition. Topographic changes caused by fluvial erosion between 2001 and 2009 range from −0.68 m to −1.20 m. Surface elevation increase caused by fluvial accumulation is found to be 0.48 m from 2001 to 2009. Minor annual surface elevation changes (between −0.05 m and −0.10 ma−1) are detected in permafrost areas. Finally, the significance of the process‐dependent topographic change rates is assessed, regarding the accuracy of the ALS data, the magnitude of the process, the time lapse between the single ALS‐campaigns and disturbing factors (e.g. snow cover). For processes with high magnitudes time lapse rates can be shorter than one year and disturbing factors have only minor influences on the results. In contrast, results of processes with low magnitudes gain relevance with an increasing time lapse between the ALS campaigns, the frequency of flight campaigns and if disturbing factors can be excluded.