USING ASTER AND SRTM DEMS FOR STUDYING GLACIERS AND ROCKGLACIERS IN NORTHERN

Digital elevation models (DEMs) derived from satellite data are increasingly used for geomorphologic and glacial analysis. Recently, digital elevation data from the Space Shuttle Radar Topography Mapping Mission (SRTM) in ~90m grid resolution is available for many parts of the earth. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) produces simultaneous stereo-pair data allowing the generation of detailed DEMs with a resolution of 15 to 30m. ASTER-DEMs have been generated for selected areas in Sailiskiy and Kungey Alatau. The analyses were verified with results from field work. Clouds represent one of the main problems in ASTER DEM generation; such cloud-covered areas were marked, clipped and filled with SRTM data. The accuracy of the DEM was evaluated by comparison with a DEM derived from contour maps. With the help of geomorphic analyses and satellite images a map of the glaciers and rockglaciers could be produced. Using the Software ArcGIS the area, geomorphic features and solar radiation conditions of selected glaciers and rockglaciers was calculated. The results show that the DEM is of good acuracy and is useful for an interpretation of the macroand mesorelief. Introdution A DEM offers the most common method for extracting topographic information and enables the modeling of surface processes. DEMs play also an important tool for the analysis of glaciers and glaciated terrains (Bishop et al. 2001, Kaeaeb et al. 2002, Duncan et al. 1998, Etzelmüller & Sollid 1997, Kaeaeb et al. 2002, Sidjak & Wheate 1999). To accomplish this, the DEM must represent the terrain as accurately as possible. DEMs can be generated from contour lines, with radar-interferometry such as the SRTM-DEM or stereo satellite data derived from electro-optic scanners such as ASTER. This report presents a DEM derived from ASTER and SRTM data of Sailiskiy and Kungey Alatau (Kasakhstan/Kyrgyzstan). Fieldwork was conducted in several valleys in late Summer 2002 and 2003 and focussed on obtaining GCPs from GPS and geomorphological mapping with special respect to glacial and periglacial forms. Satellite data (Landsat ETM7, year 1999 and ASTER, years 2000 and 2001) were used for orientation and support mapping. As fieldwork was not possible in the whole northern Tien Shan, a detailed, realistic geomorphological mapping of the entire area is only possible with the help of DEM data. This report Proceedings Part I of the Conference “Teoretischeskije i Prikladnyje Problemy geografii na rubeschje Stoletij (Theoretical and applied problems of geography on a boundary of centuries)”, Almaty/Kasakhstan, 8/9 th June 2004, p. 254258. presents the first results of an ongoing work, in which the actual situation and the possible change of geomorphology and glaciers is studied.