干旱区生态环境知识资源中心

New remote sensing data allow the calculation of area-wide high-resolution elevation models. Especially in regions that are devoid of detailed topographic maps, such elevation data are a valuable base for various investigations.

First an evaluation of elevation data from the ASTER-sensor (resolution 30 m) and the Shuttle Radar Topography Mission (SRTM-3, 3 arc seconds, approx. 90 m) in comparison with the German digital elevation model (DGM 50,50 m) is given. In relation to the DGM 50 the ASTER model shows height deviations of +/- 5.9 m, whereas the SRTM-3 model has a Z-error of +/- 6.9 m. SRTM-3 data are useful for investigations up to scale of 1:100,000. Because of the used radar sensor clouds and vegetation are not interfere the data but the building development have to take into account. ASTER data with its higher resolution are useful for investigations up to a scale of 1:50,000 but the merging of the individual scenes is complex. In addition, clouds, a higher vegetation cover, or high-density areas influence the elevation data. In nearly barren and uninhabited regions, these limitations are negligible but we found evidence that thick sand accumulations (e.g. dunes) disturb the calculation of the SRTM-3 elevation data. Examples of use from the Western Desert of Egypt show that the derived morphometric parameters are useful for geomorphological and gcoarchaeological questions. Regarding the geomorphologic evolution of the escarpment near the Egyptian oases Dakhla and Kharga we confirm the theory that the wadis were mainly formed along tectonic lines as a result of ground-water sapping. The comparison of the calculated palaeo-drainage net with archaeological field survey data in the escarpment foreland show a distinct correlation of relief positions that have a surplus of surface water (e.g. endorheic basins) with the location of archaeological sites.