Czesław Przybyła, Krzysztof Pyszny
Uniwersytet Przyrodniczy, Poznań

The article compares the accuracy of two digital elevation models Shuttle Radar Topography Mission (SRTM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model. Models were assessed in the context of possibility of their usage in hydrological modeling in the areas of low drop. The object of analysis is located in the agglomeration of Poznań. Detailed study sites were the catchment area of Junikowski Stream and catchment area of Tributary from Dopiewiec. The study used data from two free DEMs: SRTM, ASTER and as a reference, DEM model generated from the contour lines and elevation points from Vector Map Level 2 (VMAP L2). Analyses were performed using Free Open Source Software, Quantum GIS ver. Wroclaw and GRASS 1.7.4 ver. 6.4.2. Data analysis were also performed in spreadsheets in Microsoft Office Excel 2007. Hydrological analysis were conducted in r.watershed GRASS module. In the second part of the paper, for the comparative analysis, data from Raster Hydrographical Map of Poland was adopted. Research showed that the average difference occurring between the analyzed models are not significant, however, a large number of artifacts in the models can influence on the results of the hydrological analysis. It has been calculated that the SRTM model is more accurate than the ASTER data even though the ASTER model input resolution is higher. The results revealed that the SRTM is closer to the reference model. It should also be noted that used reference DEM, may contain errors. In the small catchments with low drop, catchment boundaries and river networks generated from the DEMs may contain errors affecting the results of the hydrological modeling. Using available and free DEMs (SRTM and ASTER) to generate catchment boundaries and streams networks, the results must be verified basing on field measurements or it has to be made on the basis of greater resolution data, e.g. from Airborne Laser Scanning LIDAR (Light Detection and Ranging). Due to the errors in the tested models it is not recommended to use data, especially from the ASTER, for large-scale studies in the areas of small drop. SRTM and ASTER DEMs, however are a valuable material for analysis in small and medium scales. Data from the analyzed models is a valuable source of information about the terrain and can be successfully used for the geomorphological and landscape analysis.

Słowa kluczowe
SRTM; ASTER GDEM; małe deniwelacje

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