Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 5 6 2005 10.5194/nhess-5-863-2005 http://www.nat-hazards-earth-syst-sci.net/5/863/2005/ http://www.nat-hazards-earth-syst-sci.net/5/863/2005/nhess-5-863-2005.html http://www.nat-hazards-earth-syst-sci.net/5/863/2005/nhess-5-863-2005.pdf 863 876 2005-11-08 Validation of Digital Elevation Models around Merapi Volcano, Java, Indonesia C. Gerstenecker G. Läufer D. Steineck C. Tiede B. Wrobel Institute of Physical Geodesy, Darmstadt University of Technology, Darmstadt, Germany Institute of Photogrammetry and Cartography, Darmstadt University of Technology, Darmstadt, Germany The accuracy of 4 Digital Elevation Models (SRTM30, GTOPO30, SRTM3 and local DEM produced from aerial photogrammetric images) for the volcanoes Merapi and Merbabu in Java, Indonesia is investigated by comparison with 443 GPS ground control points. The study confirms the high accuracy of SRTM3 and SRTM30, even if the a priori defined 90% confidence level of 16 m for the SRTM3 is not always achieved in this mountainous region. Accuracy of SRTM30, GTOPO30 and SRTM3 is mainly dependent on the altitude itself and the slopes' inclinations, whereas the photogrammetric DEM exhibits constant accuracy over a wide range of altitudes and slopes. For SRTM3 and SRTM30 a statistically significant correlation between heights and aspects of the slopes is also found. </p><p style="line-height: 20px;"> Accuracy of DEMs which are generated by interpolation on a finer grid does not change significantly. Smoothing of DEMs on a coarser grid, however, decreases accuracy. The decrease in accuracy is again dependent on altitude and slope inclination. </p><p style="line-height: 20px;"> The comparison of SRTM30 with GTOPO30 exhibits a significant improvement of SRTM30 data.