The digital topographic map products meet Interferometric Terrain Height Data (ITHD)-2 specifications: at 30 30 m spatial sampling, the absolute vertical height accuracy (90% linear error) is 16 m. The absolute horizontal accuracy (90% circular error) is 20 m (http:// www.jpl.nasa.gov/srtm/datafinaldescriptions.html). Due to restrictions imposed by the sponsoring agency (NIMA) and processing capabilities only 90 m (three arc second) resolution data was available for our area. More information about the SRTM mission can be found at http://www.jpl.nasa.gov/ srtm/.