Validation of digital elevation models from SRTM X-SAR for applications in hydrologic modeling

This study examines the quality of SRTM X-SAR DEMs for applicability in hydrologic modeling. Elevation profiling, image subtraction and ground control points are used to assess the general quality of the data. The relationship between the SRTM elevation error and the local incidence angle of the radar beam and the errors' dependence from land-cover distribution is demonstrated. Test and reference DEM are exposed to comparative digital terrain analysis techniques and are applied to the rainfall–runoff model TOPMODEL to investigate the impact of different topographies on soil moisture distribution and hydrograph simulation. Model results are related to deviations in the frequency distribution of the topographic index, leading to slightly modified runoff patterns and to marginally increased flood peaks under wet watershed conditions. While SRTM X-SAR DEMs partially show low accuracy in mountainous terrain primarily due to radar shadow effects, it can be concluded that the overall quality of the data sets is sufficient for hydrologic model applications.