Measurement of the water level in reservoirs from TerraSAR-X SAR interferometry and amplitude images

Measurement of water levels is important in many hydrological fields. Synthetic Aperture Radar (SAR) satellites, such as TerraSAR-X, TanDEM-X and COSMO-SkyMed, can provide useful high-resolution images for inaccessible regions and over wide areas. This letter has two research goals. First, an accurate boundary line between a dam slope and a water body was extracted using the SAR Edge Detection Hough Transform (SEDHT) approach, as proposed here. Second, after Digital Elevation Model (DEM) generation using SAR interferometry, the reservoir water level is measured. This approach will be helpful to estimate water level accurately at limited areas without emergent vegetation for double bounce that is required for conventional interferometric SAR (InSAR) approach. As a result of applying to two images of TerraSAR-X data in the study areas, the mean water level was determined to be 151.13 m on 5 November 2010 and 150.69 m on 16 November 2010 through the proposed method. The water level according to gauge data was 151.22 m on 5 November 2010 and 150.68 m on 16 November 2010, thus showing a water level difference of -9 cm and 1 cm, respectively.