Digital Terrain Model Of The Varna And Beloslav Lakes (North Bulgarian Black Sea Coast)

Varna and Beloslav Lakes represent the largest inland water body along the Bulgarian coast. The shores of typical firth have been transformed into highly developed industrial areas. In another point of view, in the last 50 years, the bottom of lakes has been significantly anthropogenized. The Lack of regular monitoring of morphological changes and processes on the bottom does not allow a correct assessment of lakes' status. This work presents our initial activity to create a composite digital model of the Varna - Beloslav Lake complex, with a comprehensive analysis and identification of contemporary morphological bedforms. For creating a digital terrain model of the lakes, a geo based database was created with bathymetric surveys from different years and equipment, combined with high-resolution orthophoto mosaic of the shores. The data combine sonar mosaics, single beam, and multibeam bathymetric data, and UAV images. This provides accurate (vertical accuracy of less than 0.5% of water depth), full-bottom coverage of the bathymetric data allowing the generation of a digital model of the seafloor relief with a horizontal resolution of 3 m and creation a bathymetric map with an interval of 0.5 m. The lakes' bottom forms are divided into natural and anthropogenic types. The conducted morphometric analysis gave us reason to localize specific bedforms of a coastal sloop, slightly sloping accumulative bottom, lake plains, channels, and other features of anthropogenic nature.