Carpathian Journal of Earth and Environmental Sciences

The aim of the research presented in this paper was the recognition of potentials and drawbacks of visible light photos taken by the Sentinel-2 satellites as a source of data for hydrodynamic issues regarding dammed reservoirs located in the Polish Carpathian foothills. The authors analyzed the photos of five reservoirs: Goczałkowice, Tresna, Dobczyce, Czorsztyn and Solina. Depending on the object’s geographic location, one can expect one or two photos taken during each 5-day period. No more than 1/5 of the taken photos of the given locations contain a non-obscured view of the water bodies. Visibility varies throughout the year along with the expected clear sky percentage; and the probability of obtaining a clear picture is lower than this value. In the Polish Carpathians, the best visibility occurs in August, while the worst in December. The chance of getting a clear view is lower during high discharge periods than in low discharge ones. In the clear photos the authors identified density currents of different nature: turbidity, reverse turbidity (i.e. clear water entering a turbid area), eutrophic and thermal. The currents can also be seen as sub-glacial ones. The shapes of the visible currents can be used for calibration and validation of hydrodynamic numerical models of the reservoirs. The authors obtained a good accordance between the shapes of the currents visible on the photos and the water velocity field predicted by a numerical simulation with the FESWMS model for the hydrological and meteorological input variables set to follow the actual conditions that day.