Assessment of Hydromorphological and Hydrodynamic Alterations Caused by Anthropogenic Interventions on the Riverbed. Case Study Danube Bala Branch New Bottom Sill

The necessity for navigation conditions improvement on the Lower Danube lead to the construction of a submerged bottom sill on the Bala branch. This paper presents differences that occurred between riverbed bathymetry and water current velocity values recorded in measurements campaigns using multibeam and ADCP techniques carried out before and after the bottom sill was built (June 2013 and March 2016). The comparative hydromorphological analysis showed the emergence of erosion areas up to -17.4 m and deposition areas up to 9.5 m. As for the hydrodynamic alterations, above the new built bottom sill, the water current velocity values of over 3.0 m/s were recorded.