Hydraulic analysis of a meander on the Danube River using a 2D flow model.

This paper presents the development, calibration and verification of a two-dimensional model for a Danube reach and its old cutoff meander. The considered meander was at one point separated from the main reach with a levee, which caused a series of unwanted environmental consequences. Aiming to stop the ongoing degradation of the meander, the validated model was engaged to investigate the effects different river works would have on its current state. The considered river works involved dredging in certain parts of the meander, while keeping in mind the negative effects these works can have on the environment, as well as possible widening of the existing opening in the levee. Numerical simulations showed that all the considered scenarios would result in a general increase of velocities, which is important from the aspect of sediment deposition. After a thorough evaluation of the results, it was found that by carefully selecting the locations where dredging should be conducted, no other interference is needed to put an end to the increasingly deteriorating situation in the meander. Computations confirmed that the suggested river works would increase the unit discharge in the entire meander, especially in its upstream part. The redistribution of flow around the island downstream of the levee (that formed during past years as a result of sediment deposition) was also predicted, where the flow would once again favor the left side of the island. This is a more natural path of flow that would aid the flushing of previously deposited sediment in this part of the meander.