Summary:

The main goal of the presented research was to determine the morphological changes in the "regulated" section of the Czarna Nida River caused by four freshets. The surveying measurements of twelve cross-sections, bed material composition and stream velocity were carried out. The changes of the hydrodynamic conditions, having a decisive impact on the intensity of transported material, bank erosion and thus on the channel shape were estimated. The volume of material accumulated within the channel and flood plains and derived from bank erosion was estimated. The Ackers and White- equation was used to calculate the volume of transported material. It was found that the greatest impact on the river channel transformation has the deposition of material.