ABSTRACT
Quantitative and qualitative data on channel changes along the lower Vistula (Poland) arising from regulation works carried out in the 19th and 20th centuries and single dam construction in 1968. The lower Vistula currently does not comprise a homogeneous fluvial system. Due to human activity channel lacks its typological continuity − as a result of existing of a dam and channel regulation devices. Changes of the bed load balance are characterized in the segment from Kepa Polska to Baltic Sea during the last 180 years are discussed. Conducted research on different channel reaches (unregulated channel, strong transformation channel below dam and regulated reach) allowed to get to know different conditions of bed load transport in terms of its size, type of material and mode of transport. Studies showed that each increase in flows corresponds to a proportional increase in the mesoforms dynamics. The size of bedload movement was determined based on the dynamics of bars, their movement rate and the layer thickness of these forms. Studies showed that bedload in the unregulated section on average amounted to nearly 2.2 million tons per year, whereas in the regulated section it did not exceed 1.0 million tons per year.
