Summary:

The article presents an assessment of the variability of riverbed sediment throughout the Przemsza river course and its main tributaries in relation with the observed disturbances of grain size changes caused by hydro-engineering activity in the channel. Sediment grain size composition in the river channel depends on the hydrodynamic balance and the water flow. In the stable river channel sediment grain size decreases regularly with the river course from the source to the mouth. In the channel where there are sections of anthropogenically modifications, the variation of sediment grain size composition may be irregular in the river course. The article presents the results of measurements and calculations which were made in the following gauging stations: Łysa Góra, Będzin, Sosnowiec, Jęzor, Chełmek non Przemsza river, in Golczowice, Okradzionów, Sławków, Maczki, Niwka on Biała Przemsza river and in Brynica, Kozłowa Góra (above the back of the reservoir Kozłowa Góra and downstream the dam), Szambelnia on Brynica river. The results of studies showes that variability of characteristic diameter of d10 is minimal, while the diameters of d50 and d90 is characterized by significant differences in all the tested gauging stations of Przemsza river and its tributaries. In Brynica river where Kozłowa Góra reservoir is located disturbances of natural process of grain size gradual decrease upstream and downstream the dam is observed. In the river course of Przemsza river and Biała Przemsza downstream their tributaries characteristic diameters of sediment have been increasing