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 ...
The analysis of variability of riverbed elevation recorded at five selected gauging cross-sections of Nida River, and at three gauging stations of Czarna Nida is presented in the paper. The studies concern the period of 60 - 80 years of observation. The trends of riverbed changes during the study period at the selected gauging stations were calculated based on the variability of observed minimal annual water stages. The reasons for the observed changes in the river course and channel geometry are given. These changes were caused by river regulation consisted of the shortening and narrowing of the river channel. Moreover, grain size distribution analysis in the selected gauging stations of Nida River and characteristic diameter variability of sediments along the river course examination are presented. These analyses were to evaluate the variability of characteristic diameters along the river course in connection with observed changes in cross-sections' geometry. Additionally, to confirm the process of erosion or deposition recognized in the examined river channels, hydrodynamic equilibrium was determined. Three methods were proposed and used: the mean velocity and critical velocity in the main river channel comparison, the stream power value calculation which defines the character of the river channel, and the WWK ...
