SEDIMENT SORTING AS RESULT OF RIVER BED EROSION

摘要

In the paper riverbed degradation downstream a hydraulic structure is discussed. As thernmajor issue is considered sediment sorting which occurs during this process. Sedimentrnsorting is obtained by computation by of sediment transport by size fractions with thernuse of sediment transport formula specially worked out for Carpathian rivers. The ARrnformula was prepared for a sediment mixture with taking into account a possibility ofrnblocking in grains. The existence of armour coat and its removal by flood waves isrnincluded into computation. The method is tested on a case of riverbed erosionrndownstream Dobczyce Dam on Raba River. The computations are done for simplifiedrnprismatic channel and for natural cross-sections and longitudinal profile. The resultsrnshowed the importance of sediment sorting – the significant changes of sedimentrndistribution curves were observed. Therefore the influence of sediment sorting isrnimportant for the riverbed degradation.