Summary:

The Upper Odra valley on sector between Chałupki (km 20,0) and Olza mouth (km 28,0) is subject of deformations caused by natural factors and by human activity. This sector constitutes the border river between Poland and Czech Republic. Seven unique meanders exist here. The I-st and the IV-th meander have been broken during the floods in 1997 and 1967. Together with road bridge (km 20,530) they constitute three critical places with regard to flow capacity of Odra valley in its upper course. The problem of the border between both states Poland and Chech Republic on this sector is still not solved, what causes serious lawful and economic complications. The studied sector is distinguished by intensive bank erosion and sedimentation. The dynamic of Odra morphological processes is high here, so changes of water course as well as shape of the riverbed are very indicative. At present, the new channels formed within the meanders I i IV are characterized by the rapid flow caused by the high bed slope. From the authors’ studies it follows, that the old river branches permit to pass only a small percentage of the average discharge. Great outwashes, islands and dense vegetation within the meanders cause a very high variation of flow resistance and flow capacity of the Odra River valley within the investigated area.