A stretch of the Odra river between km 20.7 (Chałupki gauging section) and km 27.7 (Olza river mouth) is subject to natural morphological processes and has 7 natural meanders. Some of the factors causing the morphological changes in this meandering river stretch include the transport and sedimentation of bed-load and suspended load. The extent and rate of those changes depend on the intensity and scale of hydrological events. The course of such changes could be easily observed after extreme floods when mass transport of sediment occurs. For example, the sediment mass transport as a consequence of the 1997 flood resulted in a change of the Odra river channel in the area of meander I (break of the meander and shortening of the river course) and the development of sediment islands in the cut-off old arm. The substructure of the islands consist of bed-load (stones, boulders, gravel and coarse sand), and the superstructure is built of fine-grained sediments (silt, clay) containing organic matter. Using the available hydrological data, the authors tentatively estimated the suspended load transport in the Chałupki gauging section and determined the amount of suspended load settled in the upper layer of the island in the area of the broken meander. The settled fine-grained organic mud has cohesive properties which are important for stabilisation of new islands and for development of pioneering vegetation.

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