Instream wood, channel morphology, sediments, organic matter, Odra River

It is widely known that instream wood plays an important role in forested river basins. In general, instream wood influences flow hydraulics, sedimentation patterns, and channel morphology. Although instream wood positively affects a wide range of stream parameters, especially morphological and hydraulic diversity, it is still the subject of disputes between river managers and environmentalists. Of course, the river manager must remove some pieces of instream wood to avoid, for example, damaging the bridge structure. On the other hand, in places where structures of instream wood do not threaten any legitimate interests and pose no reasonable risk, they should be left. The presence of wood in streams is helpful to achieve a good ecological status of the river, which is one of the most important requirements of the Water Framework Directive. So it would be beneficial to find a compromise between flood protection and good hydromorphological quality. This study deals with the complex assessment of instream wood on channel morphology and sediment parameters including the content of organic matter at the spatially detailed scale of a selected bend of the Odra River. This area of interests is located between municipalities Kunín and Suchdol nad Odrou and it is a part of PLA Poodří. Within the study area (66.5 river km), 12 instream wood pieces were identified (length ≥ 1 m, diameter ≥ 10 cm). These structures significantly affected channel morphology, because they were the main initiators of pools formation. In total, 28 samples of surface bed sediments were collected from various locations (from the channel bed, bars, and lateral disconnected pool).