We presented results of our research on the 6th International Conference on Water Resources and Environment Research in Koblenz, Germany. The basis task of this conference is overviews on fundamental issues in environmental hydrological problematics of streams in the world. Especially, climate influence of rivers, problematic of sediment processes and polutants of sediments and water in river systems, hydrological modelling and monitoring and problematic of water management linked with contemporary environmental demands are the main focuses of this congress.
High water stage (water stage about 650-700 cm) of the Rhein River in Koblenz (state at 5 p.m., 3rd of June 2013, photo by Galia T.)
Fountain which represents historical flood water stage on the right bank of the Rhein River in Koblenz (photo by Skarpich V.)
We participated on sessions:
UNDERSTANDING SEDIMENT PROCESSES AT CATCHMENT SCALE (session moderate by Peter Heininger)
Modelling of potential bedload transport: identification instrument of erosion and accumulation
Škarpich, V., Hradecký, J., Galia, T.
Abstract: Our paper summarizes the results of bedload transport modelling in the Morávka River, Ostravice River and Bečva River basins, conducted with the use the BAGS (Bedload Assessment for Gravelbed Streams) spreadsheet-based program. The presented results show potential rates of bedload transport linked with identification of erosion and accumulation processes in channels. Selected channel cross-sections include preserved gravel-bed reaches with anabranching development as well as transformed reaches with accelerated deep erosion and occurrence of a single bedrock channel. The modelling shows bed load transport trends in relation with the morphology of the channel. Presented results show a potential rate of bed load transport because sediment inputs and barriers were not included in the model. In fact, these results of potential rates of bed load transport can be use for distinguishing of the reaches with erosion or accumulation trends. The modelling on cross-sections with a low rate of fluvial erosion (anabranching channel pattern) shows the decrease in potential bed load transport. It is caused by increasing or decreasing of (dis)connectivity in longitudinal direction of the fluvial (dis)continuum system. It is affected by diversion of flow through sub-channels and decrease in transport capacity. We define this area of active channel as a zone of reduced growth in transport capacity. In contrast, reaches with single channel pattern show higher values of the potential bed load transport caused by absence of this zone of reduced growth in transport capacity. The results may be applied in order as a conceptual scheme to improve the management of the local watersheds.
MODERN HYDRAULIC STRUCTURES FOR BETTER HYDRODYNAMICS AND HYDROMORPHOLOGY OF STREAMS AND RIVERS (session moderate by Arthur Radecki-Pawlik)
Sediment transport in headwater streams of the Carpathian Flysch belt: its nature and recent effects of human interventions
Galia, T., Hradecký, J.
Abstract: As proved our recent research in Beskydian headwater channels, obtained critical values (bed shear stress, unit stream power and unit discharge) for beginning of bedload transport of certain grain diameters were significantly lower than those coming from Alpine and Andine environments. On the other hand, local flysch-based mid-mountain streams contain generally finer sediments when compared to other regions. Simulation of bedload transport in one-dimensional TOMSED model also pointed up on relatively small total amounts of material which can be potentially transported during a single flood event. This fact resulted from supply-limited character of most of local streams with relation to often occurrence of bedrock outcrops in channels. Together with changes in land-use represented by afforestation since the end of 19th century, systematical cleaning of channels from woody debris by local forest management and building of check-dam structures, accelerated incision trends are observed in most of local torrents. One must note, that flysch bedrock structure (alternation of sandstones and claystones) is less geomorphic resistant and more prone to incision and slope deformations than other solid rocks. Thus, check-dam constructions should be viewed as negative interventions in to the local channel segments due to strictly supply-limited conditions in most local basins and predisposition to quick incision in to weak rocks. Also, removing of large woody debris accelerate incision processes expect its function as a significant element of biodiversity in channel. By contrast, many roads cross local headwater streams by under-dimensioned sluices. These sluices acting as a barrier since sediments clogged up inside during some higher magnitude flood events, resulting to accelerated incision trends under these constructions. Extracting of deposited gravels and boulders from upstream segment comes after a flood event. Unfortunately, it is no surprising fact that extracted material captured by sluices or check-dams is not returned in to the channel segment.
Report in czech language on the website of the Department of Physical Geography and Geoecology, University of Ostrava: here