Braided River Morphodynamics "Morpho"

The major aim and outcome of this projects is the enhencement of the ability of river engineers and ecologists to manage the gravel and water resources, erosion and sedimentation problems and ecosystem of dynamic, braided gravel-bed rivers and the impact of changes in the flow regime and sediment supply by identifying the spatial and temporal characteristics of braided river morphology, morphologic change, eroding bank lines, channel pattern, hydraulic parameters and sediment transport "events" in relation to water discharge and sediment supply. In Austria high precipitation rates and the Alpine environment with steep gradients and large sediment production were the reasons for the mostly historical existance of braided river sections, interrupted by straight and meandering channels. Today river regulations, the erection of water power plants, modifications in land use and climatic changes result in either surplus of sediments in impounded sections and reservoirs or a lack of material in remaining free flowing sections (Danube, Drau, Mur, Salzach etc.), leading to river bed degradation problems. Negative technical (failure of bank protection measures) and ecological (lack of dynamic gravel bars, lowering of the groundwater table) consequences have been related to the degradation and up to now research showed that to a large extent the increase of the river bed width could solve the problem. The increase of the width leads to morphological dynamics and a braided pattern for which insufficient observation and simulation means exist at the moment. The most comparable unaffected braided rivers occur in New Zealand, where this project will be conducted. Field studies at braided rivers in New Zealand are used to improve the measurement and modelling approaches, which will be applied in Austria for further research as well as practical management questions.