River confluences play a very important role in river channel networks. They affect the drainage dynamics of a catchment, the sediment transport through the river channel network and mixing processes in rivers. River confluences are characterised by a strong interaction between converging flows on the one hand, and their interaction with the riverbed bed on the other. These interactions result in enhanced turbulence at the confluence, development of complex, 3D flow patterns and characteristic morphological features in the riverbed, and may affect bank stability.

The influence of different morphological elements in the riverbed on the 3D flow structure and its turbulence characteristics is still not fully understood, neither is the mechanism by which the generated turbulence affects sediment movement and morphological changes of the riverbed. The interest in studying different aspects of river confluence hydrodynamics and morphodynamics is constantly increasing and we feel that the knowledge about river confluences would benefit if researchers are joined in a network.

The main goal of this session is to bring together experimentalists, field researchers and numerical modelers with an expertise in open-channel hydraulics, turbulence measurement and modelling, measurement instrumentation and techniques, sediment mechanics and river morphology. Specific topics of interest could include, but are not limited to: the influence of different controls such as the planform geometry, the junction angle, the extent of bed elevation discordance, the momentum-flux ratio of the combining flows and the width-ratio of the combining channels on the 3D flow hydrodynamics in river confluences, hydrodynamic processes, structure of turbulent flow, characteristics of the mixing layer, as well as the influence of sediment size and transport rate on the development of avalanche faces and separation zone bars, and the bed erosion mechanism.