Complex hydro-morphological processes, such as erosion, transport, deposition or fan development, affect open water environments, including rivers, estuaries as well as lakes and reservoirs. As consequence many research tasks as well as practical applications rely on the correct prediction of these processes. Numerical models have become during the last decades a powerful tool in the research fields of hydraulic engineering and geosciences to simulate these hydro-morphological processes. With improved algorithms as well as an increasing computational power, it became feasible to simulate the interaction of water, sediments and air (multiphase flows) with high resolution in space and time. In addition, with an increasing quantity and quality of validation and verification data, both from laboratory experiments and field studies, numerical models become more accurate and it is possible to gain new insight in complex physical processes, e.g. dune development, river bed armoring or density driven transport. However, despite the increasing number of good examples on numerical modelling of sediment transport, there are still many open questions to be addressed (e.g. modelling of inhomogeneous bed material, role of turbulence in resuspension, simulation of bank erosion, complex free surface problems etc.).

The main goal of this session is to bring together scientists and engineers, which develop, improve, as well as apply numerical models for multiphase flows in open water environments. We invite contributions that deal with numerical modelling from small-scale, such as bed structure development, to large-scale interactions, such as long-term development of hydro-morphological processes in rivers, lakes, reservoirs and estuaries.

A special issue in the journal Earth Surface Processes and Landforms, composed by a selection of the abstracts from the 2017 and 2018 sessions, and with the preliminary title: “Measuring and numerical modelling of hydro-morphological processes in open-water environments” will be prepared.

Contributions may refer, but are not restricted, to:
• Entrainment processes of sediments (from cohesive sediments to armoured river beds)
• Bed load and suspended sediment transport processes (including flocculation processes)
• Processes in hydro-morphology, such as bed form development, grain size sortig, bed armour development, bank erosion, meandering migration or reservoir sedimentation
• Simulation of sediment management (in rivers, reservoirs, lakes and estuaries) including planning, operation and maintenance of hydro power plants
• Design and evaluation of restoration measures to revitalize rivers
• Navigation issues (in rivers and estuaries), such as sediment replenishment, dredging and erosion induced by ship generated waves
• Flood related issues such as an evaluation of the effects of long term morphological bed changes on flood security
• Eco-hydraulics such as flow – sediment – vegetation interaction
• Density driven transport in reservoirs, lakes and estuaries
• Critical discussion and information exchange on boundaries and limitations of the numerical modelling.