River morphodynamics and its mathematical modelling

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This research program combines the theoretical and experimental research of mechanisms of flow and sediment transport involved in the deformation of bed and banks of alluvial streams with the development of physically-based, high-accuracy numerical models for the simulation and prediction of river morphological changes. These changes may occur naturally or as a response to direct or indirect human river interventions. The research focuses on: 1- large-scale turbulence coherent structures and their morphological consequences; and 2- bed morphological changes and bank migration in meandering streams.       An extensive series of experiments will be carried out in a 20m-long straight channel having an adjustable width from 1m to 2m. In these experiments, events of generation, growth and decay of large-scale coherent structures and their morphological consequences will be recorded. This study is expected to yield a better understanding of the development of large-scale bed forms (alternate and multiple bars) and the development of incipient stream deviations from straight alignment eventually leading to meandering or braiding. It will also constitute a foundation for the future modelling of these processes.       Additionally, the mechanisms of flow and sediment transport involved in bed and bank deformation in meandering streams will be investigated. For this purpose, initial (non-equilibrium) laboratory meandering streams lying on a 21m-long, 7m-wide sand basin, will be subjected to a variety of flow conditions and their time-evolution will be monitored. The new data and insights will be used to develop two numerical models:(i) a 3-D based model for the computation of meandering bed topography and its time-evolution; and (ii) a model for the simulation of the long-term planimetric evolution of meanders and prediction of meander migration rates. These models are expected to constitute valuable tools to assess the impact on the physical environment of both natural and man-induced meandering morphological changes.       This research program will result in the training of 3 Ph.D. Students, 3 M.Sc. students and 1 B.Sc student.