- 18 May 2018
- 12:45 - 13:45
- Westvest 7, 2611 AX Delft The Netherlands
Dr. Carmelo Juez will talk about the hydraulic and geomorphological processes in riverbank lateral embayments. Such lateral embayments help in the promotion of morphological diversity of rivers, when a limited amount of fine sediments are trapped. A research study based on multiple laboratory tests, as well as numerical simulations, enabled the identification of the parameters that modulate the influence of river banks morphology in the transport of fine sediments.
River restoration works often include measures to promote morphological diversity and enhance habitat suitability. One of these measures is the creation of macro-roughness elements, such as lateral cavities and embayments, in the banks of channelized rivers. However, in flows that are heavily charged with fine sediments in suspension, such as glacier-fed streams and very low-gradient reaches of large catchment rivers, these lateral cavities may trap these sediments. Consequently, the morphological changes may be affected, and the functionality of the restoration interventions may be compromised. In this seminar, a research study will be presented that aimed at evaluating the influence of these bank lateral embayments on the transport of fine sediments in the main channel. Multiple laboratory tests with different geometrical configurations of lateral embayments were tested with uniform flow charged with sediments. Surface PIV, sediment samples and temporal turbidity records were collected all through the experiments. The results of these experiments led to identify the channel geometry and the shallowness of the flow as the governing parameters of the sediment trapping efficiency of the bank lateral embayments. Furthermore, the morphological resilience to flow fluctuations of the fine sediment deposits settled inside the bank lateral embayments was also assessed. It was observed that the morphological resilience of the sediment deposits is strongly dependent on the flow field and the mass exchange between the main channel and the lateral embayments. This mass exchange is modulated by the geometry of the cavities and the magnitude of the hydrographs applied. The presentation will conclude with a comparative study of the performance of two numerical schemes based on the Shallow Water Equations: a 1-st order numerical scheme and an arbitrary order WENO-ADER scheme. The results obtained indicate that the 1-st order numerical scheme fails in reproducing the complexity of the flow present in a channel with bank lateral embayments (vortex shedding, gravitational waves) even when refining the mesh. On the contrary, the high order numerical scheme can cope with such flow features and it can thus be an attractive solution for modelling environmental flows in such bank lateral embayments.
About the speaker
Dr. Carmelo Juez is currently a researcher at Ecole Polytechnique Federale de Lausanne (Switzerland). He graduated as Industrial Engineer at Universidad de Zaragoza (Spain) in 2010. Afterwards, he conducted a Master degree in Fluid Mechanics, focusing on computational fluid-dynamics techniques. In 2010, he joined the Computational Hydraulics Group at Universidad de Zaragoza and he worked in both research and consulting projects, as well as a software developer for geomorphological flows (sediment transport in fluvial environments and landslides in steep areas). Additionally, efficient computation with up-to-date techniques, such as OMP parallelization and GPU, were also considered during his work. Finally, he obtained his PhD degree at Universidad de Zaragoza in 2014 and he was a post-doctoral associate at the Universite Catholique de Louvain (Belgium) prior to moving to Lausanne in 2015. His research at Ecole Polytechnique Federale de Lausanne (Switzerland) has been focused on assessing the hydraulic and morphological impact of restoration activities in rivers (e.g. bank lateral embayments or sediment replenishment). More recently, he has diversified his research area by incorporating the study of urbanization processes at the river basin scale. Urbanization processes imply changes in the land use and ultimately, the alteration of the hydraulic and geomorphological properties of the river basin.