Verification of a novel bed load transport calculation method for river regulation design case study
Abstract
The reliable sediment transport calculation is still a challenge, especially in the case of spatially and temporally varying river reaches. Therefore, more and more sediment transport models are being made and published recommended for complex morphodynamic circumstances. In 2017, Török et. al presented a novel approach. As opposed to previous models it suggests not to develop a new model, but to apply the existing models combined, complementing each other's weaknesses.
The critical point of the procedure is the precise definition of the applicability limits of the sediment transport models. This is most often described as a function of particle size. For instance, the van Rijn (1984) model is recommended to apply for sand (d < 2 mm), while other models (e.g. Wilcock and Crowe, 2003) for coarser gravels. However, a recent study says (Török et. al, 2019) that the grain size itself is not a reliable indicator for the application limits. However, the shear Reynolds number (Re*) is a proper variable for that reason (van Rijn model: Re* < 300; Wilcock and Crowe: Re* > 400). The novel method was established by the combination of the van Rijn and Wilcock and Crowe model and validated with laboratory and field data (Török et. al, 2018). In this study, the advantage of the approach was studied within a river regulation design project. It was crucial to determine what kind of bed changes are resulted by various interventions (mainly building, alteration or demolishing groins). The results represent that the bed changes calculated by the novel method are more reliable and are in the realistic order of magnitude. In contrast, the van Rijn model overestimates the bed changes especially at the tip of the groins and in the armored main stream, while the Wilcock and Crowe model underestimates the erosion of the fine sediments e.g. in the groin fields. According to the results the combined approach can significantly support the river regulation design. Especially in river sections where the complex flow and morphological features result in varied bed material, the combined method calculates more precisely the expected effects of the interventions than one sediment transport model singly. Summarizing, this study highlights that the combined use of sediment transport models is a promising alternative in the sediment transport calculation.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP42B..08T
- Keywords:
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- 1824 Geomorphology: general;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 1830 Groundwater/surface water interaction;
- HYDROLOGY;
- 1856 River channels;
- HYDROLOGY