Hydraulic resistance in mixed bedrock-alluvial meandering channels

Vitale, Alejandro J.; García, Marcelo H.; Fernández, Roberto; Vitale, Alejandro; Parker, Gary; Garcia, Marcelo

Abstract

We present an experimental analysis of hydraulic roughness variations due to changes in alluvial cover in a mixed bedrock-alluvial meandering channel with larger bedrock roughness than alluvial roughness. Three sets of experiments were conducted in a highly sinuous flume: one with bare bedrock, and two with enough sediment to cover 21% and 78% of the bedrock respectively. We compare our results with data from experiments previously conducted in the same flume with flat-and smooth-bed, and data from experiments with fully alluvial conditions. Our results show that: (i) hydraulic resistance in a mixed bedrock-alluvial channel changes with the degree of alluviation; (ii) hydraulic resistance is greater for bare-bedrock conditions, and decreases as sediment supply increases; (iii) if bedforms appear, hydraulic resistance may be larger than of bare bedrock conditions due to form drag; (iv) fluctuations in alluvial cover due to freely-migrating bars lead to instantaneous changes in hydraulic resistance.

Citation

Vitale, A. J., García, M. H., Fernández, R., Vitale, A., Parker, G., & Garcia, M. (2020). Hydraulic resistance in mixed bedrock-alluvial meandering channels. Journal of Hydraulic Research, 59(2), 298-313. https://doi.org/10.1080/00221686.2020.1780489

• Journal Article Type: Article
• Acceptance Date: Dec 30, 2019
• Online Publication Date: Aug 18, 2020
• Publication Date: 2020
• Deposit Date: Apr 3, 2020
• Publicly Available Date: Aug 19, 2021
• Journal: Journal of Hydraulic Research
• Print ISSN: 0022-1686
• Publisher: Taylor and Francis
• Peer Reviewed: Peer Reviewed
• Volume: 59
• Issue: 2
• Pages: 298-313
• DOI: https://doi.org/10.1080/00221686.2020.1780489
• Keywords: Alluvial cover; Bars; Bed roughness; Bedforms; Bedload; Hydraulic resistance; Meandering
• Public URL: https://hull-repository.worktribe.com/output/3487532
• Publisher URL: https://www.tandfonline.com/doi/abs/10.1080/00221686.2020.1780489?journalCode=tjhr20