Evaluation of aDcp processing options for secondary flow identification at river junctions

Détails

Ressource 1Télécharger: Moradi_et_al_2019.pdf (50733.12 [Ko])
Etat: Public
Version: Author's accepted manuscript
Licence: Non spécifiée
ID Serval
serval:BIB_67F1A1A8F840
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Evaluation of aDcp processing options for secondary flow identification at river junctions
Périodique
Earth Surface Processes and Landforms
Auteur(s)
Moradi Gelare, Vermeulen Bart, Rennie Colin D., Cardot Romain, Lane Stuart N.
ISSN
0197-9337
1096-9837
Statut éditorial
Publié
Date de publication
13/10/2019
Peer-reviewed
Oui
Langue
anglais
Notes
A freely available read only version can be obtained at :
https://rdcu.be/bVZNP

Résumé
Secondary circulation in river confluences results in a spatial and temporal variation of fluid motion and a relatively high level of morphodynamic change. Acoustic Doppler current profiler (aDcp) vessel-mounted flow measurements are now commonly used to quantify such circulation in shallow water fluvial environments. It is well established that such quantification using vessel-mounted aDcps requires repeated survey of the same cross-section. However, less attention has been given to how to process these data. Most aDcp data processing techniques make the assumption of homogeneity between the measured radial components of velocity. As acoustic beams diverge with distance from the aDcp probe, the volume of the flow that must be assumed to be homogeneous between the beams increases. In the presence of secondary circulation cells, and where there are strong rates of shear in the flow, the homogeneity assumption may not apply, especially deeper in the water column and close to the bed. To reduce dependence on this assumption, we apply a newly-established method to aDcp data obtained for two medium-sized (~60-80 m wide) gravel-bed river confluences and compare the results with those from more conventional data processing approaches. The comparsion confirms that in the presence of strong shear our method produces different results to more conventional approaches. In the absence of a third set of fully independent data, we cannot demonstrate conclusively which method is best, but our method involves less averaging and so in the presence of strong shear is likely to be more reliable. We conclude that it is wise to apply both our method and more conventional methods to identify where data analysis might be impacted upon by strong shear and where inferences of secondary circulation may need to be made more cautiously.
Mots-clé
Earth-Surface Processes, Earth and Planetary Sciences (miscellaneous), Geography, Planning and Development
Web of science
Open Access
Oui
Financement(s)
Fonds national suisse / Projets / 200021_160020
Création de la notice
05/11/2019 15:56
Dernière modification de la notice
06/11/2019 7:08
Données d'usage