TY - JOUR
T1 - Turbulent flow structure at a discordant river confluence
T2 - Asymmetric jet dynamics with implications for channel morphology
AU - Sukhodolov, Alexander N.
AU - Krick, Julian
AU - Sukhodolova, Tatiana A.
AU - Cheng, Zhengyang
AU - Rhoads, Bruce L.
AU - Constantinescu, George S.
N1 - Funding Information:
This research was financially supported by the grants SU 405/4-1 and SU 405/7-1 from the Deutsche Forschungsgemainschaft (D.F.G.). Anna Sukhodolova is thanked for the help with the field measurements and data processing. Two anonymous reviewers provided thorough comments and suggestions that helped in improving the presentation of the results. The work of B. Rhoads, Z. Cheng, and G. Constantinescu was partially supported by the BCS Geography and Spatial Sciences Program of the US National Science Foundation under grants 1359911 and 1359836. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the US National Science Foundation and the Deutsche Forschungsgemainschaft. A reader interested in further communication about this study and data can contact the authors by using the following address: alex@igb-berlin.de.
Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.
PY - 2017/6/1
Y1 - 2017/6/1
N2 - Only a handful of field studies have examined turbulent flow structure at discordant confluences; the dynamics of flow at such confluences have mainly been examined in the laboratory. This paper reports results of a field-based investigation of turbulent flow structure at a discordant river confluence. These results support the hypothesis that flow at a discordant alluvial confluence with a velocity ratio greater than 2 exhibits jet-like characteristics. Scaling analysis shows that the dynamics of the jet core are quite similar to those of free jets but that the complex structure of flow at the confluence imposes strong effects that can locally suppress or enhance the spreading rate of the jet. This jet-like behavior of the flow has important implications for morphodynamic processes at these types of confluences. The highly energetic core of the jet at this discordant confluence is displaced away from the riverbed, thereby inhibiting scour; however, helical motion develops adjacent to the jet, particularly at high flows, which may promote scour. Numerical experiments demonstrate that the presence or absence of a depositional wedge at the mouth of the tributary can strongly influence detachment of the jet from the bed and the angle of the jet within the confluence.
AB - Only a handful of field studies have examined turbulent flow structure at discordant confluences; the dynamics of flow at such confluences have mainly been examined in the laboratory. This paper reports results of a field-based investigation of turbulent flow structure at a discordant river confluence. These results support the hypothesis that flow at a discordant alluvial confluence with a velocity ratio greater than 2 exhibits jet-like characteristics. Scaling analysis shows that the dynamics of the jet core are quite similar to those of free jets but that the complex structure of flow at the confluence imposes strong effects that can locally suppress or enhance the spreading rate of the jet. This jet-like behavior of the flow has important implications for morphodynamic processes at these types of confluences. The highly energetic core of the jet at this discordant confluence is displaced away from the riverbed, thereby inhibiting scour; however, helical motion develops adjacent to the jet, particularly at high flows, which may promote scour. Numerical experiments demonstrate that the presence or absence of a depositional wedge at the mouth of the tributary can strongly influence detachment of the jet from the bed and the angle of the jet within the confluence.
KW - depositional wedge
KW - discordant channel
KW - field research
KW - river confluence
KW - scour
KW - turbulent jet
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U2 - 10.1002/2016JF004126
DO - 10.1002/2016JF004126
M3 - Article
AN - SCOPUS:85021356216
VL - 122
SP - 1278
EP - 1293
JO - Journal of Geophysical Research: Earth Surface
JF - Journal of Geophysical Research: Earth Surface
SN - 2169-9003
IS - 6
ER -