Turbulent flow structure at a discordant river confluence: Asymmetric jet dynamics with implications for channel morphology

Alexander N. Sukhodolov, Julian Krick, Tatiana A. Sukhodolova, Zhengyang Cheng, Bruce L. Rhoads, George S. Constantinescu

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Pages (from-to)1278-1293
Number of pages16
JournalJournal of Geophysical Research: Earth Surface
Volume122
Issue number6
DOIs
StatePublished - Jun 1 2017

Keywords

  • depositional wedge
  • discordant channel
  • field research
  • river confluence
  • scour
  • turbulent jet

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

Fingerprint Dive into the research topics of 'Turbulent flow structure at a discordant river confluence: Asymmetric jet dynamics with implications for channel morphology'. Together they form a unique fingerprint.

  • Cite this