Macro-turbulent flow and its impacts on sediment transport potential of a subarctic river during ice-covered and open-channel conditions

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Lotsari, E.; Dietze, M.; Kämäri, M.; Alho, P.; Kasvi, E. Macro-Turbulent Flow and Its Impacts on Sediment Transport Potential of a Subarctic River during Ice-Covered and Open-Channel Conditions. Water 2020, 12, 1874. https://doi.org/10.3390/w12071874

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Title: Macro-turbulent flow and its impacts on sediment transport potential of a subarctic river during ice-covered and open-channel conditions
Author: Lotsari, Eliisa; Dietze, Michael; Kämäri, Maria; Alho, Petteri; Kasvi, Elina
Publisher: MDPI
Date: 2020
Language: en
Belongs to series: Water 12 7 (2020)
ISSN: 2073-4441
DOI: https://doi.org/10.3390/w12071874
URI: http://hdl.handle.net/10138/335637
Abstract: Macro-turbulent flows (i.e., coherent flow structures reaching through the whole water column), have not been studied widely in northern seasonally frozen rivers during both open-channel and ice-covered flow conditions. Thus, we aim: (1) to detect and compare the macro-turbulent flow, both at open-channel and ice-covered flow conditions; (2) to explore spatial variation of macro-turbulent flow characteristics within a meander bend; and (3) to detect the effects of near-bed layer velocity fluctuation on bedload transport during differing overall flow conditions. The analyses are based on 5–10 min-long acoustic Doppler current profiler (ADCP) measurements from a subarctic river. The ice-covered low flow, and open-channel higher and lower flow conditions were measured over the period of 2016 to 2020. This study found that macro-turbulent flow existed at all measurement locations under both open-channel and ice-covered flow conditions. Macro-turbulent flow was most consistent and obvious in the streamwise velocity component, and in particular at the inlet and outlet of the investigated meander bend. During all seasons, the near-bed velocities consistently exceeded the sufficient amount for sediment transport. At inlet and outlet areas, the greatest near-bed velocity fluctuation across the critical threshold for sediment transport coincided with the measurement times having frequent macro-turbulent flow.
Subject: subarctic
velocity
adcp
ice-covered flow
macro-turbulence
cluster analysis
open-channel flow
macro-turbulent flow
sediment
subarctic river
ice-covered
open-channel
water
ice
flow
water flow
seasons
impacts
2016-2020
Subject (ysa): subarktinen
nopeus
jääpeitteinen virtaus
makroturbulenssi
klusterianalyysi
avoimen kanavan virtaus
sedimentit
joet
vesi
jää
virtaus
veden virtaus
vuodenajat
vaikutus
vaikutukset
Rights: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).


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