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Improved structure of vertical flow velocity distribution in natural rivers based on mean vertical profile velocity and relative water depth

Song, Song and Schmalz, Britta and Fohrer, Nicola (2017):
Improved structure of vertical flow velocity distribution in natural rivers based on mean vertical profile velocity and relative water depth.
In: Hydrology Research, DOI: 10.2166/nh.2017.258, [Online-Edition: http://hr.iwaponline.com/content/early/2017/08/21/nh.2017.25...],
[Article]

Abstract

Logarithmic, power, and parabolic distribution laws were proven to be efficient for the prediction of vertical velocity distribution. Traditionally, the distribution formulas involve the friction velocity (u*) and the depth (y) of the measurement point. The low availability of friction velocity and limitation of real water depth data hindered the promotion and comparison of the available flow velocity formulas. In this paper, we proposed new formula structure adopting a relative flow velocity based on mean vertical velocity (u/ū) and dimensionless relative water depth (y/H). The observations showed that: 1) the substitution of u* and y with u/ū and y/H were reliable and applicable, and parabolic logarithmic and power fitting curves worked well, with an error of 7%, 10%, and 11%, respectively; 2) in water depth direction, the predicted results of the middle depth of the vertical profiles tend to be more reliable and precise. The highest estimated error appeared in the area near the water surface; 3) higher catchment slope resulted in larger coefficients and constants in logarithmic and power fitting; 4) in the rivers with higher width-to-depth ratio, the maximum profile velocity occurred closer to the water surface, and mean profile velocity tended to happened more at the bottom.

Item Type: Article
Erschienen: 2017
Creators: Song, Song and Schmalz, Britta and Fohrer, Nicola
Title: Improved structure of vertical flow velocity distribution in natural rivers based on mean vertical profile velocity and relative water depth
Language: English
Abstract:

Logarithmic, power, and parabolic distribution laws were proven to be efficient for the prediction of vertical velocity distribution. Traditionally, the distribution formulas involve the friction velocity (u*) and the depth (y) of the measurement point. The low availability of friction velocity and limitation of real water depth data hindered the promotion and comparison of the available flow velocity formulas. In this paper, we proposed new formula structure adopting a relative flow velocity based on mean vertical velocity (u/ū) and dimensionless relative water depth (y/H). The observations showed that: 1) the substitution of u* and y with u/ū and y/H were reliable and applicable, and parabolic logarithmic and power fitting curves worked well, with an error of 7%, 10%, and 11%, respectively; 2) in water depth direction, the predicted results of the middle depth of the vertical profiles tend to be more reliable and precise. The highest estimated error appeared in the area near the water surface; 3) higher catchment slope resulted in larger coefficients and constants in logarithmic and power fitting; 4) in the rivers with higher width-to-depth ratio, the maximum profile velocity occurred closer to the water surface, and mean profile velocity tended to happened more at the bottom.

Journal or Publication Title: Hydrology Research
Divisions: 13 Department of Civil and Environmental Engineering Sciences
13 Department of Civil and Environmental Engineering Sciences > Institute of Hydraulic and Water Resources Engineering
13 Department of Civil and Environmental Engineering Sciences > Institute of Hydraulic and Water Resources Engineering > Engineering Hydrology and Water Management
Date Deposited: 31 Jul 2018 06:45
DOI: 10.2166/nh.2017.258
Official URL: http://hr.iwaponline.com/content/early/2017/08/21/nh.2017.25...
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