Field-derived relationships for flow velocity and resistance in high-gradient streams

Francesco Comiti; Luca Mao; Andrew Wilcox; Ellen E. Wohl; Mario A. Lenzi

doi:10.1016/j.jhydrol.2007.03.021

Field-derived relationships for flow velocity and resistance in high-gradient streams

Francesco Comiti
, Luca Mao
, Andrew Wilcox
, Ellen E. Wohl
, Mario A. Lenzi

Geosciences

Research output: Contribution to journal › Article › peer-review

145 Scopus citations

Abstract

We measured velocity and channel geometry in 10 reaches (bed gradient = 0.08-0.21) of a predominantly step-pool channel, the Rio Cordon, Italy, over a range of discharges (3-80% of the bankfull discharge). The resulting data were used to compute flow resistance. At-a-station hydraulic geometry relations indicate that in most reaches, the exponent describing the rate of velocity increases with discharge was between 0.48 and 0.6, which is within the range of published values for pool-riffle channels. The Rio Cordon data are also combined with published hydraulics data from step-pool streams to explore non-dimensional relationships between velocity and flow resistance and factors including unit discharge, channel gradient, and step geometry. Multiple regression analysis of this combined field dataset indicated that dimensionless unit discharge (q^*) is the most important independent variable overall in explaining variations in velocity and flow resistance, followed by channel slope and the ratio of step height to step length. Empirical equations are provided both for dimensionless velocity and flow resistance, but prediction of the former variable appears more reliable.

Original language	English
Pages (from-to)	48-62
Number of pages	15
Journal	Journal of Hydrology
Volume	340
Issue number	1-2
DOIs	https://doi.org/10.1016/j.jhydrol.2007.03.021
State	Published - Jun 30 2007

Funding

Funding for this research was provided by the “Epic Force” Project EC Contract No. INCO-CT-2004-510735, from the MIUR Project PRIN 2004 No. 2004072251 “Opere di riqualificazione ambientale dei corsi d’acqua: dalla scala di laboratorio a quella di campo”, and from the University of Padova Project “Valutazione della pericolosità connessa a colate detritiche e trasporto solido su conoidi alpini”. Participation by Wohl and Wilcox was supported by NSF grant INT-0216951 and by a National Research Council Research Associateship Award to Wilcox. Our thanks to Prof. Robert Ferguson for having kindly provided his data, for an advance view of his paper, and for a thorough, very helpful pre-review of the manuscript. The reviewers of the manuscript are thanked for their comments that substantially improved the paper. The manuscript also benefited from reviews of an earlier version by Gregory Pasternack, John Jansen, and two anonymous reviewers.

Funders	Funder number
INT-0216951
National Research Council
European Commission	INCO-CT-2004-510735
2004072251

Keywords

Flow resistance
Mountain rivers
Salt tracers
Steep channels
Step-pool

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10.1016/j.jhydrol.2007.03.021

Cite this

@article{b8c8ad5a7d9346eea1a54d005c547eae,

title = "Field-derived relationships for flow velocity and resistance in high-gradient streams",

abstract = "We measured velocity and channel geometry in 10 reaches (bed gradient = 0.08-0.21) of a predominantly step-pool channel, the Rio Cordon, Italy, over a range of discharges (3-80\% of the bankfull discharge). The resulting data were used to compute flow resistance. At-a-station hydraulic geometry relations indicate that in most reaches, the exponent describing the rate of velocity increases with discharge was between 0.48 and 0.6, which is within the range of published values for pool-riffle channels. The Rio Cordon data are also combined with published hydraulics data from step-pool streams to explore non-dimensional relationships between velocity and flow resistance and factors including unit discharge, channel gradient, and step geometry. Multiple regression analysis of this combined field dataset indicated that dimensionless unit discharge (q*) is the most important independent variable overall in explaining variations in velocity and flow resistance, followed by channel slope and the ratio of step height to step length. Empirical equations are provided both for dimensionless velocity and flow resistance, but prediction of the former variable appears more reliable.",

keywords = "Flow resistance, Mountain rivers, Salt tracers, Steep channels, Step-pool",

author = "Francesco Comiti and Luca Mao and Andrew Wilcox and Wohl, \{Ellen E.\} and Lenzi, \{Mario A.\}",

note = "Funding Information: Funding for this research was provided by the “Epic Force” Project EC Contract No. INCO-CT-2004-510735, from the MIUR Project PRIN 2004 No. 2004072251 “Opere di riqualificazione ambientale dei corsi d{\textquoteright}acqua: dalla scala di laboratorio a quella di campo”, and from the University of Padova Project “Valutazione della pericolosit{\`a} connessa a colate detritiche e trasporto solido su conoidi alpini”. Participation by Wohl and Wilcox was supported by NSF grant INT-0216951 and by a National Research Council Research Associateship Award to Wilcox. Our thanks to Prof. Robert Ferguson for having kindly provided his data, for an advance view of his paper, and for a thorough, very helpful pre-review of the manuscript. The reviewers of the manuscript are thanked for their comments that substantially improved the paper. The manuscript also benefited from reviews of an earlier version by Gregory Pasternack, John Jansen, and two anonymous reviewers.",

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AU - Comiti, Francesco

AU - Mao, Luca

AU - Wilcox, Andrew

AU - Wohl, Ellen E.

AU - Lenzi, Mario A.

N1 - Funding Information: Funding for this research was provided by the “Epic Force” Project EC Contract No. INCO-CT-2004-510735, from the MIUR Project PRIN 2004 No. 2004072251 “Opere di riqualificazione ambientale dei corsi d’acqua: dalla scala di laboratorio a quella di campo”, and from the University of Padova Project “Valutazione della pericolosità connessa a colate detritiche e trasporto solido su conoidi alpini”. Participation by Wohl and Wilcox was supported by NSF grant INT-0216951 and by a National Research Council Research Associateship Award to Wilcox. Our thanks to Prof. Robert Ferguson for having kindly provided his data, for an advance view of his paper, and for a thorough, very helpful pre-review of the manuscript. The reviewers of the manuscript are thanked for their comments that substantially improved the paper. The manuscript also benefited from reviews of an earlier version by Gregory Pasternack, John Jansen, and two anonymous reviewers.

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N2 - We measured velocity and channel geometry in 10 reaches (bed gradient = 0.08-0.21) of a predominantly step-pool channel, the Rio Cordon, Italy, over a range of discharges (3-80% of the bankfull discharge). The resulting data were used to compute flow resistance. At-a-station hydraulic geometry relations indicate that in most reaches, the exponent describing the rate of velocity increases with discharge was between 0.48 and 0.6, which is within the range of published values for pool-riffle channels. The Rio Cordon data are also combined with published hydraulics data from step-pool streams to explore non-dimensional relationships between velocity and flow resistance and factors including unit discharge, channel gradient, and step geometry. Multiple regression analysis of this combined field dataset indicated that dimensionless unit discharge (q*) is the most important independent variable overall in explaining variations in velocity and flow resistance, followed by channel slope and the ratio of step height to step length. Empirical equations are provided both for dimensionless velocity and flow resistance, but prediction of the former variable appears more reliable.

AB - We measured velocity and channel geometry in 10 reaches (bed gradient = 0.08-0.21) of a predominantly step-pool channel, the Rio Cordon, Italy, over a range of discharges (3-80% of the bankfull discharge). The resulting data were used to compute flow resistance. At-a-station hydraulic geometry relations indicate that in most reaches, the exponent describing the rate of velocity increases with discharge was between 0.48 and 0.6, which is within the range of published values for pool-riffle channels. The Rio Cordon data are also combined with published hydraulics data from step-pool streams to explore non-dimensional relationships between velocity and flow resistance and factors including unit discharge, channel gradient, and step geometry. Multiple regression analysis of this combined field dataset indicated that dimensionless unit discharge (q*) is the most important independent variable overall in explaining variations in velocity and flow resistance, followed by channel slope and the ratio of step height to step length. Empirical equations are provided both for dimensionless velocity and flow resistance, but prediction of the former variable appears more reliable.

KW - Flow resistance

KW - Mountain rivers

KW - Salt tracers

KW - Steep channels

KW - Step-pool

UR - https://www.scopus.com/pages/publications/34249899091

U2 - 10.1016/j.jhydrol.2007.03.021

DO - 10.1016/j.jhydrol.2007.03.021

M3 - Article

AN - SCOPUS:34249899091

SN - 0022-1694

VL - 340

SP - 48

EP - 62

JO - Journal of Hydrology

JF - Journal of Hydrology

IS - 1-2

ER -

Field-derived relationships for flow velocity and resistance in high-gradient streams

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Keywords

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