Flow Characteristics over a Gravel Bedform: Kaj River Case Study

Maddahi, Mohammad Reza; Afzalimehr, Hossein; Rowiński, Paweł M.

doi:10.1515/acgeo-2016-0079

Cited by 15 publications

(5 citation statements)

References 32 publications

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“…In fact, a linear distribution of Reynolds stress had already been reported by Graf and Altinakar (1998), but over fixed gravel-bed channels. Maddahi et al (2016) investigated flow characteristics over a gravel bed in a river and found more complicated patterns regarding the Reynolds stress and turbulence intensity distributions.…”

Section: Introductionmentioning

confidence: 99%

Non-uniform flow over cobble bed with submerged vegetation strip

Afzalimehr

Barahimi

Sui

2019

Proceedings of the Institution of Civil Engineers - Water Manag

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2 3To better understand the influence of non-uniform flow in coarse-bed streams with a submerged vegetation strip on flow characteristics, data were collected from experiments in a laboratory flume and field investigations in a cobblebed river reach in central Iran. The results of the experiments and field observations showed that the velocity profiles for non-uniform flows in cobble-bed streams with vegetation strips can be divided into either two or three sub-zones. The velocity profiles of non-uniform flows in the laboratory flume and cobble-bed stream deviated from the log law in the wake and mixing zones, but fitted approximately in the log-law layer zone. The distribution of Reynolds stress for non-uniform flows was influenced by the vegetation strip and showed a non-concave shape. Near the channel bed, sweep motion occurred more frequently than the ejection process. Close to the top of vegetation strip, the correlation coefficient (r u 0 w 0 ) was negative, indicating downward momentum transport due to sweep and ejection processes. However, r u 0 w 0 was positive near the water surface, indicating upward momentum by the vegetation strip due to inward and outward interactions. The study shows that laboratory results cannot be easily applied to natural rivers without considerable assumptions.

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Section: Introductionmentioning

confidence: 99%

Non-uniform flow over cobble bed with submerged vegetation strip

Afzalimehr

Barahimi

Sui

2019

Proceedings of the Institution of Civil Engineers - Water Manag

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“…The favorable pressure gradient (FPG) flow, in which the depth of flow decreases and velocity increases in the flow direction, has been reviewed frequently [1][2][3][4][5][6][7][8][9]. Studies in open channels with bare banks and coarse-bed indicate that the favorable pressure gradient flow suppresses the generation of turbulence [9].…”

Section: Introductionmentioning

confidence: 99%

Effect of submerged vegetation density on flow under favorable pressure gradient

Brahimi

Afzalimehr

2018

SN Appl. Sci.

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“…Flow regime and structure have been studied by a number of researchers [31]. Sindelar and Smart (2016) argued that ow regime was related to the mean value of the Froude Number in a step-pool reach, while Maddahi et al (2016) studied the e ect of bed form variations on the ow structure [32,33].…”

Section: Introductionmentioning

confidence: 99%

Field Study of Flow Resistance in Step-pool Streams (Case study of Dizin River)

2018

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A series of steps and pools are ubiquitous bed forms in mountain stream channels, occurring where gradients exceed 2% and materials are in the gravel to boulder size range. Flow resistance, re ected by roughness elements, appears to be an important controlling factor in bed load transport rates and mean ow velocity. To estimate ow resistance, some morphological features and velocity were measured in the step-pool channel of Dizin River, located in Karaj River watershed in Iran. Topographic surveys and bed sediment sampling were made in a low-ow condition, while three-dimensional velocity measurements were made in low, medium, and high ow conditions. Gradient variations are in the range of 7% to 14%. As ow resistance is a function of geometry, bed material size, longitudinal slope, and hydraulic radius, dimensional analysis was conducted to develop a non-dimensional relationship for ow resistance in step-pool reaches. Thereafter, it was calibrated for the measured dataset of Dizin river and validated for Rio Cordon dataset. Comparable results of validation with a river located in a di erent environment suggest that ow resistance features in semi-arid and humid streams may have similar e ects on a non-dimensional resistance coe cient.

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Flow Characteristics over a Gravel Bedform: Kaj River Case Study

Cited by 15 publications

References 32 publications

Non-uniform flow over cobble bed with submerged vegetation strip

Non-uniform flow over cobble bed with submerged vegetation strip

Effect of submerged vegetation density on flow under favorable pressure gradient

Field Study of Flow Resistance in Step-pool Streams (Case study of Dizin River)

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