Local scouring around L-head groynes

Dehghani, Amir Ahmad; Azamathulla, Hazi Mohammad; Najafi, Saeed; Ayyoubzadeh, Seyed Ali

doi:10.1016/j.jhydrol.2013.09.020

Cited by 34 publications

(7 citation statements)

References 12 publications

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“…Moreover, bed shear stress occurred in the scour hole rose or was stable with time. Dehghani et al (2013) compared scoured depth between single laboratory L-head groin and straight groin. In this study, scour depth influenced by L-head groin was less than scour depth produced by straight groin.…”

Section: Figure 1 Groinmentioning

confidence: 99%

Turbulence Characteristic of Flow Near Laboratory Experiment Groin Fields

Wardhana

2019

MKTS

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Groin is hydraulic structure utilized to protect riverbank from erosion. Groin will shift away flow. Area just downstream of groin structure will be occupied by low velocity flow hence there will be sediment deposition. Turbulence mechanism between primary flow region and groin field having important role in sediment exchange needs to be investigated. Instantaneous flow measurement was conducted in order to investigate turbulence relation between series groin under various groin spacing. Laboratory experiment employed turbulence flow having Reynolds number range between 31,935-32,500 and Froude number range between 0.051-0.053. A MicroADV 16-MHz was used to measure 3D instantaneous velocity. The experiment findings expressed that Reynolds stress involving vertical velocity and did not show any specific distributions except at the lowest measurement elevation, while Reynolds stress showed specific distributions. Turbulence value difference between groin field and primary flow region at upstream of the groin field was significant. As the area was getting downstream, area containing high turbulence was wider. This work indicated that bed shear stress value tended to grow at downstream area of groin field. High difference bed shear stress value between primary flow region and groin field seized second groin field and third groin field.

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Section: Figure 1 Groinmentioning

confidence: 99%

Turbulence Characteristic of Flow Near Laboratory Experiment Groin Fields

Wardhana

2019

MKTS

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“…It would change with the river's dynamic discharge, making riverbank erosion a continuous process. The eroded bank/bed material is a source of sediment which deposits downstream where the flow turbulence/resuspension capacity is less (Dehghani, Azamathulla, Hashemi Najafi, & Ayyoubzadeh, 2013). It also leads to meandering formation, material movement, and lateral channel migration (Lawler, Thorne, & Hooke, 1997).…”

Section: Introductionmentioning

confidence: 99%

Turbulence structure and bank erosion process in a dredged channel

Arora

Patel

Lade

et al. 2023

River Research & Apps

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Riverbank erosion has significant geomorphological as well as anthropogenic consequences. The geomorphological impacts include form changes such as lateral channel migration, meanders, channel expansion, etc. The anthropogenic effects include the threat to floodplain human habitation, agricultural land, and stability of instream hydraulic structures and buried pipelines. Channel dredging for the extraction of sand and gravel has seen a multi‐fold rise in the last few decades. Therefore, riverbank erosion response to channel mining gains importance in river basin management. Sandpits dredged in the riverbeds can significantly impact the downstream riverbank stability. In order to assess these impacts, we conducted a series of experiments at a laboratory scale in a recirculating water flume. Three riverbank slopes, 25° (gentle), 31° (equal to the angle of repose of the bank sediments), and 40° (steeper than the angle of repose), were tested along with a sandpit. Remarkable changes in the turbulence structure of riverbank flow were found due to the channel pit. Pit excavation directly impacts the fluvial erosion characteristics of the riverbank. Pit action increases the Reynolds shear stress fields in the near‐bank flow, which causes progressive fluvial erosion of the berm at the bank toe. The erosivity of the main channel flow in the riverbank also leads to channel degradation, which increases the exposed height of the bank slope. Pit dredging leads to the generation of stronger ejection bursts which provide a mechanism for berm sediment mobility and erosion. The hydro morphological response of the riverbank due to sand mining was analysed, and process understandings are presented in the paper.

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“…Dehghani et al [8] study was to estimate the local scour depth and knowledge maximum scour depth by using two shapes (straight, L-head groynes in both direction). Their study was carried out by using two groups, the first group, comprised of two different shapes, the second group, comprised of upstream and downstream L-head groynes with various angles in both directions.…”

Section: Introductionmentioning

confidence: 99%

Countermeasure of Riverbanks Local Scour and Deposition Using Different Shapes of Multiple Groynes with Different Spacing

Majeed¹,

Abed²,

Ibrahim³

2022

MMEP

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In current study a computation fluid dynamic (CFD) technique was used to investigate the effect of groynes shape and spacing on the scour pattern and the maximum scour depth in open channel flow. CFD model have been validated throughout comparing the numerical results with three previous experimental studies for a single groyne located in open channel with three different shapes (L, quadrant, and parabola shapes). The comparison revealed very good agreement between numerical results of the maximum scour depth with the results of all experimental models. Moreover, investigations of the effect of multi-groynes (three groynes and four groynes) arranged in parallel with constant spacing and also with variable spacing have been done, the results showed that the best spacing between groynes equal to the length of the groyne itself, Finally, the CFD model have been used to investigate the best pattern for the groynes having different shapes arranged respectively, the results show that the pattern starting with parabola shape gives minimum scouring depth.

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Local scouring around L-head groynes

Cited by 34 publications

References 12 publications

Turbulence Characteristic of Flow Near Laboratory Experiment Groin Fields

Turbulence Characteristic of Flow Near Laboratory Experiment Groin Fields

Turbulence structure and bank erosion process in a dredged channel

Countermeasure of Riverbanks Local Scour and Deposition Using Different Shapes of Multiple Groynes with Different Spacing

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