Bed morphodynamics at the intake of a side channel controlled by sill geometry

Ruijsscher, T.V. de; Hoitink, A.J.F.; Naqshband, Suleyman; Paarlberg, Andries

doi:10.1016/j.advwatres.2019.103452

Cited by 14 publications

(15 citation statements)

References 26 publications

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“…Moreover, the flow in the lower part of the water column is more geometrically steered (in this case aligned with the sill), causing a veering effect (I in Figure 15), whereas backing was observed in the free flow experiments of Hager (1987). This veering is in accordance with the observations of de Ruijsscher et al (2019) using a scale model based on the present geometry.…”

Section: Discussionsupporting

confidence: 94%

“…This is also analytically obtained from the potential flow model in equation () and Figure 7b, where ϕ rapidly increases close to the LTD head. The recirculation cell was also observed in experiments with a 1:60 physical scale model of the present field site by de Ruijsscher et al (2019), revealing a persistent flow separation phenomenon.…”

Section: Discussionsupporting

confidence: 78%

“…This finding is most probably caused by the presence of the sill, which limits the flow cross‐sectional area toward the side channel. This feature is known to linearly decrease the side channel discharge (de Ruijsscher et al, 2019).…”

Section: Resultsmentioning

confidence: 99%

“…We do hypothesize, however, that the flow pattern for the low‐angle bifurcation with a dike‐shaped, broad‐crested side weir as present at LTDs qualitatively resembles the free flow over a sharp‐crested side weir (Figure 2) even without applying a submergence correction factor. This presumption is strengthened by the observation of a flow separation cell downstream of the side weir by both de Ruijsscher et al (2019) (submerged side weir) and Hager (1987) (free‐flow side weir). Even less is known about suspended and bed load sediment transport associated with the flow over submerged side weirs, although it is of crucial importance for side channel stability.…”

Section: Introductionmentioning

confidence: 92%

“…Water and sediment division over the two channels can be steered by adapting the geometry of the sill at the bifurcation (de Ruijsscher et al, 2019); however, little is known about the spatial flow pattern at very low-angle bifurcations with a sill at the side channel entrance. We do hypothesize, however, that the flow pattern for the low-angle bifurcation with a dike-shaped, broad-crested side weir as present at LTDs qualitatively resembles the free flow over a sharp-crested side weir ( Figure 2) even without applying a submergence correction factor.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Diversion of Flow and Sediment Toward a Side Channel Separated From a River by a Longitudinal Training Dam

Ruijsscher

Vermeulen

Hoitink

2020

Water Resources Research

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A human-made entrance to a side channel separated from the river by a longitudinal training dam can be considered a new, emergent type of river bifurcation. To understand the processes controlling the diversion of flow and sediment toward the side channel at such bifurcations, a comprehensive field monitoring program was performed in the Waal River, which is the main branch of the Rhine River in the Netherlands. Local processes govern the flow field in the bifurcation region. The angle between the main river flow and the flow into the side channel increases with decreasing lateral and longitudinal distance to the bifurcation point, which corresponds to the head of the training dam. The general flow pattern can be well reproduced with a uniform depth, potential flow model consisting of a superposition of main channel flow and lateral outflow. For submerged flow conditions over the sill, the side channel hydraulic conditions influence the exchange processes, yet free flow side weir theory describes the flow field at this bifurcation type qualitatively well. The vertical flow structure in the side channel, which governs the sediment exchange between the main channel and the side channel, is steered by the geometrical details of the sill. The presence of the sill structure is key to controlling the morphological stability of this type of bifurcation given its primary influence on bed load sediment import and exerts an indirect impact on suspended sediment exchange.

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Section: Discussionsupporting

confidence: 94%

Section: Discussionsupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Diversion of Flow and Sediment Toward a Side Channel Separated From a River by a Longitudinal Training Dam

Ruijsscher

Vermeulen

Hoitink

2020

Water Resources Research

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Geomorphological development of aquatic mesohabitats in shore channels along longitudinal training dams

Flores

Collas

Leuven

2022

Remote Sens Ecol Conserv

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Longitudinal training dams (LTDs) are novel hydraulic engineering structures in the river Waal intended to facilitate intensive navigation and safe discharges in the main channel while providing sheltered habitats for aquatic biota in shore channels. Monitoring data collected using light detection and ranging, multibeam echosounder and aerial photography for the years during and after the construction of the LTDs were analysed in order to determine patterns of erosion and deposition, the retreat rate of steep eroding banks and shoreline length change through time. The LTD shore channels and two traditional groyne fields (references) were divided into nine mesohabitats based on physical attributes. Net erosion was estimated for eight out of the nine mesohabitats for the 2015-2020 period. Generally, there was a pattern of riverbed aggradation towards the LTDs and degradation or bank erosion towards the littoral zones of the LTD shore channels. This kind of continuous behaviour could be indicative of current or eminent channel and thus habitat stability. The bankline erosion in shore channels had mean retreat rates of 1.4-1.6 m/year. The shorelines were longer in sand-dominated mesohabitats, which could be key for habitat heterogeneity. The LTD shore channels offered more complex relatively natural continuous littoral zones than the traditional groyne fields while maintaining the multifunctionality of the river. Thus, the development of sandy shorelines in the LTD shore channels should be encouraged through management in order to enhance biodiversity. Geomorphological monitoring of the shore channels should continue in the future in order to detect any long-term changes in the sedimentary processes and ecological functions.

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Effects of Diversion Wall on the Hydrodynamics and Withdrawal Sediment of A Lateral Intake

Zhao

Zhang

et al. 2022

Water Resour Manage

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Bed morphodynamics at the intake of a side channel controlled by sill geometry

Cited by 14 publications

References 26 publications

Diversion of Flow and Sediment Toward a Side Channel Separated From a River by a Longitudinal Training Dam

Diversion of Flow and Sediment Toward a Side Channel Separated From a River by a Longitudinal Training Dam

Geomorphological development of aquatic mesohabitats in shore channels along longitudinal training dams

Effects of Diversion Wall on the Hydrodynamics and Withdrawal Sediment of A Lateral Intake

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