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Scour is a natural process in rivers initiated by the erosive action of the activated water. Spur dikes are built across the flow to defend the stream erosion and facilitate the shifting of the river away from the bank. The spur dike weakens due to stream bed scouring and erosion, which is usually documented as the key reason of spur dike failure....
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... to the flow separation, a horseshoe vortex forms in the scour hole at the upstream side of the dike and a wake vortices system develops at the downstream side. A diagram with three-dimensional characteristics and different vortices is illustrated in Figure 2, ( Kwan 1984). Zhang and Nakagawa (2008) examined the flow behavior and concluded that the maximum influenced flow around spur dike depends on approach velocity and length of spur dike. ...
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Citations
... 23 A comprehensive summary of scour phenomena was provided related to spur dikes, encompassing various facets such as flow patterns, temporal and maximum scour depth, and factors influencing scour development. 24 The amount of sediment trapped by BLS was calculated and compared with impermeable groins. 25 It was found that the average sediment concentration collected at the downstream in case of BLS was 128 ppm and 133 ppm for impermeable groins. ...
River training is crucial for safeguarding river banks against erosion and preventing damage during floods. Various established methods like spurs, dykes, and revetments have been employed for many years. Researchers are currently investigating a novel river training approach known as bandal-like structures, aiming to demonstrate their cost-effectiveness as a potential alternative to existing structures. The bamboo bandalling technique effectively controls erosion and promotes sedimentation in rivers, reducing sediment loads. Biodegradable bamboo, readily available and cost-effective, ensures minimal harm to aquatic life. However, these structures require replacement after a single monsoon season, making them suitable for short-term river training in low-discharge, unsubmerged conditions. The current study analyzes scour around bandalling structures, emphasizing the need for further research to address discrepancies in velocity distribution and optimize scour control. Numerical simulation strengths and weaknesses highlight the suitability of Artificial Neural Networks, Genetic Algorithms, and Computational Fluid Dynamics for different aspects of the investigation.
... An accurate scour depth estimation is required for a safe design of spur dikes. Different empirical formulae are available in the literature to predict the scour depth near the spur dike (Pandey et al. 2018). Kothyari and Ranga Raju (2001) considered spur dikes as thin abutments and suggested using the developed abutments equations for spur dikes. ...
In this study, different geometrical configurations of T-head spur dikes, such as spur dike length(l=6, 9, and 12 cm), wing length (λ=0.5, 0.75l, and l), and wing orientation (θ=60°, 90°, and 120°) are used to investigate the local scour. The T-head spur dike with l=9 cm,λ=l, andθ=90° is found as the optimum configuration. The turbulent kinetic energy flux in the vertical direction is positive in the non-scour zone and negative in the scour zone with a higher magnitude, resulting in the transport of turbulent energy towards the bed that leads to scouring. The sweep events dominate against the ejection events in the scour zones, but in the non-scoured zone, it is the opposite. A regression equation was developed to estimate the scour depth around the spur dike, and satisfactory results were obtained.
... The scour occurring near or downstream hydraulic structures has garnered significant attention over recent decades (Rajaratnam 1981). Usually, soil erosion commences the scouring process in the vicinity of hydraulic structures like bridge piers, weirs, grade control structures, downstream dams, and trajectory bucket-type spillways (Hoffmans and Verheij 2021;Pandey et al. 2018). Scour caused by submerged jets is a prominent phenomenon resulting from the controlled release of fluid through nozzles or outlets (Gupta et al. 2022;Yeh et al. 2009). ...
This study utilized hybrid artificial intelligence (AI) models, created by integrating the extreme gradient boosting model with particle swarm optimization (XGBoost-PSO) and differential evolution (XGBoost-DE) algorithms. These models are applied to predict scour depths for two conditions, i.e., static (jet is turned off) and dynamic (jet is operational), that are formed due to submerged circular vertical jets. To assess the model’s effectiveness, a comparative analysis is conducted among individual AI models, including support vector regression, adaptive neuro-fuzzy inference system, and traditional regression methods, such as multiple linear regression and multiple nonlinear regression. The results from the cross-validation analysis reveal that the XGBoost-DE and XGBoost-PSO models showcase the highest performance metrics. In the testing dataset, both models achieve a high coefficient of determination (
) of 0.93 for static scour depth prediction. For dynamic scour depth, the XGBoost-DE model achieves an
value of 0.88, while the XGBoost-PSO model achieves an
value of 0.91, confirming their predictive capabilities. The XGBoost-DE model exhibited low values of root mean square error (RMSE) and mean absolute error (MAE) at 0.199 and 0.09, respectively, in static scour depth prediction. Similarly, the XGBoost-PSO model posted RMSE and MAE values of 0.227 and 0.159 for dynamic scour depths. In a nutshell, the significance of the study includes: (1) the utilization of first-hand hybridized AI models to predict the scour depths under submerged circular vertical jets and (2) the demonstrated superiority of these hybrid models over existing methods. These advancements provide valuable support to civil engineers in accurately estimating scour depths under submerged circular vertical jets.
... Previous researchers have opted to use structures like groins or spur dikes to function as restoration structures to minimize erosion around the outer bank, hence, developing the natural habitat for the aquatic life (Haider et al., 2022). The spur dike acts as a defense system against erosion and scouring in rivers and acts as a hindrance for the diversion of the river from its original course (Pandey et al., 2018). These groins or spur dikes can be made of various materials like rock, stones, soil, gravel, etc. ...
... There were four non-submerged and deflecting (installed at an angle of 90 with the channel) (Pandey et al., 2018) spur dikes with varying porosity (P) (ratio of the area of openings to the total area of spur dike). These were installed at all five positions one at a time, making an angle of 90 with the curved channel at each location (Kang et al., 2005). ...
A river's planform pattern changes due to erosion of banks and the bed near the outer bend. The primary cause of these planform changes is the formation of helical flow patterns in response to centrifugal forces. Uncontrolled bed scouring can have a negative impact on the river's geometry, aquatic habitat, and floodplains. To alleviate this scouring, various structures, such as spur dikes, can be placed at any accessible location along the bend. The current research was accomplished by installing two meandering models with different sinuosities of 1.3 and 1.5, in a flume. For both sinuosities, the maximum bed scour was observed at an approximate angle of 45 relative to the bend apex. Thus, the main objective was to control this maximum scour by installing spur dikes with varying porosities, ranging from 0% to 75%, at five locations along the outer bend. The spur dikes were found to divert the helical flow regime away from the outer bend and protect the riverbed from severe scouring. However, the results show that the effectiveness of spur dikes decreases as sinuosity increases. Furthermore, for both meandering models, a 50% permeable spur dike installed at the þ30 location yielded the best performance. Finally, a regression-based predictive equation is proposed to determine the proportion of scouring around a spur dike in a meandering channel.
... In general, scour may be classified into two types: general scour and local scour. Scour is not limited to a particular building; it can also occur across a larger area (Pandey et al. 2018). It involves sediment extraction from the bed or banks of a river or channel due to alterations made to the channel's form. ...
The scouring process near spur dikes poses a threat to riverbank stability, making it crucial for river engineering to accurately calculate the maximum scour depth. However, determining the maximum scour depth has been challenging due to the intricacy of scour phenomena surrounding these structures. This research introduces a reliable ensemble data-driven model by hybridizing random tree (RT) using additive regression (AR), bagging (B), and random subspace (RSS) for predicting scour depths around spur dikes. A database of 154 experimental observations was collected from Ezzeldin et al. (2007), Nasrollahi et al. (2008), Pandey et al. (2016), and Zaghloul (1983), with 103 and 51 observations used for training and testing subsets, respectively. A dimensionless analysis was performed on the collected dataset, selecting four variables as input variables (v/vs, y/l, l/d50, and Fd50) and ds/l as response variables. The performance comparison demonstrates that B_AR_RT has a better coefficient of determination (R2) of 0.9693, root mean square error (RMSE) of 0.1305, and Nash–Sutcliffe efficiency (NSE) of 0.9692. Finally, a comparison of the best hybrid model has been done with previous studies, and sensitivity analysis is performed to determine the most influential parameter for predicting the scour depth around spur dikes.
... This exchange induces ne sediment in suspension to inltrate into the pores of riverbed material, resulting in the deposition of ne particles inside the pores of the channel bed surface and its substrate (Einstein 1968;Diplas and Parker 1992;Gibson et al. 2007). Entrainment of the embedded ne particles occurs both during their deposition and consequent ow conditions (Cuthbertson and Ervine 2007;Pandey et al. 2018Pandey et al. , 2019. ...
The deposition of fine sediments within the surface layer of bed material has a significant impact on the aquatic life that exists in the bed substrate. The current study conducted laboratory experiments to measure the sediment deposition process using a tilting flume. For the experiments, three different uniformly sized gravels were used. The accumulation of fine sediment particles within the pores of the coarse sediment bed surface moving as bed load was investigated at various equilibrium quantities of suspended load in the flow. The present study utilizes a numerical model to quantify the loss in porosity of surface layer bed material induced by this process. The entrainment of deposited particles by clear water inflow to the channel is also investigated. The findings of this study will be useful in future research on the ecological and environmental consequences of riverine systems.
... The greater magnitude of scour depth with maximum IPD length (17.5 cm) makes sense because considering flows with relatively high Froude numbers have accelerated flow rates [51], that also intensifies the shear stress trying to act on the bed, leading to the formation of a deep scour hole. This observation is corroborated by recent studies [11,52,53]. dimensionless and ℎ to obtain good knowledge of the interaction between / ℎ and permeability and pile shapes, respectively. ...
... The greater magnitude of scour depth with maximum IPD length (17.5 cm) makes sense because considering flows with relatively high Froude numbers have accelerated flow rates [51], that also intensifies the shear stress trying to act on the bed, leading to the formation of a deep scour hole. This observation is corroborated by recent studies [11,52,53]. ...
A flood protection dike blends seamlessly with natural surroundings. These dikes stand as vital shields, mitigating the catastrophic effects of floods and preserving both communities and ecosystems. Their design not only aids in controlling water flow but also ensures minimal disruption to the local environment and its biodiversity. The present study used a uniform cohesionless sand with d50 = 0.9 mm to investigate the local scour process near a single combined dike (permeable and impermeable), replicating a flooding scenario. The experiments revealed that the maximum scour depth is likely to occur at the upstream edge of the dike, resembling a local scour observed around a scaled-down emerged dike in an open channel. The scour hole downstream of the dike gets shallower as it gets smaller, as do the horseshoe vortices that surround it. Additionally, by combining different pile shapes, the flow surrounding the dike was changed to reduce horseshoe vortices, resulting in scour length and depth reductions of 48% at the nose and 45% and 65% at the upstream and downstream dike–wall junction, respectively. Contrarily, the deposition height downstream of the dike had a reciprocal effect on permeability, which can severely harm the riverbank defense system. The combined dike demonstrates their ability to mitigate scour by reducing the flow swirls formed around the dike. The suggested solutions can slow down the rapid deterioration and shield the dike and other river training infrastructure from scour-caused failures.
... The cross-sectional geometry of the channel changes by installing a spur dike along the riverbanks, which is responsible for the change in flow properties around it. The upstream side of the spur dike divides the flow, which forms vortices, and local scour occurs at the downstream side [19,20] and it may lead to scour holes in the vicinity of the dikes. [4,21,22] The mechanism of scour around spur dike is similar to abutments, and it is explained by researchers. ...
... There are several experimental studies conducted on scour around the spur dikes and other hydraulic structures. [4,15,20,21,26] ...
Spur dikes are popular river training structures used for flow diversion, flood control, bank protection, and improving navigation. This paper aims to study the numerical modeling of scour depth in the vicinity of a rectangular spur dike using the renormalization group (RNG) turbulence model and sedimentary van Rijn model with nested mesh configuration using FLOW-3D. This study is also carried out to analyze the three turbulence models such as RNG, k−ε, and Large-Eddy simulation (LES), for estimating the scour depth and evaluating the temporal variation of maximum scour depth. It is observed that scour depth is overpredicted with the LES model configuration used in the present study, as compared to k−ε and RNG models. Furthermore, the scour depth increases by increasing the bed load coefficient near to the spur dike. Simulated results show a good agreement within a 5% error with experimental results regarding the net change of sediment elevation and scour depth.
... Its purpose is to redirect the water away from the riverbank in order to mitigate erosion by redirecting the water flow. Consequently, the repelling spur dike is anchored perpendicular to the flow's direction [2]. . Variations in the water bodies (i.e., river) beds and banks results due to different features such as shape of channel (width, depth), the material from which river bed is made-up, amount of sediment carried by water bodies. ...
The present study examines how adjusting vegetation patches in a rectangular open channel with two impermeable spur dikes alters the displacement of the recirculation region. The Reynolds stress turbulence model is implemented via the 3D numerical code FLUENT (ANSYS). Mean stream-wise velocity profiles were drawn at selected positions and at mid of flow depth i.e., 3.5 cm, a horizontal plane is cut through the open channel for analyzing velocity contours and streamline flow. The findings indicate that the stream-wise velocity profiles showed fluctuations in the presence of different shapes and arrangement of cylindrical patch discussed and the maximum velocity within the field of spur dike is of the order of 0.018 m/s due to the prism shape. By changing the position of the cylindrical patch, the location of the recirculation region displaces within the field of impermeable spur dike.
... Scour holes are often not only caused by turbulent flows induced by engineering works (Hoffmans and Verheij, 1997;Termini, 2014;Pandey et al., 2018;Liang et al., 2020) but also occur in natural settings such as river or tidal confluences (Kjerfve et al., 1979;Best, 1986;Best and Ashworth, 1997;Ginsberg and Perillo, 1999;Ferrarin et al., 2018;Smith et al., 2019). In many river deltas and estuaries, scour holes have been reported including the Mississippi (Nittrouer et al., 2011), Ganges-Brahmaputra (Best and Ashworth, 1997), Mahakam (Vermeulen et al., 2014), Mackenzie deltas (Beltaos et al., 2011), Tisza river (Cserkész-Nagy et al., 2010) and Venice lagoon (Ferrarin et al., 2018). ...
... Previous research on scour hole formation largely focused on hydrodynamic conditions causing their development or the morphological characteristics (e.g. Kjerfve et al., 1979;Best, 1986;Best and Ashworth, 1997;Ginsberg and Perillo, 1999;Pierini et al., 2005;Gharabaghi et al., 2007;Blanckaert, 2010;Ottevanger et al., 2012;Vermeulen et al., 2014;Ferrarin et al., 2018;Pandey et al., 2018;Liang et al., 2020). A large number of scour holes have also been identified in the heavily engineered river channels of the Rhine-Meuse delta. ...
Scour holes are common features in deltaic rivers which can destabilise embankments through oversteepening of the river bed. Their development has been studied extensively from the hydraulic perspective, but another important control is the erodibility of the river bed which varies considerably due to thickening of heterogeneous deltaic substrate towards the coast. Therefore, we assessed the influence of delta-scale geological heterogeneity and local subsurface architecture on scour hole formation in addition to the hydrodynamic controls. We (1) created an inventory of 165 scour hole locations in the Rhine–Meuse delta, (2) assessed the hydrodynamic conditions at the locations, (3) extracted geometric characteristics and (4) determined the subsurface architecture from geological data. Central and lower delta branches have 0.6–0.7 scours per km while upper delta branches have less than 0.2. Downstream, 58% of scour holes were related to architectural elements, notably sand bodies from former Holocene channel belts and Early Holocene cohesive beds. These scours have steeper slopes due to higher proportions of cohesive sediments near the river bed. Furthermore, scours related to channel belt sand bodies are limited in downstream length and depth, up to maximum of approximately two times the water depth. From our results, we provide a delta-scale explanatory framework that relates the position of present-day river channels with respect to Pleistocene river deposits and Holocene fluvio-deltaic deposits to scour hole formation. Upstream rivers are incised in Pleistocene deposits showing less local variation in erodibility. The majority of scour holes here relate to engineering works. In central and lower delta branches, geologically inherited heterogeneity of the Holocene substrate at critical depths near the channel bottom adds to anthropogenic induced scours and results in high abundances. This demonstrates that downstream variation in subsurface architecture should be considered as a key control on scour locations and characteristics for management purposes.
