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Lateral intakes are very important for diverting a portion of the river flow and providing the proper flow depth. In cases where small dams are used to operate and control the river's water level for the intake and to meet downstream water needs, the opening and closing of the dam gates before the construction of the intake and during its operation are important. In the current study, the problem of reducing the water head in the intake basin of the Hemmat dam pumping station, especially in the seasons of low water and the accumulation of sediment in the intake inlet of the Hemmat dam located in the Khuzestan province of Iran, has been investigated. Focusing on different arrangements of opening and closing gates, using a spur dike and flow rates of 143, 100, 62, 32, and 12 m3/s to investigate velocity changes and the depth of flow at the water inlet, computational fluid dynamics (CFD) simulations were done. With the spur dike, the water intake efficiency is increased by 384% compared to the project's current state (operation without any flow control structure), and the hydraulic conditions resulting in sedimentation are eliminated. The flow depth of the water intake channel, with the spur dike, increases by 10% compared to the condition without it. It is worth mentioning that gate management also affects water supply efficiency. The results of the current study are a good example of the successful application of computer simulations for sustainable systems engineering. [ABSTRACT FROM AUTHOR]

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 +30° 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. [ABSTRACT FROM AUTHOR]

In this research, the flow features around a spur dike located in a 90˚ sharp channel bend have been studied experimentally in detail. Results showed that the effects of the spur dike on upstream sections increased by increasing α (spur dike location from the beginning of the bend). In addition, by increasing α , the horseshoe vortex (C3) and secondary flow in the channel bend (C1) strengthened. The energy and the Reynolds shear stress in the C3 region decreased by increasing α. It is recommended to use a Barycenteric Map (BM) instead of the normal Reynolds stresses to find the anisotropy nature accurately. A strong anisotropic condition was detected at the border of the recirculation flow region and the main flow. However, in the C3 and the interaction regions, the isotropy condition improved. In the main flow region, by increasing α, the isotropy degree improved. However, by increasing α, an increase in the development of the region with a high anisotropy degree towards the recirculation region was observed. The anisotropy degree in the near-bed layer region and the shear layer region is comparable. However, the anisotropy nature is different. The maximum error of the numerical simulation based on isotropic turbulence occurred at the shear layer region where the severe cigar-shaped turbulence occurred. [ABSTRACT FROM AUTHOR]

As a common structure for waterway regulation, the spur dike plays the role of both promoting nearshore sediment deposition and protecting riverbanks, so research on scouring and the corresponding structure is particularly important. In this study, the research results on the scouring of spur dikes and the placement of spur dikes in a river are summarized, including topics such as mechanism research, prototype observations, physical models, and numerical simulations. The current research trends and shortcomings of the scouring of spur dikes are summarized, and suggestions for optimization are proposed. [ABSTRACT FROM AUTHOR]

The position and depth of a scour hole around a bridge abutment are the important design parameters. The existing models have been mostly developed for steady flows, whereas real-life abutments often fail due to intrinsically unsteady flood streams. This study used nine hydrographs with different durations and skewness values and evaluated the ultimate scour depth and temporal scour depth variations for a rectangular abutment using the precise underwater image recording devices and then image processing method. Moreover, an eco-friendly permeable spur dike was employed to protect the abutment for the first time, and the testes were re-performed in the presence of the permeable spur dike. Although the hydrograph skewness had no significant effect on the ultimate scour depth, scour variations are dependent on the skewness of the hydrograph. The scour depth increased by up to 17% after the time of the peak flood, and then its variations became highly smaller, with the rising limb having a larger effect than the falling limb on the scour depth. Finally, equations were developed to calculate the scour depth during hydrographs. These equations enable bridge designers to have deeper insights into scouring around abutments during a flood and provide more reliable and economical estimates in the design of the abutment foundation size and depth. [ABSTRACT FROM AUTHOR]

This study concerns a method to install spur dikes in the Yodo River, for the purpose of bed deformation control and diversification of physical conditions around the spur dikes. The effects on the physical conditions around the installed spur dikes are evaluated, based on numerical analysis and field survey. The numerical analysis results show that, by installing spur dikes with a focus on hydraulic conditions of not forming sand bars, sediment deposition is suppressed in the main channel. The field survey results demonstrate that sediment deposition in the channel is also suppressed. By installing the spur dikes, some physical conditions around the installed spur dikes can be diversified. By installing spur dikes using large movable sandbags and changing their height after several years, it is possible to maintain the effect of the spur dike installation and diverse bed material conditions for a long period as adaptive management. (For example, by changing the height of the spur dikes 0.3 m lower, bed degradation is produced up to 0.5 m downstream of the spur dikes.) As a result, spur dike in case 8 (shape(c), height 0.7 m from average water level) is better for the present. After several years, changing the height of the spur dikes would be better. [ABSTRACT FROM AUTHOR]

Spur dikes are river training structures that have been extensively used worldwide for towards enhancing flood control and the stability of embankments and riverbanks. However, scour around spur dikes can be a major problem affecting their stability and hydraulic performance. The precise computation of temporal scour depth at spur dikes is very important for the design of economical and safe spur dikes. This study focuses on experimentally assessing the temporal variation of scour depth around a vertical wall spur dike and identifying the parameters, which mostly influence spur dike performance for a channel bed surface comprised of sand-gravel mixtures. In the current study, the authors did physical experiments in a flume based study to obtain new data, aimed at deriving a new predictive model for spur dike scour and comparing its performance to others found in the literature. It was found that the dimensionless temporal scour depth variation increases with an increase in (i) the threshold velocity ratio, (ii) the densimetric Froude number of the bed surface sediment mixture, (iii) the flow shallowness (defined as the ratio of the approach flow depth, y , to the spur dike's transverse length, l), and (iv) the flow depth-particle size ratio. It is also concluded that the temporal scour depth variation in the sediment mixture is influenced by the non-uniformity of sediment and decreases with an increase in the non-uniformity of the sediment mixture. A new mathematical model is derived for the estimation of temporal scour depths in sand-gravel sediment mixtures. The proposed equation has been calibrated and validated with the experimental data, demonstrating a good predictive capacity for the estimation of temporal scour depth evolution. [ABSTRACT FROM AUTHOR]

Scour around spur dikesin curved paths is one of the main reasons fortheir destruction. In this study, we conducted some experiments in a laboratory Plexiglas flume of rectangular section with an 180° bend to evaluate the effect of relative distance between twospur dikes in the bend on the occurred scour. For this purpose, two spur dikes were installed at relative distances of 2,3,4, and 5 times the length of the spur dikes and in four different relative lengths in the first half of an180° bend. Uniform sand with a uniformity coefficient of 1.3 was used inthe floor of the flume. All experiments were performed in four different discharges and a constant flow depth in clear water. The results show that with increasing the relative distance of spur dikes, the relative maximum scour depth increase at the opening of the spur dikes. [ABSTRACT FROM AUTHOR]

The spur dike is an important building in river guiding and bank protection. In the present paper, the turbulence intensity distribution around spur dikes with different structures under the same flow condition is studied through model experiment and it gives the turbulence contours. Combining with theoretical analysis, it can be calculated that the turbulence intensity in the arc-like spur dike and fan-like are relatively weaker than that of the hook-like spur dike, and the strongest turbulence intensity occurs around the trapezoidal spur dike. The conclusion will provide a scientific basis for a reasonable choice of the structure of a spur dike, which provides the references for a better structure of a spur dike. [ABSTRACT FROM AUTHOR]

Based on the HEC-RAS and River 2D modes, and taking 5% change rate of weighted usable area (WUA) as the threshold to define the spur dike-affected area of target fish species Acrossocheilus paradoxus in Fazi River in Taiwan, this paper studied the affected area of the fish habitat by spur dike, and, in combining with the references about the installations of spur dikes in Taiwan in recent 10 years, analyzed the relative importance of related affecting factors such as dike height, dike length (water block rate), average slope gradient of river way, single or double spur dike, and flow discharge. In spite of the length of the dike, the affected area in downstream was farther, and was about 2-6 times as large as that in upstream. The ratio of the affected area in downstream / upstream decreased with increasing slope gradient, but increased with increasing dike length and flow discharge. When the discharge was approximate to 10 years return periods, the ratio of the affected area would be close to a constant of 2. Building double spur dike would produce a better WUA than building single spur dike. [ABSTRACT FROM AUTHOR]

Abstract: Three-dimensional turbulent flow field was measured around an experimental spur dike by using a micro-acoustic Doppler velocimeter. Time fractions of turbulent burst events including outward interaction, ejection, inward interaction, and sweep were analyzed in each quadrant at the neighbor of the dike before and after the formation of scour hole. Over 80% of burst events near the bed have lower-order of magnitudes for both flat and scoured bed surfaces. Ejections and sweeps are prevalent before the local scour was initiated, and then outward interactions are dominant after the scour hole was formed. Conditional Reynolds stresses and high-order moments of turbulent velocities were analyzed along the thalweg. The magnitudes of u′–w′ pair were much larger than those of v′–w′ pair in the scour zone. Among four burst events, ejections and sweeps are the higher order events contributing to the Reynolds stresses. Since sediment entrainment and transport are closely associated with turbulent bursts near bed, the development of scour hole greatly depends on the higher order event near the bed. [Copyright &y& Elsevier]

Abstract: In this paper results of experimental study on scour and flow field around a T-shape spur dike in a 90 degree channel bend are presented. Experiments were conducted in a laboratory channel to measure the variations of bed topography under a clear water condition. The three dimensional flow field was measured by an Acoustic Doppler Velocimeter in a scour hole due to a T-shape spur dike. It was found that by increasing the Froude number and length of spur dike the amount of scour increases. Increasing the wing length of spur dike decreases the scour. The amount of scour at the upstream of spur dike is much more as compare to that at the downstream of spur dike. By increasing the wing length of spur dike the zone of flow separation expands. As a result the sizes of vortex increase. Details of flow field are also addressed in the paper. [Copyright &y& Elsevier]

Abstract: Spur dike is an important element in river training that creates rapid variations in flow field, sediment transport and bed topography. The mechanism of flow and sediment transport in a channel bend is very complex, especially when a spur dike is constructed in a bend. Most of previous investigations on flow behavior and scour around spur dike were carried out in straight channels. In this paper results of experiments on flow field and scour around a spur dike in a 90 degree channel bend are presented. Sand with uniform grain size was used as the bed material. Experiments were conducted for different locations and different lengths of spur dikes at the bend with different values of discharge. The three dimensional flow fields around a spur dike were investigated. The maximum depth of scour was correlated to the Froude numbers, lengths and the locations of spur dike in the bend. [Copyright &y& Elsevier]

For a physical model of the approach navigation channel of Three Gorges Project(TGP), flow patterns around a non-submerged spur dike placed as a mountain in a long rectangular glass flume were experimentally investigated with and without “sucking-spouting” water respectively. Based on rigid lid assumption and Dynamic Smagorinsky Model, all these vortex flows around the spur dike were numerically simulated and analyzed, which probably affect the whole flow field and then probably lead to sedimentations for silt-laden two-phase flows. Meanwhile, silt-laden flows were also investigated experimentally. Both the secondary flow region and the silt sedimentations downstream of the spur dike decrease greatly with “sucking-spouting” water compared to those ones without “sucking-spouting” water. The Finite Volume Method (FVM) was used to discretize the governing equations together with a staggered grid system, where the second order difference is employed for the diffusion terms and the source terms while the upwind difference QUICK is used for the convection terms. The computational results are all in fairly good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

ABSTRACT: Treatments of irregular boundary, bed deformation and free surface are main problems in 3-D flow and sediment model. Based on control equations of turbulent flow considering irregular boundary from liquid-solid two phase flow theory, the k-ɛ model and the Wall Function are adopted to develop a new model. In the model, apart from k-ɛ model and the Wall Function, the VOF method and the porosity concept are adopted to simulate water surface, irregular boundary and bed deformation. Using the new model, flow field, changing of water level, turbulent kinetic energy and its dissipation rate, and local scour-deposition around spur dike are simulated. Computed result is compared with experimental data. The model developed can successfully simulate the separating structure of flow and circumfluence around the spur dike, secondary flow in the circumfluence area, scour hole profile and bed contours and agree well with the experimental data. [Copyright &y& Elsevier]

Treatments of irregular boundary, bed deformation and free surface are main problems in 3-D flow and sediment model. Based on control equations of turbulent flow considering irregular boundary from liquid-solid two phase flow theory, the k - ε model and the Wall Function are adopted to develop a new model. In the model, apart from k - ε model and the Wall Function, the VOF method and the porosity concept are adopted to simulate water surface, irregular boundary and bed deformation. Using the new model, flow field, changing of water level, turbulent kinetic energy and its dissipation rate, and local scour-deposition around spur dike are simulated. Computed result is compared with experimental data. The model developed can successfully simulate the separating structure of flow and circumfluence around the spur dike, secondary flow in the circumfluence area, scour hole profile and bed contours and agree well with the experimental data. [ABSTRACT FROM AUTHOR]