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One common method for Blank River protection and restoration is use of Spur dikes. Spur dikes either in the forms of group or single, depending on their permeability is classified an permeable and impermeable. Spur dikes restore flow pattern and prevent erosion of river banks. This leads to stability and immovability of river. However, they have some disadvantages; on installation they require drying river and erosion around their structure causes destruction (Anonymous, 2002, 2003) and (Anonymous, 2010). Due to the mentioned disadvantages use of spur dikes will be halted and use of vane, which has a higher environmental compatibility, is suggested. This study aims to introduce “composite structure”; a new structure with a combination of a Spur dike with different permeability and a single vane. The main aim of this study is to increase the amount of sediment transported behind the structure by water flow produced by the vane in the combination structure.

In order to protect the bank and prevent their erosion spur dike is used. Importance of these structures in the bend is more, because of secondary flows and consequently bank erosion. In this paper the flow pattern around series of vertical spure dikes in the 90° bend is investigated by a 3D RANS solver. In order to simulate the complex behavior of free surface and turbulent flow the volume of fluid method and realizable k-ɛ closure have been used, respectively. Two lengths spure dike (equal to 15 and 25 percent of width), two spacing (3 and 5 three times the length) and two depths (3 and 5cm) in constant discharge 25 lit/s in the mild bend flume with width 0.7m and depth 0.12 m has been examined. Comparison among the results with experimental data shows good agreement among them. Also, the results illustrate spure dike deviations maximum velocity to the inner bank in entrance of bend and then deviations to the middle flume. Increasing the length of the spure dikes increases the velocity but it has no effect on the location of the maximum velocity as in all arrangement occurrence in 71 to 81 degree of bend. In the case of shear stress, the maximum value is in the range of 71 to 81˚.

In this study, the performance of slot in the spur dike was evaluated as a way to reduce the scouring around the installed flat spur dike in a 180 degree bend and the development of scouring in the slotted spur dike was compared with that of the spur dike with no slot. To evaluate the effect of the slot on the development of scouring around it, a flat spur dike made of Plax Glass was installed in a position of 70 degrees from a bend (180 degrees) in the flume bed. After determining the maximum of scouring depth at the tip, to reduce the scouring around the spur dike, two slots with the determined height were placed in 4 different positions in the spur dike. Experiments with 4 different discharges and constant flow depth in clear water conditions were conducted. The results of the experiments showed that the created the slot reduced the scouring depth toward the spur dike. In both slots, the minimum of scouring depth was seen in a model with the closest position of the slot toward tip, and its maximum was seen in a model with the farthest position from the slot.

Sediment control at lateral intakes is known as a complicated issue for river engineers. In this study, numerical simulation of the impact of submerged vanes and spur dike on sediment control at lateral intake has been performed. For guiding flow into the diversion channel and increasing the vane performance, a single spur dike in opposite side of the intake has been utilized and the effects of spur dike length, the location of intake, and the angle of attack on reducing the movement of bed-load sediment into the diversion channel have been investigated. Obtained numerical results consisting with the experimental data confirmed this face that the effective performance of the vanes can increase using a proper spur result in eliminating the bed-load sediment ingestion rate into diversion channel. Then, numerical results were compared with experimental results and there was good agreement between them.

Examining the properties and behavior of the flow in the rivers and its associated structures is one of complex phenomena that make the use of software inevitable. First, the results of laboratory test carried out by Duan et al. (2009) in Minnesota university, are used verification and comparison of numerical simulations of FLOW-3D(version 9.3). The vertical spur dike was first simulated to verify the model results and the inclined spur dike with 60° and 30° to the flow direction was then considered. The simulation performed with FLOW-3D, for 650 seconds using turbulence models (k-ɛ, RNG, LES). By comparing different turbulence models with experimental results, the maximum scour depth at the tip of the spur dike was 8.82 cm. Then the maximum scour depth calculated by FLOW-3D in the turbulence models of (k-ɛ, RNG, LES) was 9.1, 8.9, 9.1 cm. So the error in RNG turbulence model is about 9 %, compare to the turbulence model k-ɛ, and of LES shows more agreement. In the simulation, the maximum scour depth at the tip of the spur dike 60° and 30° was 8.75 and 6.5 cm respectively.

Spur dikes and triangular-shaped vanes are structures that control the erosion of a river’s outer bend by the diversion of flow from there to its center. In this study, the erosion and sedimentation patterns around a spur dike and a triangular-shaped vane was investigated using an experimental model with a 90-degree mild bend. The triangular-shaped vane and spur dike with an effective length of one-fifth of the width of the canal (14 cm) and under different hydraulic conditions (Froude numbers 0.194, 0.214, 0.233 and 0.253) were tested. In all tests, a single triangular-shaped vane with an angle of 30 degree to the upstream direction, and a spur dike with an angle of 90 degree were installed in the outer bank of a flume in a 72° position, where the maximum scour depth usually occurs. For all tests, flow depth was kept constant equal to 13 cm. Bed topography was measured at the end of each experiment and the geometry of scour hole and point bar were determined. The results show that the maximum scour depth of the spur dike structure was more than that of the triangular-shaped vane. The average of maximum scour depth of the triangular-shaped vane and spur dike were 0.55 and 1.0 times that of the structure effective length, respectively. In addition, the maximum scour depth distance from the outer bank with a triangular-shaped vane was more than of the spur dike. The average distance of the maximum scour depth of spur dike and triangular-shaped vane structures from the outer bank were1.0 and 1.4 times the effective length of the structure, respectively. The point bar distance from the outer bank the spur dike structure was more for the triangular-shaped vane. The average point bar distance from the outer bank for spur dike and triangular-shaped vane were 0.34 and 0.1 times of effective length of the structure, respectively.

Spur dike is a hydraulic structure which has an essential role in reducing the shear force on river banks. The interaction between the structure and flow makes vertical and horizontal vortices, which are the main reason for producing a local scour hole around spur dike and finally damaging it. The behavior of the flow around a spur dike and the intensity of degradation and aggradation depend on different factors such as the type of the spur dike, its position, its angle with the bank, and some other parameters. One of the most important factors is the permeability of the spur dike. This experimental study focuses on the effect of spur dike’s angle and its permeability on scour hole dimensions in non-submerged conditions. According to the results, when permeability increased up to 50%, scouring decreased significantly. For Fr=0.24, and in the vertical position of spur dike (90 degrees) with 50% permeability, relative depth, length, and width of the scour hole decreased 67%, 75.3% and 45.5%, respectively in comparison with impermeable spur dike. Also for the angle of 120 degrees, relative depth, length and width of the scour hole declined 64.1%, 72.1% and 35.4%, respectively. Similar results were obtained for the angle of 60 degrees with the reduction of relative depth, length and width of the scour hole being measured 60.2%, 68.7% and 38.8%, respectively. In addition, for 50% permeability, the highest level of scouring was for the angle of 60 degrees, whose average relative depth, length, and width were 0.19, 0.7 and 1.2, respectively.

In this study, the performance of slot in the spur dike was evaluated as a way to reduce the scouring around the installed flat spur dike in a 180 degree bend and the development of scouring in the slotted spur dike was compared with that of the spur dike with no slot. To evaluate the effect of the slot on the development of scouring around it, a flat spur dike made of Plax Glass was installed in a position of 70 degrees from a bend (180 degrees) in the flume bed. After determining the maximum of scouring depth at the tip, to reduce the scouring around the spur dike, two slots with the determined height were placed in 4 different positions in the spur dike. Experiments with 4 different discharges and constant flow depth in clear water conditions were conducted. The results of the experiments showed that the created the slot reduced the scouring depth toward the spur dike. In both slots, the minimum of scouring depth was seen in a model with the closest position of the slot toward tip, and its maximum was seen in a model with the farthest position from the slot. [ABSTRACT FROM AUTHOR]

In recent decades spur dike has been one of the methods for bank protection and sediment deposition in rivers. In fact the spur dikes decrease the erosion and sediment potential rate of flow between them by improving the flow hydraulic conditions and controlling the shear velocities. Spur dike construction creates new conditions in river, which causes scour around the spur dike. Having knowledge about the amount of scour and sedimentation patterns around the spurs, helps for better and improved design of dikes. Therefore in this study the scour and sedimentation patterns around a Series of permeable and impermeable spur dikes is investigated. The experiments were carried out under the conditions of clear water and the percent of permeability of 0%(closed)to 50% in a flume with 0.56m-wide,7.3m- long and 0.6m-depth. The results show that the maximum depth of scour around the series of spur dikes and the amount of deposition between spurs reduced with increasing the spur permeability.