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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.

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 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 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.