Spur dikes are river training structures that developed from the natural river banks with proper length and angle from the flow dominant direction, cause to divert the flow attack at the riverside and the critical regions and directs the flow to the river central axis. There are several researchers focused on the effect of the spur dikes angles on the flow pattern however there is not any study on hockey spur dikes angle on scouring patterns. In present study, the effects of the hockey spur dikes angle on scouring and the bed topography was carried out experimentally while the results were compared to those provided for L-shape. The experiments were conducted on a series of hockey spur dikes also the L-shape in three various angles equal to ,  and  (towards the downstream channel lateral walls) inside a laboratory flume in 10.5m length, 0.5 width and 0.5m height under the clear water conditions. The results revealed the scour hole parameters including the length and thickness of the sediment hill are lower in hockey spur dikes than the L- shape by increasing the spur dikes angle. Furthermore, the maximum scour depth, mean area and volume of scouring are increased by 41.4, 41 and 75.5 percent in hockey and by 33.8, 39 and 73 percent in L-shape through increasing the angle from   to , respectively. Also, no scouring was taken place in the vicinity of the channel lateral walls downstream the hockey spur dikes, hence, those beter act against the destruction also in protection of river beaches against the erosion, with respect to the L-shape.

Spur dikes are structures that constructed for protection of the river walls against the erosion. Spur dikes are generally built perpendicular or at an angle to the river bank or revetment, protruding into the watercourse. The effect of the geometrical characteristics of the hockey spur dikes on formation developing of scour hole has been rarely studied. Spur dikes. The current study aims to evaluate the effect of the length of the hockey spur dike on the formation and development of scour hole and comparing with that effect in L-shaped spur dike. In this direction, all experiments were done in clear water conditions using the spur dikes in length of 8 cm and 12 cm and in a laboratory flume. The results asserted that the dimensions of the scour hole and the length and thickness of the sedimentary hill were increased by raising the length of the spur dike. However, this increment was lower in hockey spur dike than the L-shaped spur dike. The maximum depth, area and the volume of the scour hole were also increased by raising the length of the spur dikes. This increment in-average was equal to 57.5 and 67.7 per cent in L-shaped spur dikes and equal to 33.3 and 42 per cent in hockey spur dikes for two different lengths of spur dikes. Furthermore, no scouring was observed in downstream section of the hockey spur dikes near the wall. Therefore, the dimensions of the scour hole around the hockey spur dike was lower than those in the L-shaped spur dikes.

Improvement of the river route is one of the goals that considered in using a spur dike to control the flood, prevent bed erosion, stabilize and protect the walls, and set river width. Spur dikes are structures that with adjustment hydraulic conditions and make smooth flow cause to reduce flow erosion power and the ability to carry sediments. And also makes good situations for sedimentation and sides consolidation. Spur dikes are permeable and impermeable. Impermeable spur dikes have different shapes which according to erosion amount and condition can be used. Common spur dikes have simple, L and T-shaped geometric shapes. This research has been conducted to optimize the various combinations of spur dikes to reduce scouring. All of the scour and flow measurements were collected in a flume with 14 m long, 1. 5 m wide, and 0. 6 m deep located at the Soil Conservation and Watershed Management Research Institute. Impermeable spur dike with different geometric shapes were tested in a series with 3 spur dikes for different compositions in U/Ucr=0. 95 conditions. Due to threshold flow condition by using Shields parameters in all tests, the calculated discharge at the mentioned conditions is 30 Lit/s. For determine the equilibrium scour depth for each geometric, control test with 30 hours have been done. The first spur dike in all combinations was T-shaped. The results show that for first spur dike in combinations, in 10% of scouring equilibrium time, about 90% of scouring occurred. So with these results, 300 min (5 hours) test time was selected for do all main tests to achieve more than 85% of scouring. Also, in the results of different tests it was observed that maximum scour depth happens around first spur dike. So geometry of first spur dike is very important in reduce average scour depth in combinations. Mean scour depth in these combinations for first, second and third position respectively are about 2. 44y, 1. 21y and 0. 75y which in that for second and third positions with 50% and 69% have fewer scour depth in comparison with first position. Combination (T L T) is the best composition for the lowest average scour depth in all three positions, which 2 times the flow depth have erosion. The best performance in the whole range of spur dikes due to the amount of erosion volume is for the composition (T I I), that’, s about 70% of the massive erosion in other compositions. Mean scour depth in all positions for these 2 series are 1. 39y and 1. 63y. Average scour depth in (T T T) series is 1. 41y which more than (T L T) combination. The reason for this results can be effect of middle L-shaped spur dike on T-shaped spur dike scour depth in third position. This effect cause to reduce scouring in about 28%. (T I I), (T L T) and (T T T) series spur dikes are the best combinations which each one has special performance, therefore, for design, the best composition should be choice for target of exploitation and optimal economic conditions.

Spur dike is one of the river training structures used for deviating the river flow from critical and erodible areas towards the central axis. As a result of flow, a zone with high turbulence around the spur dike is developed. The hydraulic process results development of the scour hole around the spur dike and settlement of sediment in the downstream and sides of the river. Several plan view shapes, such as straight, T-shape, and L-shape of spur dike have been constructed worldwide in accordance with different river environments. While scouring in spur dike structures results a serious threat to the river so it is needed to be investigated in this field. This paper describes flow field and scouring around series of Triplex rippling spur dikes (directed to the upstream) with a distance of 3.5 times of the effective length of the spur dike in the outer bank of a sharp bend channel. The first spur dike is located at section 30 degree from the start of bend. The experimental channel is a 90 degree channel with rectangular section. The radius of curvature to the channel width is 2, which is classified as a sharp bend. The bed materials used are uniform sand with mean diameter of 1.28 mm, its standard deviation coefficient of 1.3 and the relative density of sediment 2.35. Constant discharge of 25 l/s was used in the experiments. The results of flow field on flat bed and a scouring experiment are presented. The scouring test was done in 24 hours and in the moving threshold (U/Uc = 0.98) under clear water condition. Flow field was recorded using the Vectrino II profiling velocimeter (NORTEK) as it can profile water in a 3 cm column. Dye injection technique is also used for flow observation. It was found that in the levels upstream of the first spur dike and adjacent to the bed, stream lines are deviated towards the inner bank. While in the middle levels, flow lines upstream of the spur dike is almost parallel to the channel walls and approached the spur dike, resulting deviation in the separation zone. In the scouring experiment it was obvious that at the beginning of the experiment, thus creating the down flow upstream of the spur dikes, scouring initiates near the wing of each spur dike and further develops by the horseshoe vortex. Then after scour hole upstream of the second and third spur dike starts. Details of sediment movements at the beginning of the experiment and after development of the scour hole are addressed. The circulation flows and secondary flows which formed in bend and the position of separation zone at different layers are also discussed. Scouring experiment illustrate that the amount of scour at the upstream of the second spur dike is about 33 % and at the upstream of the third spur dike is about 81 % of the maximum amount of scour that occurs upstream of the first spur dike. The mechanism of scour and flow field are also studied in this paper.

This paper addressed variations in scour and flow patterns around T-shaped spur dikes located at a 90 degree mild bend. Simulation of flow and scour patterns was conducted through 7 distinct modeling for a single and non-submerged spur dike and also with series spur dikes at distances of 2. 5, 3. 5, and 5 times the spur dike length from each other in non-submerged and submerged (25% submergence) modes using a numerical model. A comparison between the experimental and numerical results was carried out in nonsubmerged and single mode. Accommodation of experimental and numerical data was indicative of the efficiency of SSIIM numerical model in scour and flow pattern simulation in bend channels. The results of this study demonstrated that the dimensions and location of vortices, as well as the degree of scour, would change by varying the distance between the spur dikes, and spur dikes’ submergence ratio; hence, in a submerged mode, increasing the distance between the spur dikes would increase the degree of scour and the maximum sedimentation, while increasing spur submergence would decrease the maximum scour and sedimentation, and the maximum secondary flow strength occurring at the upstream end of the first spur dike would decrease by 34. 55%. In addition, a 25% submergence of spur dikes would lead the maximum scour to occur at the distance from the third spur dike to the bend exit.

Spur dikes are hydraulic structures that are used to protect river banks. In this paper, parameters influencing flow pattern around non-submerged attracting series of T- head spur dikes in straight channel are investigated. Evaluating of the flow pattern indicates that using spur dikes causes reversed flow and increasing the horizontal and vertical components of velocity at upstream of spur dikes. Longitudinal component of velocities at the front of the first spur dike wing is more than longitudinal velocities in the front of the second and third spur dike wing and in front of the second spur dike wing is more than third spur dike wing. The horizontal component of velocity are maximum the surface near to bed in reversed flow region and the negative transvers velocities of reversed flow are maximum near the free surface between spur dikes and in the front of the second and third spur dike wing. The deep positive velocities are seen in the edge of wing upstream of first spur dike and between spur dikes. Investigation of turbulence kinetic energy in flow pattern shows that it is maximum in the edge of wing upstream of first spur dike and has increased in wing of spur dikes' shear layer. Investigation of Reynolds stresses in flow pattern shows that component {formula} is maximum compared to two other components and the maximum value of that is occurred in the downstream and among of spur dikes. The maximum value of {formula} component is respectively about 5 and 6 times the values of {formula} and {formula} components. Component {formula} is at minimum compared to two other components and component {formula} at the edge of wing upstream of spur dikes and the minimum value of that occurs in the downstream and among of spur dikes. Investigation of bed shear stress shows that the maximum of bed shear has occurred at the edge of wing upstream of the first spur dike.

The spur dike has been known as one of the most common organizing constructs of the river to reduce the erosion of coasts and river banks. These structures are developed with the right lengths and angles towards the flow of the natural walls of the river that cause flow deviation from the sides and lead it toward the central river axis. In this experimental study, the flow pattern around the simple series spur dike in the meandering channel with a sloped erodible wall consisting of three consecutive arches with angles of 45, 90 and 45 degrees, has been studied for 40, 35 and 30 liter/sec rates. The results indicate that the collision position of the first line of flow in the near bed to the inner wall of bend no. 2 in discharge 40 liters per second earlier than discharge 35 liters per second and in discharge 35 liters per second earlier than the discharge 30 liter per second. So that the collision position of the first line of flow in the near bed to the inner wall of bend no. 2 in discharge, 40, 35 and 30 liters per second, respectively, in the -18, -15 and -10 degree sections compared to the central arc of the mentioned bend. In conditions of the presence of spur dikes, the vortex dimensions change with the depth of movement, so that moving towards the surface of the water in a fixed discharge, due to the tendency of flow to the outer wall, the slope of the bend wall and increasing the level of contact surface of the spur dike length, the vortex dimensions are increased.

Erosion is one of the most worrisome issues associated with the river and coastal sides. The use of spur dikes is one of the newest methods for controlling and reducing erosion. The spur dikes are in various forms, such as simple, l-shaped and t-shaped. In this experimental study, the effect of different geometry of upstream and downstream spur dikes on the scouring of middle t-shaped spur dike was study for a series of spur dike combinations. Experiments have been analyzed for movable bed in the threshold of motion condition. The results of this study showed that the average scour depth around the mid-t-shaped spur dike is about 0. 8 times the flow depth. The best performance of the t-shaped spur dike occurs when the upstream spur dike is l-shaped and downstream is t-shaped (L T T). In fact, the lowest volume and average scour depth due to the all situations is related to this combination. The erosion volume was calculated using the Surfer software. The average scouring volume of this combination is 0. 063 m3 and the average scour depth is about 1. 21 times the flow depth. At the site of the first spur dike, the entire amount of erosion on the side of spur dikes but by crossing the spur dikes, erosion is directed toward the opposite.

One of the most commonly method of river bank erosion is the use of the spur dikes. Spur dike creates rapid variations in flow, sediment transport, and hydraulic geometry of river. The mechanism of flow and sediment discharge in channel bend is very complicated, when a structure like bridge pier, spur dike, and abutment is constructed in a bend. Most of the previous investigations on the flow behavior and scour around spur dike were carried out in straight flume. In this paper results of experiments on scour around spur dikes under clear-water condition in a channel bend are presented. In order to estimate the influence of spac and locations of spur dikes on scour hole extensive experiments were conducted in a 90o channel bend. Sand with uniform grain size with a median size d50=1.28 mm was used as the bed materials. Spur dikes were made of Plexiglas with a thickness of 1cm and length of 9 cm fixed to the side of flume. Experiments were performed near threshold condition in straight channel i.e.0.9<U/Uc<1 (U is approach velocity and Uc is critical velocity for sediment movement). The flow visualization was carried out by injecting potassium permanganate and with a help of a thin ribbon, then photographing and videotaping its trace. Experiments were conducted by using two spur dikes with four different spaces (2.5, 5, 7.5 and 10 times of spur dike length) in three different situations in the bend for the first spur dike (30o, 45o and 60o). Results show that the space and situation of spur dikes have important role on shape and dimensions of scour hole. Results also show that by increasing the space between spur dikes and the angle of situation of two spur dikes, the depth of scour around second spur dike increases. The maximum relative depth of scour for second spur dike to first spur dike was correlated to the space and situation of spur dikes in the bend.

Spur dike is a structure that extends transversely from the river bank toward its thalweg and deflects the flows away from the bank toward the center. One common type of this structure is the T-shaped spur dike, and the wings present in this dike can have major effects on the proximate flow pattern. In this study, the turbulent flow around three attracting T-shaped spur dikes placed in series was simulated using the FLUENT, the finite volume method and the k-ε turbulence model. The results of numerical modeling show that increasing the dike length and the spacing between dikes both alter the flow pattern around the structure, but flow pattern is more affected by the increase in the dike length than by the increase in the dike spacing.