Experimental investigation on scour depth around t-shaped spur dike influenced by upstream and downstream spur dikes

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.