Experimental studies of scour around multiple spur dikes in channels

Spur dike is hydraulic structure extending into river at different angles provided to protect banks from excessive scour. Furthermore, scour may develop around the spur dikes itself which further threatens the stability of hydraulic structures. Therefore, in addition to its hydraulic significance, safety of the hydraulic structures is also of prime concern. This paper endeavors to investigate the scouring around the series of spur dikes (3 no.) by changing permeability and angle of spur dikes (60o, 90oand 120o) with respect to the bank of the channel. Two types of spur dikes i.e. impermeable (0%) and permeable (20% and 40%) were used to conduct the experiments. It was noted that magnitude of scour around spur dikes increases as percentage of permeability increases irrespective of the orientation angle. However, it was also observed that the minimum scour occurred at spur dyke when placed at 90o angle and maximum when placed at 60o angle irrespective of % age of permeability.