EFFECT OF SEDIMENT SIZE ON SCOUR

Abstract

This report presents the results of the studies. carried out on the effect of sediment characteristics on scour at and around spur-dikes in a movable bed. The study is in general a continuation of the work on local scour, being carried out at this University since 1959 by GARDE(7.9)* GARDE and SUBRAMANYA (8), NAMBUDR.IPAD (27) and SASTRY (28). A logical approach to the problem by the dimensional analysis Yielded a functional relationship for the maximum depth of scour. This was verified in rectangular$ recirculating flumes with beds comprising different sediment size. The results indicated the dependence of scour on the sediment and fluid charaoteristios,as defined by the fall-velocity Reynolds Number of the bed material. Froude Number of flow was found to be a suitable parameter to represent the effect of flow characteristics as compared to the discharge intensity at the contracted section or the velocity of flow. The effect of Froude Number and Sediment size on other aspects of scour was also investigated.