An experimental investigation of the equilibrium depth of local scour around side-weirs located on an alluvial river is presented in this paper. A sand bar in the middle of the channel and a scour hole close to the weir side is formed because of changes in shear stress field and velocity at the downstream end of the side weir. The depth of clear-water scour increases by time and approaches the equilibrium state asymptotically depending on approach flow velocity. The equilibrium depth of scour increases by the increase of the dimensionless parameters of approach flow velocity, water head ratio, side-weir length and sediment size. Although there is no scour for the dimensionless approach flow velocity less than 0.45, it increases almost linearly with the dimensionless approach flow velocity and the maximum value of scour depth occurs when it is equal to 1.0.

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