study on influence increase effective length on the hydraulic characteristic and discharge coefficient in side weirs

one of the most important discharge control ways in hydraulic structures is side weir which is used in irrigation, water distribution, waste-water engineering, drainage, flood control and other water related projects.in order to increases cm value and control on water surface when there is restriction in the weir length(l), side weir with different geometry is used. in present research seventhly experimental tests were conducted on the semi-circular side weir with different lengths and heights(w).studied the influence of hydraulic and geometry variableson the cm valueand a new equation was developed to calculate discharge coefficient of the semi-circular side weir. the results indicated cm in the semi-circular side weir is 1.5 to 2 times morethan rectangular side weir.