In this paper the hydraulic characteristics of V-notch broad crested side weir have been experimentally studied. Sixteen V-notch broad crest weirs were constructed with six apex angles (θ=30º, 45º, 60º, 90º, 120º,and 150º)and the apex height change three times (p=5,10,15cm) for the first forth angles and change two times for the last two angles (p=10,15cm), each model can be tested by changing flow in the main channel several times and from the analysis of experimental results it was found that the coefficient of discharge(Cd) for the V-notch broad crested weir is depend on the hydraulic and geometric characteristics of channel and weir, and from the hydraulic characteristics of the main channel it was found that the coefficient of discharge (Cd) directly proportional to the main channel Froude number before side channel , and a maximum value of (Cd) can be reached for a larger acute V-notch angle , but a maximum value of (Cd) can be reached for the smaller obtuse V-notch angle. Also from the hydraulic and geometric effect for both channel and weir it is found that (Cd) inversely proportional with (y1/p) and directly proportional with (y1/h &p/h) and a maximum (Cd ) can be reached maximum for both acute and obtuse V-notch angle. Suitable equations for discharge coefficient are obtained for different apex angle, then the predicated discharge coefficient from the equations were plotted against the calculated value with coefficient of determination (R2=0.9) and it was found to be good.
Keywords: Broad Crested Weir, Side Weir, V-Notch