Scour Downstream Oblique V-notch Weir

Scour in bed material downstream weirs is considered the most unfavorable process which threats the overall stability of the weir. Weirs with oblique angle in the horizontal plan will affect the scour profile downstream the structure and may reduce it. The objective of this paper is to investigate the effect of oblique weir angle on the scour profile. Furthermore, the effect of V-notch angle on the scour profile will be studied. In order to achieve that, laboratory experiments were carried out to test four weirs models of different V-notch angle 30°, 60°, 90° and 120°. Experiments were conducted at three different Froude numbers and four different oblique angles of the weir (0 (normal to the flow), 5, 10 and 15°). The results showed that scour parameters (maximum scour depth and volume of scour) can be decreased by placing the V-notch weir with small oblique angle. The changes in scour parameters for V-notch angles 30, 60 and 90 were not significant while it decreased significantly by using 120° weir. By increasing oblique weir angle, maximum scour depth/length will be increased significantly adjacent to one of the walls. Higher oblique angles will cause the flow to hit the channels sides and affect the structure walls. Empirical equations defining maximum scour depth/length and scour hole with different variables were developed.