Question

Which one of the following equations represents the downstream profile of Ogee spillway with vertical upstream face? [(x, y) are the coordinates of the point on the downstream profile with origin at the crest of the spillway and $H_d$ is the design head].

• A. $\frac{y}{H_d}=-0.5{\left(\frac{x}{H_d}\right)}^{1.85}$
  
• B. $\frac{y}{H_d}=-0.5{\left(\frac{x}{H_d}\right)}^{1/1.85}$
  
• C. $\frac{y}{H_d}=-2.0{\left(\frac{x}{H_d}\right)}^{1.85}$
  
• D. $\frac{y}{H_d}=-2.0{\left(\frac{x}{H_d}\right)}^{1/1.85}$
  

Answer 1

The correct option is A $\frac{y}{H_d}=-0.5{\left(\frac{x}{H_d}\right)}^{1.85}$


For a spillway having a vertical upstream face the downstream crest is given by the equation

$x^{1.85}=-2H_d^{0.85}y$

$x^{1.85}=-2\frac{H_d^{1.85}}{H_d}.y$

$\left(\frac{y}{H_d}\right)=-0.5{\left(\frac{x}{H_d}\right)}^{1.85}$