Correct Answer - Option 4 : Cipoletti weir

__Explanation:__

Different types of the weir and their discharge formulas;

**Ogee weir:**

**\(Q = \frac{2}{3}{C_d}L\sqrt {2g} {H^{3/2}}\)**

**Cippoletti weir:**

\(Q = \frac{2}{3}{C_d}L\sqrt {2g} {H^{3/2}}\)

**Drowned weir:**

**\(Q = \frac{2}{3}{C_d}L\sqrt {2g} {\left( {{H_1} - {H_2}} \right)^{3/2}}\)**

**Triangular weir:**

**\(Q = \frac{8}{{15}}{C_d}L\sqrt {2g} \tan \frac{\theta }{2}{H^{5/2}}\)**

Where,

Q = Discharge

L = Length of the weir

H = Depth of water

C_{d }= Coefficient of discharge