The discharge through a wholly drowned orifice is given by (where H1 = Height of water (on the upstream side) above the top of the orifice, H2 = Height of water (on the downstream side) above the bottom of the orifice, and H = Difference between two water levels on either side of the orifice)

• A. Q = Cd × bH2 × √(2gh)
• B. Q = Cd × b (H2 - H1) × √(2gh)
• C. Q = Cd × bH × √(2gh)
• D. Q = Cd × bH₁ × √(2gh)

Answer: (B)