Water in a canal 6 m wide and 1.5 m deep, is flowing with a speed of 10 km/h. How much area will it irrigate in 30 minutes, if 8 cm of standing water is needed?

Width of the canal = 6 m

Depth of the canal = 1.5 m

Length of water column per hour = 10 km

Length of water column in 30 minutes or \(\frac{1}{2}\) hour \( = \ \frac{1}{2} \ × \ 10 \ = \ 5000 \) m

Volume of water flown in 30 minutes \(= \ 1.5 \ × \ 6 \ × \ 5000 \ = \ 45000 \) m³

\(\because \) \( 8 \) cm \( = \ \frac{8}{100} \) m

i.e., 0.08 m standing water is desired

\(\therefore \) Area irrigated in 30 minutes

\( = \ \frac{Volume}{Height} \ = \ \frac{45000}{0.08} \ = \ 562500 \) m² or \(56.25 \) hectares