Water in a canal 30 dm wide and 12 dm deep is flowing with a velocity of 10 km/h. How much area will it irrigate in 30 minutes if 8 cm of standing water is required for irrigation? (Ans: 225000 cu. m)
Ans: Width of canal = 30 dm = 3m
Depth of canal = 1.2 m
Velocity = 10 km / h = 10000 m/h
Length of water column is formed in 30 min = 10000 x 1/2 = 5000 m
Let xm^{2} of area be irrigated => x × 8/100 = 5000 × 1.2 x 3
=> x = 225000 m^{2}