Water in a river 6m wide and 1.5m deep flows with a speed of 10km/hr. How much area will it irrigate in half an hour if 8cm of standing water is needed?
Use 10,000m2=1Hectare
56.25 Hectares
Volume of water coming out of 6m wide and 1.5m deep canal in 1 hour at a speed of 10,000m/hr
= 6 × 1.5 × 10,000 = 90,000m3
Hence the volume of water coming out in half an hour is = 90,000 × 1/2 = 45,000 m3
Let the irrigated area be a m2
Standing height of water = 0.08 × a = 45000
a = 562500 m2
1 Hectare = 10,000 m2
So, a = 56250010000
= 56.25 hectare