Question

The gross commanded area for a distributary area is 10,000 hectare. 75% of which can be irrigated. The intensity of irrigation for the Rabi season is 60%. If the average duty at the head of the distributary is 2,500 hectares per cumec for the Rabi season, determine the discharge required at the head of distributary from average demand consideration. 
1. 5 cumec
2. 1.8 cumec
3. 10 cumec
4. 25 cumec
5. 34 cumec

Answer 1

Correct Answer - Option 2 : 1.8 cumec

Concept:

Area required to be irrigated = Intensity of irrigation × Culturable Command Area (CCA)

Design Discharge \(= \frac{{{\rm{Area\;to\;be\;irrigated}}}}{{{\rm{Average\;duty}}}}\)

Given: GCA = 10,000 hectare

Calculation:

CCA = 75% of GCA \(= \frac{{75}}{{100}} \times 10,000 = 7500{\rm{\;hectare}}\)

I.O.I = 60%

Average duty = 25000 hectares per cumec

To Find: Design discharge =?

Area required to be irrigated = 0.6 × 7500 = 4500 hectare

Design discharge \(= \frac{{4500}}{{2500}} = 1.8{\rm{\;cumec}}\)