Q.89 The gross command area for a distributary is 10,000 ha and 80% of this is culturable. The intensity of irrigation is 50% for wheat and 30% for rice. Determine the total area cultivated by wheat and rice.
- A4000 ha
- B2400 ha
- C6400 haCorrect
- D8000 ha
Solution
Concept
Area under each crop = Culturable Command Area (CCA) × intensity of irrigation for that crop.
Formula
CCA = 0.8 × GCA; Area of crop = CCA × (Intensity/100)
Step-by-step solution
1. GCA = 10,000 ha 2. CCA = 80% of GCA = 0.8 × 10,000 = 8,000 ha 3. Wheat area = 50% of CCA = 0.5 × 8,000 = 4,000 ha 4. Rice area = 30% of CCA = 0.3 × 8,000 = 2,400 ha 5. Total area = 4,000 + 2,400 = 6,400 ha
Explanation
Intensity of irrigation is always applied to the culturable command area (CCA), not the gross command area. First find CCA = 8,000 ha. Then wheat = 4,000 ha and rice = 2,400 ha, so the total is 6,400 ha.
Why the other options are wrong
A: 4000 ha is only the wheat area. B: 2400 ha is only the rice area. D: 8000 ha is the CCA, not the cropped area.
Shortcut
Total = CCA × (sum of intensities) = 8,000 × 0.8 = 6,400 ha
Common mistake
Applying the intensity to the GCA (10,000 ha) instead of the CCA (8,000 ha).
Correct answer: C) 6400 ha