- 2072 Asoj · 5 marks
Most efficient of three distributaries
Short answer
Efficiency is measured by duty (A/Q). Distributary-2 has the highest duty of 1000 ha/cumec (area 20000 ha, Q 20 cumec). Distributaries-1 and -3 both have 600 ha/cumec. Therefore, Distributary-2 is most efficient.
Three distributaries are used for irrigation. The details are given below. Find which one is more efficient.
| Distributary-1 | Distributary-2 | Distributary-3 | |
|---|---|---|---|
| Discharge | 15 m³/s | 20 m³/s | 25 m³/s |
| C.C.A | 15,000 ha | 25,000 ha | 30,000 ha |
| Intensity of irrigation | 60% | 80% | 50% |
| Base period | 200 days (cotton crop) | 120 days (wheat crop) | 365 days (sugarcane) |
Idea. The efficiency of a distributary in using water is measured by its duty: the area irrigated per cumec of discharge during the base period. A higher duty means more area irrigated with the same water.
Step 1: Area irrigated . Step 2: Duty . Step 3: Delta (m).
| Area irrigated = CCA x intensity (ha) | Q (cumec) | Duty = A/Q (ha/cumec) | Delta = 8.64B/D (m) | |
|---|---|---|---|---|
| Distributary-1 | 9,000 | 15 | 600 | 2.880 |
| Distributary-2 | 20,000 | 20 | 1000 | 1.037 |
| Distributary-3 | 15,000 | 25 | 600 | 5.256 |
Sample calculation (Distributary-2): ha, ha/cumec, m.
Comparison: duty is 600, 1000 and 600 ha/cumec respectively.
Answer: Distributary-2 is the most efficient (highest duty, 1000 ha/cumec; lowest water per hectare). Distributary-1 and -3 have the same duty, but their delta is high because cotton and sugarcane are long-base-period, high-water crops. The comparison is approximate, as the crops differ.
✓ Answer checked by Claude Opus 5.5 (high effort)
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