Direction: Ordinates of a 1-hour unit hydrograph at 1 hour intervals, starting from time t = 0, are 0, 2, 6, 4, 2, 1 and 0 m³/s.
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Catchment area represented by this unit hydrograph is
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- 1.0 km²
- 2.0 km²
- 3.2 km²
- 5.4 km²
Correct Option: D
Total volume of water = area under unit hydrograph
= 60 × 60 × 1 × (0 + 2 + 6 + 4 + 2 + 1 + 0) = 54000 m³
∵ Unit hydrograph, rainfall excess is 1 cm, i.e. 10–2 m.
A × 106 × (1 × 10-2) = 54000 (106 to make it km²)
| ∴ A = | = 5.4 km² | |
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