Direction: For a catchment, the S-curve (or S-hydrograph) due to a rainfall of intensity 1 cm/hr is given by Q = 1 – (1 + t) exp (–1) (t in hr and Q in m³/s).
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What is the area of the catchment ?
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- 0.01 km²
- 0.36 km²
- 1.00 km²
- 1.28 km²
Correct Option: B
Q = 1 – (1 + t)e–t
Saturation discharge for S-curve will be at t → ∞
Q = limt→∞ (1 – (1 + t) e-t)
= 1 – (1 + ∞)e∞ = 1 m³/s
Saturation discharge = Rainfall intensity × Catchment area
1 × 60 × 60 = 1 × 10–3 × Area
∴ Catchment area = 360 × 10³ m² = .36 km².
