Match the following lists :
| List-I (Type of surface) | List-II (Value of coefficient of runoff) |
|---|---|
| P.Wooded areas | 1.0·70 – 0·95 |
| Q.Gravel roads and walks | 2.0·15 – 0·30 |
| R.Macadamized Roads | 3.0·01 – 0·20 |
| S.Watertight roof surfaces | 4.0·25 – 0·60 |
Select the correct answer using the code given below :
- A2 3 1 4
- B3 2 4 1Correct
- C3 1 2 4
- D4 1 2 3
Solution
Concept
Runoff coefficients for different surfaces
Formula
Q = C i A
Step-by-step solution
1. Wooded areas absorb most rain: C = 0.01–0.20 → 3. 2. Gravel roads and walks: 0.15–0.30 → 2. 3. Macadamized roads: 0.25–0.60 → 4. 4. Watertight roofs: 0.70–0.95 → 1.
Explanation
The more impervious a surface, the higher its runoff coefficient.
Why the other options are wrong
The other codes give a watertight roof a low coefficient.
Shortcut
Roof highest; woods lowest.
Correct answer: B) 3 2 4 1