Question

Which one of the following indicates an approximate range of runoff coefficient for a clay soil?

• A. 0.05 to 0.20
• B. 0.55 to 0.82
• C. 0.46 to 0.50
• D. 0.82 to 0.90

Hint:

The runoff coefficient is the fraction of rainfall that becomes surface runoff rather than infiltrating into the ground. Soils with low permeability produce more runoff and therefore have a higher runoff coefficient.

Answer 1

The Correct Option is B

Concept:
The runoff coefficient is the fraction of rainfall that becomes surface runoff rather than infiltrating into the ground. Soils with low permeability produce more runoff and therefore have a higher runoff coefficient.

Step 1:
Clay soil has very fine particles and very low infiltration capacity. Water cannot soak in easily, so a large part of the rainfall flows off as surface runoff.

Step 2:
This means clay soils have a relatively high runoff coefficient. The standard tabulated range for clay (clayey) soils falls around 0.55 to 0.82, which matches the given option.

Answer: Option (2) — 0.55 to 0.82.