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

Step 1: Define the runoff coefficient.
The runoff coefficient is the part of rainfall that flows away over the surface instead of soaking into the ground. It is a number between 0 and 1.

Step 2: Link soil type to the value.
A soil that lets little water soak in produces more surface flow, so it has a higher runoff coefficient.

Step 3: Look at clay.
Clay has very tiny particles packed tightly, so water cannot soak through easily. Its infiltration is very low.

Step 4: Predict the value.
Since most rain runs off clay rather than soaking in, the coefficient must be high.

Step 5: Match with the options.
Low ranges like 0.05 to 0.20 suit sandy soils. The high range 0.55 to 0.82 fits clay.

Step 6: Conclusion.
The runoff coefficient for clay soil is about 0.55 to 0.82.
\[ \boxed{0.55 \text{ to } 0.82} \]