Question

Arrange the followings in terms of their lower to higher value of run off coefficients for silt type of soil at 10 – 30% slope.
(A) Cultivated land
(B) Pasture land
(C) Forest land
Choose the correct answer from the options given below :

• A. (A), (B), (C)
• B. (A), (C), (B)
• C. (C), (B), (A)
• D. (B), (C), (A)

Hint:

Vegetation cover acts as a natural barrier to runoff. Therefore, more dense forest cover always results in a lower runoff coefficient than bare or cultivated land.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The runoff coefficient ($C$) is the ratio of runoff to rainfall.
A higher runoff coefficient indicates that a larger fraction of rainfall becomes surface runoff, which is highly dependent on vegetation cover, soil type, and slope.
Detailed Explanation:
Let us analyze the impact of land cover on runoff for a silt soil with a steep slope ($10\%$-$30\%$):
- Forest land (C): Dense canopy, leaf litter, and deep root networks maximize rainfall interception and soil infiltration, resulting in the lowest runoff coefficient.
- Pasture land (B): Grass cover provides moderate protection against raindrop impact and slows down surface flow, resulting in an intermediate runoff coefficient.
- Cultivated land (A): Often bare, disturbed, or tilled, offering the least protection against soil erosion and surface sealing. This leads to the highest runoff coefficient.
Arranging the lands from lower to higher runoff coefficient:
\[ \text{Forest land (C)} \rightarrow \text{Pasture land (B)} \rightarrow \text{Cultivated land (A)} \] This corresponds to the sequence: (C), (B), (A).

Step 2: Final Answer:
The correct sequence matches Option (C).