Question

Which of the following statements regarding hydrologic soil groups are correct?
(A). Group-A soils having high runoff potential.
(B). Group-A soils having high infiltration rates.
(C). Group-C soils having low infiltration rates.
(D). Group-B soils having very low infiltration rates.
(E). Group-D soils having moderately low runoff potential.

Choose the correct answer from the options given below:

• A. (A), (B), (C) and (E) only.
• B. (B) and (C) only.
• C. (B), (C) and (E) only.
• D. (B), (C) and (D) only.

Hint:

Remember the progression:
- Group A: High Infiltration \(\implies\) Low Runoff.
- Group D: Low Infiltration \(\implies\) High Runoff.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The USDA Natural Resources Conservation Service (NRCS) classifies soils into four Hydrologic Soil Groups (A, B, C, D) based on their runoff-producing characteristics and minimum infiltration rates.

Step 3: Detailed Explanation:
Let us review the four soil groups:
1.

Group A: Soils with low runoff potential and high infiltration rates even when thoroughly wetted. These are typically deep, well-drained sands or gravels. Thus, (B) is correct and (A) is incorrect.
2.

Group B: Soils with moderate infiltration rates and moderately low runoff potential. Thus, (D) is incorrect (as it states "very low").
3.

Group C: Soils with low infiltration rates and moderately high runoff potential. These contain layers that impede downward movement. Thus, (C) is correct.
4.

Group D: Soils with high runoff potential and very low infiltration rates. These are highly plastic clays or soils with a permanent high water table. Thus, (E) is incorrect.
Therefore, only statements (B) and (C) are correct.

Step 4: Final Answer:
The correct option is 2, which corresponds to (B) and (C) only.