Question

Given below are two statements: one is labeled as Assertion A and the other is labeled as Reason R.
Assertion A: A low drainage density reflects good drainage conditions in the catchment.
Reason R: Poor conditions are observed in areas where soils are resistant to erosion.
In the light of the above statements, choose the most appropriate answer from the options given below.

• A. Both A and R are correct and R is the correct explanation of A
• B. Both A and R are correct but R is NOT the correct explanation of A
• C. A is correct but R is not correct
• D. A is not correct but R is correct

Hint:

Remember: High permeability leads to low drainage density. This relationship is commonly asked in watershed and geomorphology exams.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Drainage density is the total length of streams per unit area of a watershed. It indicates the efficiency of drainage and is influenced by permeability, vegetation, rainfall, and geology.

Step 2: Detailed Explanation:
Assertion A: Correct.
Low drainage density generally occurs in permeable soils with high infiltration. Such catchments experience less surface runoff and better groundwater recharge, indicating favorable drainage characteristics.
Reason R: Incorrect.
Soils that are resistant to erosion usually produce better, not poorer, watershed conditions because they reduce sediment yield and channel development. Therefore, the reason is scientifically incorrect and cannot explain the assertion.

Step 3: Final Answer:
Assertion A is true, but Reason R is false. Hence, the correct answer is (C).