Question

In mole drainage system, mole drains are commonly installed at depths between

• A. \(0.2\) and \(0.3\,m\)
• B. \(0.4\) and \(0.7\,m\)
• C. \(0.8\) and \(1.0\,m\)
• D. \(1.1\) and \(1.3\,m\)

Hint:

Mole drainage is useful in heavy clay soils for removing excess subsurface water.

Answer 1

The Correct Option is B

Concept:
Mole drainage is a subsurface drainage method used in heavy clay soils.

Step 1: In mole drainage, a bullet-shaped mole plough creates an unlined channel below the soil surface.

Step 2: These channels help remove excess water from heavy soils.

Step 3: The depth should be sufficient to drain water but not too deep to reduce effectiveness.

Step 4: Mole drains are commonly installed at depths between: \[ 0.4\text{ and }0.7\,m \]

Step 5: Hence, the correct answer is \(0.4\) and \(0.7\,m\). \[ \boxed{0.4\text{ and }0.7\,m} \]