An infiltration gallery is used to obtain water from?

WBPSC AE (PWD) 1998

⭕ (a) A well sank in a river bed

⭕ (b) A trench dug in river bed

⭕ (c) Perforated pipe laid in a trench in a river bed

⭕ (d) Impounded reservoir

Explanation: An infiltration gallery is a horizontal perforated pipe system laid in a trench, usually in the river bed. It collects groundwater from an aquifer below the river. This method benefits from natural bank filtration, which significantly reduces the need for extensive water treatment for surface withdrawals.

Infiltration Galleries for Water Extraction

In environmental engineering, infiltration galleries are used to collect relatively clean subsurface water, reducing the need for water treatment. This question checks your understanding of such groundwater collection techniques.

Advantages of Infiltration Gallery:

• Reduces suspended impurities using natural filtration
• Supplies steady groundwater even during dry spells
• Minimizes cost of treatment

Conclusion:

The correct answer is Perforated pipe laid in a trench in a river bed. This method is efficient for municipal water supply systems and commonly used in riverbank aquifers.