Question

Which one of the following dams resists external forces by its own weight?

• A. Earthen dam
• B. Gravity dam
• C. Storage dam
• D. Detention dam

Answer 1

The Correct Option is B

A gravity dam is a type of dam that resists external forces primarily through its own weight, ensuring stability and effective water control. The question asks which dam type resists external forces by its weight, and the correct answer is the "Gravity dam". Below is the explanation:

Explanation:

The design and functioning of various types of dams differ based on how they withstand the forces acting on them:

1. Gravity Dam:

• A gravity dam relies on its mass to hold back water. Its weight provides the resistance against the horizontal hydrostatic pressure exerted by the water in the reservoir. The structure's stability comes from the balance between the dam's weight and the water pressure against it. These dams are usually made of concrete or stone.
• The design requires the wider base to ensure that the force of water against the dam does not overturn or slide the dam downstream.

2. Other Dam Types:

• Earthen Dam: Primarily built with earth materials like soil, clay, or rock, and resists forces through weight, but they are fundamentally different due to their construction materials and seepage control mechanisms.
• Storage Dam: Holds water for irrigation, human consumption, etc., but is not specifically defined by how it resists hydrostatic pressure and can be a type of gravity, earthfill, or arch dam.
• Detention Dam: Designed to temporarily catch and store water to prevent floods and is not defined by structural resistance mechanisms like a gravity dam.

In conclusion, a gravity dam is mainly constructed to withstand the pressure from the water it holds back through its substantial weight, making it the correct answer to the question.