Question

Provision of horizontal berms at suitable vertical intervals may be provided in the downstream face of an earthen dam in order to _________________

(a) allow the movement of cattle

(b) allow the inspection of vehicles to move

(c) reduce the erosion caused by the flowing rainwater

(d) increase the erosion

This question was addressed to me in an interview for internship.

This is a very interesting question from Design Criteria of Earth Dams topic in chapter Earthen and Rock Fill Dams of Irrigation Engineering

Answer 1

The correct choice is (c) reduce the erosion caused by the flowing rainwater

The explanation is: The provision of berms serves the following purposes –

It behaves like a good lining for reducing losses and leakage.

They provide protection against erosion and breaches due to wave action.

They help the channel to attain regime conditions as they help in providing a wider waterway.

It can be used as borrow pits for excavating soil to be used for filling.