Which of the following spillway is least suitable for an earthen dam?

Explanation:

Earth Dams

• These built up by compacting successive layers of earth, using the most impervious materials to form a core, and placing more permeable substances on the upstream and downstream sides.
• Earth and rockfill dams cannot be used as overflow dams. So, a separate spillway has to be provided.

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• The least suited spillway for earthen dams is the Ogee spillway as these are overflown spillways that cannot be constructed on the earthen dam as it will wash away soil and pose other problems also.
• The suitable spillway for earthen dams can be a side-channel spillway as it carried away by a. channel running parallel to the crest.