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Back to spillwaysSpillways & Outlets - Scour

A Scour and a water supply pipe

A Scour and a water supply pipe
running through a tunnel under a dam

The scour is an outlet pipe or tunnel that runs through the bottom of the dam. It is usually large because of its uses.

The scour can be used in an emergency, for example, when a dam is damaged and poses a threat of imminent collapse. It can be opened to let water out of the reservoir very quickly.

The scour is also opened to flush sediment out of a reservoir when too much has collected behind the dam. The fast flowing water carries the sediment through the scour and downstream.

Valves or gates are used to control the flow of water through the scour.