Translation guide
A structure used to release excess water from a dam, reservoir, or canal. In Japanese, the most common term is 余水吐き, but other technical terms exist depending on context.
The most common way to refer to a spillway in everyday or general contexts.
The standard term for a spillway. Literally 'excess water spout'. Used in general and technical contexts.
Water is gushing out from the dam's spillway.
Often used for larger-scale spillways or discharge channels. Can also mean 'drainage canal' or 'discharge channel'.
The dam's spillway was opened due to heavy rain.
A synonym for 余水吐き, used in engineering contexts. Literally 'excess water channel'.
The design of the spillway requires meticulous attention.
Specifically refers to an emergency spillway used during floods or extreme conditions.
A spillway that allows water to overflow when the water level exceeds a certain point.
A spillway where water flows over a side weir into a channel parallel to the dam.
Side channel spillway. A technical term used in dam engineering.
This dam uses a side channel spillway.
余水吐き is the most direct translation for 'spillway' and is used specifically for dam overflow structures. 放水路 can refer to any water discharge channel, including spillways, but also drainage canals and floodways. In dam contexts, 余水吐き is more precise.
In casual conversation, 余水吐き may not be widely known. If explaining to a non-specialist, you can describe it as ダムの水を逃がすところ (the place where water is released from the dam).
Construction of the emergency spillway is being rushed.