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sluice gate; water gate; flood gate
大雨のため、水門を開けた。
Due to heavy rain, they opened the sluice gate.
古い水門が台風で壊れてしまった。
The old sluice gate was damaged by the typhoon.
ダムの水位が上昇したため、水門を開けて放水した。
As the dam's water level rose, they opened the sluice gate to release water.