樋管(ひかん)とは、洪水時に施設側に川の水が逆流しないように、水路に設置されたゲートです。見た目は水門に似ていますが、水門は小規模で、堤防の中に水路が埋設されています。

A sluicing outlets is a gate installed in a waterway to prevent river water from flowing back to the facility side during floods. It looks like a water gate, but the gate is small and has a channel buried inside the embankment.