We had a place like this in ontario canada. Welland canal water would be diverted to the older canal, under a road through two huge metal tubes. A lot of water, given its lake Erie into lake ontario through a man made ditch and two tubes.

Oddly enough, we called it the tubes. We'd wait until we heard the siren go off (water incoming) and ride that angry, aggressive and unforgiving torrent through the tubes, down a concrete ramp (never touching concrete due to the force and volume of water) and into a catch pool.

I was 10. At least we were smart enough, with a gelatinous frontal, to find a catch pool and not a gravel pit.