I was at a course recently, an old course, and I noticed features like this, not necessarily within the intended confines of play, that served another function....... redirecting surface flow.
Keeping it away from fairways, bunkers and greens and redirecting it toward streams/ditches meant to channel the water to outflow areas.
With all the rain we've had, and continue to have, it seemed like a pretty neat feature, even if it was incorporated into the confines of play.