catchment release, valves, etc
One well-knownish drain in Brisbane used to have gates that would close to collect rain-water, and then open to release that rain water to flush out the drain. I'm pretty sure this was because the drain was also used for sewer at the time. These gates aren't a thing anymore.
Your more likely to see/hear a few harmless centimetres of water rushing out of side pipes being released from somewhere unknown. They can be deafening and a few of them have given me a scare in the past
- I like to know all the risks involved, stemming from my anxiety issues and a somewhat strong desire to survive, and since info from water boards is no longer easily accessible I've been searching everywhere.