Pressure

The Lagan weir allows the pressure of the river to be released so that there is no deluge. 
Completed in 1994, the weir is a series of massive steel barriers which are raised as the tide retreats to keep the river at an artificially constant level. In the event of a dangerously high tide, the weir also acts as a tidal barrage and can be used to protect the city from flooding.
This is planning in detail for what we know will happen. It doesn't stop the rise of water, the pressure.. But it redirects it away from harm.
Sometimes we need to have pressure.valves....People , places, activities which help us when pressure comes to our door.. For it will.