How do locals protect themselves from floods, living in a flood zone?

you generally get a lot of warning before a flood, and you learn to gauge how much rain will cause a flood, be ready to move any low objects higher, cars etc, any houses in flood reach are raised, so you have to be pretty unlucky to get water in your house. Floods that get to the height needed to invade your house are a lot rarer than people think

And...it's not the depth of the water on the causeway but the speed at which it's travelling that will do the most damage.

It always helps to be aware of the tides. High tides and king tides with heavy rain in between is always a problem. Know your tides and keep an eye on the river!