True, for not being at risk from flooding from the ocean given elevation (from sea level).

Local flooding: entirely possible. For example, over a few years city X sinks by a cm, because of that in a flood situation there's slightly more flood water. Over a large area that might be quality a few acre-feet of water: that's quite a lot more water.

It's less that the likely hood of a flood increases and more that the severity of a flood increases.