It Is Difficult To Guard Against.

River flooding obviously poses a risk to areas close to rivers.

Flash flooding really poses a risk to anywhere open to the sky. So everywhere and anywhere really.

https://www.rt.com/news/529627-germany-minister-rejects-failure-flood-deaths/

Also didn't a lot of people die in their basements?

Which hardly seems the most logical reaction to rising flood waters. Looking for lower ground.