UK Environment Agency Flood Monitoring
eafm integration offers integration with the UK Environment Agency Flood Monitoring API to provide sensors for nearby water levels. Combined with Home Assistant notifications, you could give yourself a warning if a nearby river was likely to flood your local cycle path or the only road out of your village.
The UK Environment Agency Flood Monitoring only provides data for England - Northern Ireland, Scotland and Wales have their own flood agencies.
Home Assistant offers the flood monitoring integration through Settings -> Devices & Services -> Environment Agency Flood Gauges.
You will be prompted to select a monitoring station. You can find the name of nearby monitoring stations on the Flood information service website.
Sensors for that monitoring station should then appear in your Home Assistant instance.