Flood / Heavy Rain
Rainfall accumulation and flash-flood risk
What is it?
Flooding follows when rain falls faster than ground and drainage can absorb it. Flash floods can develop in minutes; river floods build over days. Water depth and speed are deceptive — most flood deaths involve vehicles.
How we measure it
Forecast daily rainfall accumulation (mm) from Open-Meteo, plus GloFAS river-discharge context where a river cell exists.
Daily rainfall guide (IMD classification)
- < 15 mmLightRoutine wet weather
- 15–64 mmModeratePuddling, slow drains, slippery roads
- 65–115 mmHeavyLocal waterlogging; underpasses flood
- 116–204 mmVery heavyUrban flooding likely; streams rise fast
- 205+ mmExtremely heavySerious flooding potential
Within safe range
Under ~65 mm/day, drainage in most cities copes; allow extra travel time and watch for aquaplaning.
Beyond the range
Above ~115 mm/day, water accumulates faster than it drains: 15 cm of moving water can knock an adult down, 30 cm floats most cars, and 60 cm carries them away. Floodwater also hides open drains and carries contamination.
Precautions
- Never drive or walk through moving water — 'Turn around, don't drown'.
- Know your local low points: underpasses, causeways, basement exits.
- Move valuables and vehicles up before forecast very-heavy rain.
- Keep drains around your building clear ahead of the season.
- Avoid contact with floodwater; treat any that touched food or wounds as contaminated.