A flood is when water overflows onto land that is normally dry, covering streets, fields, or buildings instead of staying in rivers, lakes, or the sea.

Quick Scoop: What is a flood?

  • A flood is an overflow of water that submerges normally dry land.
  • It can come from rivers, lakes, or the sea when they rise above their usual banks.
  • Heavy rain, storms, fast snowmelt, or failures of dams and levees can all trigger floods.
  • Floodwater can be shallow or deep enough to reach rooftops, and even a few inches can cause serious damage.

Main ways floods happen

  • River and lake flooding (fluvial/riverine): Rivers and lakes swell and spill over their banks into nearby land.
  • Coastal flooding: Ocean water is pushed inland by storms, hurricanes, or unusually high tides.
  • Flash floods: Water rises very quickly after intense rain, often with little warning, and can become dangerous in minutes.
  • Urban/areal flooding: Rainwater builds up in cities or on saturated ground when drains, soil, or drainage systems cannot absorb it fast enough.

Why floods matter

  • They are among the most common natural disasters worldwide, affecting homes, roads, farms, and essential services.
  • Floods can damage buildings and infrastructure, contaminate drinking water, and threaten lives.
  • Knowing “what is a flood?” is the first step to understanding warnings, preparing emergency kits, and staying safe when water starts to rise.

Information gathered from public forums or data available on the internet and portrayed here.