Floods are one of the most common hazards on Earth and have claimed millions of lives in the past 100 years. Flooding can be triggered by heavy rainfall, tsunami events, high astronomical tides, snow melt, ice jams, prolonged strong onshore winds, or a failure of dams/levees to trigger. Flash floods are caused by excessive rainfall over a short period of time and are generally characterized by outpouring that sweeps through river beds, canyons, and streets.

Related Hazards

• High water
• Dangerous moving debris caught up in the flow of water
• Landslides and mudslides
• Contaminants carried by flood waters
• Falling trees or other objects such as high-voltage power lines due to saturated ground

Precautions

• Be familiar with the typical rainfall pattern in your area, including the amount and duration of rainfall.
• Check the “lay of the land” at your home, and in areas that you visit frequently. If the surrounding land is higher than your location, there is a risk of flooding.
• Look for flow paths from previous landslides; this will provide a reasonable estimate of where mudslides and landslides are likely to occur in the future.
• Even light rain can produce flooding if it continues for a long time and if the ground cannot absorb the rainfall fast enough.
• Be aware of the location of dams and retaining basins in your area, and report any suspected dangerous activity.

What to Do During a Flood

• Check weather monitoring resources frequently, and take all watches and warnings seriously.
• When you know or suspect that flood water is coming your way, move to higher ground.
• Avoid driving onto water-covered roads, even if the water depth seems low.
• Do not walk or swim in flood water, and be watchful for dangerous debris.
• Leave the handling of downed power lines to professionals; set up a “do not cross” perimeter around the downed line and the surrounding wet zone.

Resources

NOAA National Weather Service Flood Safety

PDC Weather Wall

NOAA Turn Around, Don't Drown