Anywhere it rains, it can flood. A flood is a general and temporary condition where two or more acres of normally dry land or two or more properties are inundated by water or mudflow. Many conditions can result in a flood: hurricanes , overtopped levees, outdated or clogged drainage systems and rapid accumulation of rainfall.
Just because you haven't experienced a flood in the past, doesn't mean you won't in the future. Flood risk isn't just based on history, it's also based on a number of factors: rainfall, river-flow and tidal-surge data, topography, flood-control measures, and changes due to building and development.
Flood-hazard maps have been created to show different degrees of risk for your community, which help determine the cost of flood insurance. The lower the degree of risk, the lower the flood insurance premium
What Causes Flood
More than a third of our nation’s dams are already 50 years old. About 14,000 of those dams pose a “high” or “significant” hazard to life and property if failure occurs. There are also about 2,000 "unsafe" dams in the United States and in almost every state. So, while dams are built not to fail, they do.
Dams can fail with little warning. Intense storms may produce a flood in a few hours or even minutes for upstream locations. Flash floods can occur within six hours of the beginning of heavy rainfall, and dam failure may occur within hours of the first signs of breaching. Other failures and breaches can take much longer to occur, from days to weeks, as a result of debris jams, the accumulation of melting snow, build up of water pressure on a dam with (unknown) deficiencies after days of heavy rain, etc. Flooding can also occur when a dam operator releases excess water downstream to relieve pressure from the dam.
The risk for dam failure and the potential catastrophic damage it can cause are not shown on the flood maps from the Federal Emergency Management Agency (FEMA). So, while property owners may be aware that they live downstream from a dam, they may not be aware of the true risk. Property owners should consider financially protecting their home, business and/or contents with flood insurance. Many of these homes and businesses may qualify for the low-cost Preferred Risk Policy, with premiums starting as low as $129 for a home and its contents.
There is typically a 30-day waiting period for a policy to become effective, so don’t wait until the next heavy rain. For more information about dams and the risk of living downstream from them, visit:
- FEMA’s National Dam Safety Program
- Living with Dams: Know Your Risk
- U.S. Army Corps of Engineers National Inventory of Dams
- Association of State Dam Safety Officials
- U.S. Society on Dams
- Dam Safety Action
Flash Floods
Flash floods are the #1 weather-related killer in the U.S. since they can roll boulders, tear out trees, and destroy buildings and bridges. A flash flood is a rapid flooding of low-lying areas in less than six hours, which is caused by intense rainfall from a thunderstorm or several thunderstorms. Flash floods can also occur from the collapse of a man-made structure or ice dam.
See a Flash Flood scenario right now.
