Flood Safety Awareness Week--Flood Hazards

It floods somewhere in the United States or its territories nearly every day of the year. Flooding causes more damage in the U.S. than any other weather-related event, with an average of eight billion dollars a year and an average of ninety-five fatalities per year in the past thirty years. Flooding can occur in any of the fifty states or U.S. territories at anytime of the year, sometimes very quickly. Being prepared in advance and knowing a few flood safety tips will help you and your family survive a flood if it happens in your area.

A flood is defined as any high flow, overflow, or inundation of water that causes or threatens damage. Flooding can occur with prolonged rainfall over several days, intense rainfall over a short period of time, or when water from an existing source moves too quickly (i.e., snowmelt, dam break, etc.). Brief descriptions of the various types of flooding you may experience are found below. More information about these flood hazards can be found on the NWS Flood Safety Website at https://www.floodsafety.noaa.gov.

River flooding occurs when rivers rise and overflow their banks inundating areas that are normally dry. The NWS uses different categories to convey the expected flood severity. These categories are:

Minor Flooding

• Usually has minimal or no property damage, but there could be some level of public threat or inconvenience.

Moderate Flooding

• Generally has some inundation of structures and roads near streams and rivers. Some evacuations of people and transfer of property to higher elevations can become necessary with Moderate Flooding.

Major Flooding

• Occurs with extensive inundation of structures and roads. Significant evacuations of people and transfer of property to higher elevations may become necessary.

Record Flooding

• This is flooding which equals or exceeds the highest stage or discharge observed at a given site during the period of record. The highest stage on record is not necessarily above the other three flood categories, especially if the period of record is short.

Flood categories do not exist for all forecast points or flood locations. That doesn't mean they don't flood! Contact the NWS for more information on flood categories.

At any time of year, a storm from over the ocean can bring heavy precipitation to U.S. coasts. Whether such a storm is tropical or not, prolonged periods of heavy precipitation can cause freshwater flooding in coastal areas, as well as farther inland as the storm moves onshore. In addition to the freshwater flood threat, tropical systems and nor'easters can bring the threat of coastal flooding from storm surge.

Storm surge is often the greatest threat to life and property from a tropical cyclone. In the past, large death tolls have resulted from the rise of the ocean associated with many of the major hurricanes that have made landfall. Hurricane Katrina in 2005 is a prime example of the damage and devastation that can be caused by storm surge. At least 1500 people lost their lives during Hurricane Katrina, and many of these deaths occurred directly, or indirectly, as a result of storm surge. 

Understanding the different flood hazards and knowing the actions to take before, during, and afterwards can help you protect your life, the lives of your loved ones, and your property. Prepare now by visiting www.floodsafety.noaa.gov.