2014 Flood Safety Awareness Week is March 16th - 22nd
 

--- Today’s topic is...Flood Hazards ---

 

Floods occur Nationwide and are the deadliest weather-related killers in the United States. From river flooding...to urban flooding...to flash flooding...flooding can be life-threatening. Therefore, you need to keep informed of developing flood situations and be prepared to take quick action to avoid danger.

                                                                                                                                                         Flooding near Bismarck

 


 Flood Definitions

- A flood is defined as any high flow, overflow, or inundation by water which causes or threatens damage. This usually occurs 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.).

- A
flash flood is defined as a rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level. Ongoing flooding can intensify to flash flooding in cases where intense rainfall results in a rapid surge of rising flood waters. Commonly it occurs within 6 hours of a heavy rain event. However, flash floods can also occur within a few hours or even minutes if a dam or levee fails, following a sudden release of water held by an ice or debris jam, or rapid poding of water caused by torrential rainfall.
 


Flash flooding from levee breach on the Embarras River


 Flood Products

- A flood watch indicates that conditions are favorable for flooding to develop. Be prepared to move to higher ground. Listen to NOAA Weather Radio, commercial radio, or television for additional information.

- A
flood warning means that flooding is occurring or will occur soon. If advised to evacuate, do so immediately.

- A
flash flood warning means that flash flooding is occurring or imminent. Move to higher ground immediately. Flash Floods develop much quicker than river floods.


River Flooding and Associated Flood Categories

River flooding occurs when rivers rise and overflow their banks, inundating areas that are normally dry. With river flooding, the NWS uses different categories to convey the expected flood severity at each of our river forecast points. These flood categories are: Minor, Moderate, and Major. Each category has a definition based on property damage and public threat to areas along a particular reach of river upstream and downstream from the forecast point. These established categories are closely coordinated by the local NWS office, the servicing River Forecast Center (RFC), and other Emergency and Public Officials.

  

Minor Flooding is when minimal or no property damage is expected to occur, but the flooding could possibly cause some public threat or inconvenience.

 

Moderate Flooding is when some inundations of structures and roads near streams will occur. Some evacuations of people and/or a transfer of property to higher elevations are necessary.

 

Major/Record Flooding is when there is extensive inundation of structures and roads along with possible significant evacuations of people and/or transfer of property to higher elevations.


 Other Flood Hazards

- Snowmelt: Flooding due to snowmelt most often occurs in the spring when warming temperatures quickly melt the snow. The water runs off the still partially frozen or already saturated ground into nearby streams and rivers, causing them to rapidly rise and sometimes overflow their banks.


- Ice and Debris Jams:
A backup of water into surrounding areas can occur when a river or stream is blocked by a build-up of ice or other debris.


- Dam Break and Levee Failure:
A break or failure can occur with little to no warning. Most often they are caused by water overtopping the structure, excessive seepage through the surrounding ground, or a structural failure.



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.  Check out these important flood websites for more information...

 

NWS AHPS: http://water.weather.gov/ahps

Flood Safety Awareness: http://www.floodsafety.noaa.gov

TADD:
http://www.nws.noaa.gov/floodsafety/tadd.shtml

NWS:
http://www.weather.gov

Be a force of nature:
http://www.nws.noaa.gov/com/weatherreadynation/force.html


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.