Forecasters issue a coastal flood watch when coastal flooding is possible within 12-36 hours. A coastal flood warning is issued when coastal flooding is occurring, is imminent, or is expected within the next 12 hours. A warning is sometimes issued 24 hours in advance when is it very likely that coastal flooding will occur or when a longer amount of time is needed for evacuation or other public response.
If a flood or flash flood watch is issued –
• Ensure that all staff members are aware of evacuation routes
• Move valuable collections to upper shelves
• Ensure that all collections are at least 4 inches off the floor.
• If necessary and possible, relocate collections to other locations in the library.
• Ensure that flashlights and fresh batteries are available. (Brandi)
• Ensure that battery powered radios with weather band (and fresh batteries) are available. (Brandi)
• Perform a controlled shutdown of the computer system and put all computers on the desk. (Library Staff)
• If the local authorities instruct you to do so, turn off all utilities at the main power switch. (Maintenance)
• Be prepared to evacuate at any time.
Flooding (Floodplain, River, Lake, and/or Stream)
Flooding is very common in the United States and can be caused by a variety of events. Flooding often develops over a number of days, as a result of prolonged heavy rain or melting snows that create high river, stream, or reservoir levels. In winter, ice jams in rivers can also contribute to flooding, stopping the river’s flow. Other factors that can make conditions worse are frozen ground (which cannot absorb as much water) and wet or saturated soil. Urban areas, and areas with many buildings and parking lots, may also be at risk of flooding, since there is less soil to absorb the water and storm drains may get overloaded. Flooding can be extremely dangerous; even shallow floodwaters can sweep away cars or people.
A floodplain is defined as a low-lying area near a stream or river that becomes flooded during heavy rains. The terms “500-year-flood” and “100-year-flood” are sometimes used. A 500-year-flood is so large and unusual that it would normally happen only every 500 years. However, it is more accurate to say that each year there is a one in 500 chance of a 500-year-flood occurring (e.g., if a 500-year-flood occurred, it would be possible for another to occur the next year).
Flash flooding is particularly dangerous, as it occurs very quickly with little warning. Flash flooding occurs most often from storms that produce large amounts of rain in a short time, but can also be caused by a river ice jam, or by a catastrophic event such as a dam failure or a tsunami following an earthquake. A flash flood can cause severe damage, destroying buildings and bridges, uprooting trees, etc.
There are a number of flood watches and warnings issued by forecasters. A flood watch is issued when water levels or other conditions indicate that flooding is possible in the given time period. A flood warning is issued when a flood is occurring or is imminent. In the latter case, time and location is usually provided, and orders are given to evacuate vulnerable areas. A flash flood watch is issued when flash flooding is possible in the given time period. A flash flood warning is issued when flash flooding is occurring or is imminent.
Preventive actions to reduce the risk of damage from flooding –
• Consider constructing barriers, such as levees, to protect your building and property.
• Purchase flood insurance. Flood insurance is guaranteed through the National Flood Insurance Program (NFIP) http://www.fema.gov/nfip/, administered by the Federal Emergency Management Agency. Be aware that it normally takes 30 days after purchase for a flood insurance policy to go into effect, so purchasing insurance at the last minute is not possible.
• If flooding occurs frequently in your area, stockpile supplies for protecting your building, including plywood, plastic sheeting, lumber, nails, hammer, saw, pry bar, shovels, and sandbags.
• Be aware of the locations of nearby storm sewers and water mains.
• Install sewer backflow valves (this keeps flood waters from backing up in sewer drains).
• Identify any stored hazardous materials or other chemicals that could be flooded. Move or raise them.
• Consider making changes to your building to reduce potential damage from flooding. Remember that a licensed contractor must make any changes. Potential changes (explained in more detail on FEMA’s web site
http://www.fema.gov/hazards/floods/whatshouldidoprotect.shtm include –
• Raising your electrical system components
• Adding a waterproof veneer to the exterior of your building
• Anchoring your fuel tank(s)
• Raising or flood proofing your HVAC equipment
• Poviding openings in foundation walls that allow floodwaters in and out, thus avoiding collapse
• Building and installing flood shields for doors and other openings (have your building evaluated to ensure it can handle the forces)
• Put together a disaster kit (drinking water, canned/no-cook food, non-electric can opener, first aid kit, battery-powered radio with weather band and alert, flashlights and extra batteries). Check all items every six months and replace any expired items (e.g., water, food, batteries).
Coastal Flooding
Institutions located near the ocean are at risk of coastal flooding, which refers to the inundation of land near the coast by seawater, over and above the usual tides. Coastal flooding is usually generated by storms with strong winds that drive the seawater inland (this is known as a storm surge). Such storms are most often hurricanes, tropical storms, or nor’easters.
Forecasters issue a coastal flood watch when coastal flooding is possible within 12-36 hours. A coastal flood warning is issued when coastal flooding is occurring, is imminent, or is expected within the next 12 hours. A warning is sometimes issued 24 hours in advance when is it very likely that coastal flooding will occur or when a longer amount of time is needed for evacuation or other public response.
Coastal flooding levels are categorized according to the amount the water rises above the normal tide level. Minor flooding does not do any significant damage to homes or buildings and causes only minor beach erosion. Moderate flooding can threaten lives and property, and may flood some roads and cause moderate beach erosion. Major flooding is a serious threat and will likely cause numerous flooded roads and major damage to homes and businesses, along with major beach erosion. Evacuation of people living or working near the coast is usually required.
If your institution is located near the coast –
• Consider constructing barriers, such as levees, to protect your building and property.
• Purchase flood insurance. Flood insurance is guaranteed through the National Flood Insurance Program (NFIP) http://www.fema.gov/nfip/, administered by the Federal Emergency Management Agency. Be aware that it normally takes 30 days after purchase for a flood insurance policy to go into effect, so purchasing insurance at the last minute is not possible.
• If flooding occurs frequently in your area, stockpile supplies for protecting your building, including plywood, plastic sheeting, lumber, nails, hammer, saw, pry bar, shovels, and sandbags.
• Install sewer backflow valves (this keeps flood waters from backing up in sewer drains).
• Identify any stored hazardous materials or other chemicals that could be flooded. Move or raise them.
• Consider making changes to your building to reduce potential damage from flooding. Remember that any such changes must be made by a licensed contractor. Potential changes (explained in more detail on FEMA’s web site
http://www.fema.gov/hazards/floods/whatshouldidoprotect.shtm) include –
• raising your electrical system components
• adding a waterproof veneer to the exterior of your building
• anchoring your fuel tank(s)
• raising or flood proofing your HVAC equipment
• Provide openings in foundation walls that allow floodwaters in and out, thus avoiding collapse
• Build and install flood shields for doors and other openings (have your building evaluated to ensure it can handle the forces)
• Put together a disaster kit (drinking water, canned/no-cook food, non-electric can opener, first aid kit, battery-powered radio with weather band and alert, flashlights and extra batteries).