Floods – Vulnerability Assessment & Risk


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.

Understanding the Flood Vulnerability of Your Area

Changing weather patterns, erosion, and development can affect floodplain boundaries. Flooding can happen anywhere, but certain areas are especially prone to serious flooding. Flood-hazard maps have been created by FEMA at FloodSmart.gov to show different degrees of risk for your community, which help determine the cost of flood insurance.

To help communities understand their risk, flood maps (Flood Insurance Rate Maps, FIRMs) have been created to show the locations of high-risk, moderate-to-low risk and undetermined-risk areas.

Types of Flood Risk Areas

FEMA maintains and updates data through Flood Insurance Rate Maps (FIRMs) and risk assessments. FIRMs include statistical information such as data for river flow, storm tides, hydrologic/hydraulic analyses and rainfall and topographic surveys.

FEMA uses the best available technical data to create the flood hazard maps that outline a community’s flood risk areas. Here are the different flood risk area types:[2]

High-Risk Areas
Special Flood Hazard Area (SFHA)

In high-risk areas, there is at least a 1 in 4 chance of flooding during a 30-year mortgage. All home and business owners in these areas with mortgages from federally regulated or insured lenders are required to buy flood insurance.

Floodplains and areas subject to coastal storm surge are shown as high-risk areas or Special Flood Hazard Areas (SFHAs). Some parts of floodplains may experience frequent flooding while others are only affected by severe storms. However, areas directly outside of these high-risk areas may also find themselves at considerable risk.

SFHAs are defined as the area that will be inundated by the flood event having a 1-percent chance of being equaled or exceeded in any given year. The 1-percent annual chance flood is also referred to as the base flood or 100-year flood.

Insurance note: Flood insurance is mandatory in high-risk areas for most mortgages that are secured by loans from federally regulated or insured lenders.

Moderate-to-Low Risk Areas
Non-Special Flood Hazard Area (NSFA)

In moderate-to-low risk areas, the risk of being flooded is reduced but not completely removed. These areas submit over 20% of NFIP claims and receive one-third of disaster assistance for flooding. Flood insurance isn’t federally required in moderate-to-low areas, but it is recommended for all property owners and renters.

Insurance note: Lower cost, Preferred Risk Policies are often an option in these areas, starting at $129 per year. Flood insurance coverage is not mandated in X zones, but is recommended, as the risk for flood is still very real. Keep in mind that while your property could be designated as moderate-to-low risk, it may still be geographically close to a Special Flood Hazard Area (SFHA).

Undetermined-Risk Areas

No flood-hazard analysis has been conducted in these areas, but a flood risk still exists. Flood insurance rates reflect the uncertainty of the flood risk.

Flood Vulnerability Assessment Questions

To assess your vulnerability to the threat of a Flood to your family and property, perform an assessment to determine if you have knowledge of, are prepared and/or have a plan by answering the following questions:

General All-Hazard Questions:

  • Have you determined the disaster risks in your locale and the hazards that accompany them?
  • Do you know the emergency warning signals and alert notifications used in your community?
  • Have you instructed family members how to shut off water, gas and electricity to your house?
  • Have you made the necessary property preparations to reduce the damage from the hazard?
  • Do you have a backup generator in case of a prolonged power failure?
  • Have you purchased insurance (property, health, life, and/or hazard type)?
  • Have you made the necessary financial arrangements in case of a sudden evacuation and power outage that shuts down local ATMs and banks?
  • have you organized important documents and records and stored them in a portable lock box or safe-deposit box?
  • Have you performed a home inventory video taping the contents stored them in a portable lock box or safe-deposit box?
  • Does your family have an established Emergency Communication Plan and evacuation plan in place and asked an out-of-state person to serve as the “family contact”?
  • Have you assembled a shelter-in-place Emergency Supplies Kit in case you have to shelter at home and you are without power?
  • Have you assembled a mobile Emergency Supplies Kit that can serve as a “grab and go” bag?
  • Are you or someone in your family trained in first aid and CPR?
  • Have you made they necessary preparations and arrangements for pets, seniors, and the disabled?
  • Have you familiarized yourself with the emergency plans of your family member’s employment building, school, day care center, or nursing home?

Hazard Specific Questions:

  • Is your home located in a flood plain?
  • Even if not in a flood plain, is your home downstream from a dam, levee or other impoundment?
  • Is there a high-hazard dam or significant-hazard potential dam as designated by the National Inventory of Dams (NID) or the Association of State Dam Safety Officials (ASDSO) near your home?
  • Is your home more than one story?
  • Is your home a wood frame construction?
  • Is your furnace, water heater, and electric panel elevated?
  • Do you have “check valves” been installed in sewer traps to prevent flood water from backing up into the drains of your home?
  • Have levees, beams or floodwalls been constructed to divert or stop flood waters?
  • Have basement walls been sealed with waterproofing compounds to avoid seepage?
  • Do you have Federal flood insurance? (Home owner’s insurance does NOT cover floods)

USGS Real-time Streamflow Map

The USGS WaterWatch – Real-time streamflow map tracks short-term changes (over several hours) in rivers and streams. The map depicts streamflow conditions as computed at USGS stream gages. The colors represent real-time streamflow compared to percentiles of historical daily streamflow for the day of the year.[3]

USGS Daily Streamflow Conditions [4]

Flood Insurance

Just a few inches of water from a flood can cause tens of thousands of dollars in damage. From 2008 to 2012, the average residential flood claim amounted to more than $30,000. Flood insurance is the best way to protect yourself from devastating financial loss.

Flood insurance is available to homeowners, renters, condo owners/renters, and commercial owners/renters.[5] Costs vary depending on how much insurance is purchased, what it covers and the property’s flood risk.

All policy forms provide coverage for buildings and contents. However, you might want to discuss insuring personal property with your agent, since contents coverage is optional. Typically, there’s a 30-day waiting period from date of purchase before your policy goes into effect. That means now is the best time to buy flood insurance.

Find a Flood Insurance Agent
Flood insurance can only be purchased through an insurance agent; you cannot buy it directly from the federal government. If your local insurance agent is unfamiliar with the NFIP you can:

  • Find an agent serving your area; or
  • Contact the The National Flood Insurance Program (NFIP) at (888) 379-9531 to request an agent referral.



  1. The National Flood Insurance Program – FloodSmart.gov – Website: http://www.floodsmart.gov/
    FEMA – Flood Map Service Center – Website: https://msc.fema.gov/webapp/wcs/stores/servlet/mapstore/homepage/MapSearch.html
  2. FloodSmart.gov – Defining Flood Risks: http://www.floodsmart.gov/floodsmart/pages/flooding_flood_risks/defining_flood_risks.jsp
  3. USGS Real-time Streamflow Map – Website: http://waterwatch.usgs.gov/index.php?id=real&sid=w__map
  4. Image Source: http://waterwatch.usgs.gov/index.php?id=real&sid=w__map [Accessed September 16, 2013]
  5. FloodSmart.gov – Residential Coverage: http://www.floodsmart.gov/floodsmart/pages/residential_coverage/rc_overview.jsp
  6. Image Source: http://www.floodsmart.gov/floodsmart/pages/residential_coverage/rc_overview.jsp [Accessed July 12, 2013]
  7. Image Source: http://www.floodsmart.gov/floodsmart/pages/flooding_flood_risks/defining_flood_risks.jsp [Accessed July 12, 2013]