What is a flood map and why does it change?
The Federal Emergency Management Agency (FEMA) works
with community leaders across the country to identify flood
hazards and promote ways to reduce the impact of those
and other hazards. Flood maps are used for floodplain
management, flood insurance rating, and flood insurance
requirements. Flood maps generally show a community’s
flood zones, regulatory requirements for the elevation or
flood-proofing of structures, and floodplain boundaries;
together they show the risk of flooding. High-risk zones,
known as Special Flood Hazard Areas or SFHAs, show where
floodwaters will be in a flood that has a one percent chance
of happening in any given year. Moderate- to low-risk zones
are where the risk of that level of flooding is less than one
percent per year. No matter where you live or work, some risk
of flooding exists.
Flood hazards change over time. How water flows and drains
can change by new land use and community development or
by natural forces such as changing weather, terrain changes,
or wildfires. To better reflect the current flood risk conditions,
FEMA uses the latest technology to update and issue new
flood maps nationwide to aid communities, property owners,
and other stakeholders in taking steps to address flood risks.
How are flood maps used?
Community officials use flood maps to help them understand
and communicate the local flood risk, manage their
floodplains, and require new and substantially-improved
buildings to be built more safely and mitigate losses from
future floods. These efforts make a safer community in which
to live and work.
Mortgage lenders use them to help determine a property’s
flood risk and decide whether to require flood insurance as a
requirement for a loan.
Insurance professionals use the maps to determine a
property’s flood risk and insurance cost.
Developers and builders use them as part of their location
siting and construction decisions.
Residents and business owners use flood maps to learn
about flood risk as they purchase property and investigate
how best, financially and tangibly, to protect their property
How do flood maps show flood risk?
Flood maps show the different flood zones. Moderate-to
low-risk areas are labeled Zone X (or Zones B and C on older
maps). High-risk areas begin with the letters A or V. Areas
where the risk is not known are shown with the letter D.
Base Flood Elevations (BFEs) displayed on flood maps show
the lowest height that floodwaters can be expected to reach
during a major flood and that participating NFIP communities
must consider in making floodplain management decisions.
How is the risk shown on the flood maps
reflected in insurance premiums?
If your building is in a high-risk area, you are likely to pay a
higher flood insurance premium than someone in a moderate- to
low-risk area. The exact amount you pay is based on several
things, including the flood zone and elevation of the building.
In a high-risk area, your insurance premium may also depend
on when your building was built compared to the date of the
community’s first flood map. Some buildings built before the
community’s first flood map, called pre-flood map, are eligible
for discounted rates.
How can I reduce my rates?
If you find you will have to pay a higher premium for flood
insurance, you can take these steps to help reduce the cost:
• Mitigate. Lowering your property’s exposure to flooding
may make you eligible for lower premium rates. For
example, you can fill in a basement or install flood
vents in the crawlspace beneath the lowest level of
your building; these actions help reduce the chance
that your building’s foundation will be damaged during
a flood and may lower your insurance premium. When
remodeling or rebuilding, you can consider elevating your
entire structure. Also, something as simple as raising
heating and cooling systems, water heaters, the electrical
panel, and other mechanical items so that they are less
likely to be damaged or destroyed in a flood may offer
some premium savings.
• Encourage community action. You can encourage your
community to participate in the Community Rating Service
(CRS), if it doesn’t already. CRS is a voluntary incentive
program that recognizes communities for implementing
floodplain management practices that exceed the National
Flood Insurance Program (NFIP) minimum requirements.
In exchange for a community’s proactive efforts to
reduce flood risk, policyholders can receive reduced flood
What is a flood map and why does it change?