MAPPING

FLOOD RISKS

An Overview to Floodplain 

Management & Flood Insurance

FEMA L-257 / April 2014

During a 30-year mortgage, property owners 

located in high-risk flood zones have a 

26% chance of experiencing flood damage, 

compared to a 9% chance* of experiencing a 

structural fire.

Homeowners insurance does not cover flood damage.

* Probability based on yearly reported structural fire data from the 

National Fire Protection Association.

HOW CAN I REVIEW A FLOOD MAP THAT IS 

BEING UPDATED? 

After an engineering study has been completed, FEMA will 

provide preliminary versions of the updated map panels and the 

accompanying Flood Insurance Study report to community officials 

for review and comment and hold public meetings to present the 

results of the engineering studies. If new or modified base flood 

elevations or base flood depths are proposed, FEMA will initiate a 

statutorily required 90-day appeal period.

The 90-day appeal period begins on the date of the second 

publication of proposed base flood elevations in the local newspaper. 

During the appeal period, any owner or renter of real property 

affected by the proposed elevations within the community may 

file a written appeal based on a demonstration that the elevations 

proposed by FEMA are scientifically or technically incorrect. 

To determine whether a map update is in progress in your 

community or to view the preliminary version of the map and 

report, please contact your local floodplain administrator or visit 

your Community Map Repository. For assistance in locating 

the Community Map Repository, please call the FEMA Map 

Information eXchange (FMIX) at the number shown below. 

After community and public reviews have been completed and 

appeals have been addressed, FEMA publishes final versions of 

the map and report. Once published the community has 6 months 

to legally adopt the final map. The new map and report are available 

for review through the FEMA Flood Map Service Center at 

http://msc.fema.gov.

FOR MORE INFORMATION 

• For more information on the NFIP, please read “Answers to 

Questions About the NFIP,” found on the FEMA website at www.

fema.gov/media-library/assets/documents/272?id=1404 or may be 

ordered by calling 1-800-480-2520.

• For more information on flood insurance, including information 

on the Preferred Risk Policy, please visit www.floodsmart.gov

or the “NFIP Publications” page at www.fema.gov/nationalflood-insurance-program/national-flood-insurance-programpublications.

• For more information on flood hazard mapping products and 

processes, including tutorials on map change request procedures, 

please visit the “Flood Hazard Mapping” page at www.fema.gov/

national-flood-insurance-program-flood-hazard-mapping.

• For more information on floodplain management, please visit 

the “Floodplain Management” page on the FEMA website at 

www.fema.gov/national-flood-insurance-program.

• There are many resources in the FEMA Resource & Document 

management system at: www.fema.gov/resource-document-library.

UNDERSTANDING FLOODING

When flooding occurs, one question is always in the forefront: why did 

it flood? Unfortunately, there is not one simple answer. Four different 

types of floodplains (valley, major river, shallow, coastal), each with its 

own characteristics, are illustrated in the first four diagrams below. The 

ponding diagram below shows the type of flooding caused by intense 

rainfall where no identifiable floodplain exists.

Some factors that aggravate flooding include:

• Changes to developed and 

undeveloped land

• Changes to rivers or streams

• Erosion

• Poor channel maintenance

Through wise floodplain management, communities can protect 

their citizens against much of the devastating financial loss 

and emotional toll caused by flood disasters. Residents and 

business owners are encouraged to purchase and maintain 

flood insurance policies and to consider flood-proofing or taking 

other protective measures to address flood risks to their own 

properties.

TYPES OF FLOODING

The ground in this type of area is more 

“defined,” with creek valleys. Flooding 

can be very deep and usually extends 

for a few days.

The floodplain along major rivers can 

be large, deep, and swift, and flooding 

conditions may last a week or more.

Shallow floodplains affect thousands of 

residences and businesses. When the 

channel capacity is exceeded, flooding 

begins. This flooding usually lasts 

hours, rather than days.

Coastal flooding occurs when storm 

events coincide with tides, tsunamis, 

or a hurricane surge flood. High water 

levels are usually accompanied by 

waves capable of causing significant 

structural damage. 

This type of flooding is not restricted 

to any one area of the U.S. or to any 

one area of a community. It can occur 

almost ANYWHERE. When intense 

local rainfall exceeds storm sewer or 

roadside ditch capacity, the water can 

“pond” in the streets deep enough to flood residences that are 

not even near a creek or bayou. The water will seek a path to the 

channel by flowing overland (sheet flow). 

Levees are designed to protect against 

a certain level of flooding. However, 

levees can also be overtopped, or 

even fail during large floods. No levee 

provides full protection from flooding 

- even the best structure cannot 

completely eliminate all flood hazards. 

www.FloodSmart.gov

An official site of the 

National Flood Insurance Program

If you would like a FEMA Map 

Specialist to assist you with 

requesting a change to the Flood 

Insurance Rate Map for your 

community, please call the FMIX 

toll free, at 1-877-FEMA MAP 

(1-877-336-2627).

FEMA L-257 / Catalog No. 09044-1 www.fema.gov
WHY MAP FLOODPLAINS?

Mapping floodplains is vital 

for implementing all floodplain 

management strategies. It 

creates broad-based awareness 

of flood risk; provides the 

data necessary for floodplain 

management and land-use 

regulations, hazard mitigation 

programs, and rating flood 

insurance for new construction on an actuarial basis; and supports 

the decision making process with respect to the natural values of 

floodplains.

WHAT IS THE NATIONAL FLOOD INSURANCE 

PROGRAM?

Congress created the National Flood Insurance Program (NFIP) 

in 1968 as an alternative to taxpayer-funded disaster relief for 

flood survivors. The NFIP enables property owners and renters 

in participating communities to purchase flood insurance as a 

financial protection against flood losses. In exchange, States and 

communities adopt floodplain management regulations designed to 

reduce flood risks and future flood damage.

FREQUENTLY ASKED QUESTIONS

Who can purchase flood insurance? 

NFIP flood insurance is available to homeowners, business owners, 

condominium owners and associations, as well as tenants of eligible 

buildings located in NFIP participating communities.

Where can I purchase flood insurance? 

Any licensed casualty insurance agent in your State can sell you an 

NFIP policy. Call 1-888-225-5356 for more information.

Why should I purchase flood insurance? 

Homeowners or rental insurance does not cover flood damages and 

floods may occur even in areas designated as moderate or minimal 

risk. Approximately 25 percent of all flood insurance claims occur in 

these areas. The Federal Emergency Management Agency (FEMA) 

encourages you to maintain flood insurance coverage, even if you 

are not required to do so by the lender. You may be eligible to pay 

much less for flood insurance coverage if the property is located in an 

area designated as moderate or minimal risk. For more information, 

including pricing options, contact your insurance agent.

LEVEE FLOOD RISK 

There are currently thousands of miles of levees across the country 

providing some level of protection for millions of people, so it 

is important for individuals to understand the risks associated 

with living behind levees. No levee provides full protection from 

flooding - even the best structure cannot completely eliminate all 

flood risks. But there are constant efforts being made by a variety 

of organizations to reduce that risk and keep levees operating 

efficiently. For more information: www.floodsmart.gov/floodsmart/

pages/flooding_flood_risks/levees.jsp

WHAT ROLE DOES THE 

FLOOD INSURANCE RATE MAP 

PLAY IN THE FLOOD INSURANCE PROGRAM?

As the Federal agency responsible for administering the NFIP, 

FEMA identifies flood hazards, assesses flood risks, and provides 

appropriate flood hazard and risk information to communities 

nationwide. This information is provided to communities in the 

form of maps, known as Flood Insurance Rate Maps (FIRMs).

FIRMs are used an estimated 30 million times 

annually for:

• Enforcing State and community floodplain management 

regulations.

• Calculating flood insurance premiums.

• Determining whether property owners are required by law to 

obtain flood insurance as a condition of obtaining loans from 

federally-backed lending institutions or other federally-based 

financial assistance. 

FIRMs are also used by States and communities for emergency 

management, land-use and water resource planning, and by 

Federal agencies implementing Executive Order 11988 for 

Floodplain Management.

Most importantly, FIRMs are used for determining where flood 

insurance must be purchased and how much that insurance 

will cost based on the flood risk. Federally regulated or insured 

lenders are obligated to require flood insurance to secure loans for 

all structures located in high-risk areas, as shown on the FIRM. 

Through the NFIP, property owners and renters in participating 

communities are able to insure themselves against flood losses.

The NFIP is a public safety program implemented 

at the local level 

A FIRM can help property owners determine how high to 

elevate the home in order to be protected from the next flood 

event. FIRMs reflect the results of engineering studies, known 

as Flood Insurance Studies (FIS), which include examinations of 

historical flood records, topographic surveys, and other data. In 

many cases the FIS will establish base flood elevations. The base 

flood is the flood that has a 1-percent chance of occurrence in 

any given year. Along rivers, streams, and lakes, these elevations 

indicate the level at which flooding is expected to occur during 

the 1-percent-annual-chance flood event. Along the coast, these 

elevations are the result of the analysis of storm surge, wind 

direction and speed, wave heights, and other factors. FEMA 

is updating and modernizing existing FIRMs for most of the 

United States. The components of these modernized maps are 

shown below.

By employing wise floodplain management, NFIP communities 

can help protect citizens from future flood disasters. Managing 

development in floodplains results in construction practices that 

can reduce future flood losses and high costs associated with flood 

disasters thereby easing the emotional toll experienced by citizens 

when their personal property is damaged by flood waters.

Base Map Data

+

Topographical Data

+

Flood Data

=

Final Composed 

FIRM

How to obtain a flood map

Every property is at some risk of flooding, even those not located near a known flooding source such as a river, ocean, or lake. To find 

out more about your flood risk, visit www.floodsmart.gov. For a more detailed analysis of your risk, use FEMA’s National Flood Hazard 

Layer (NFHL) tool, which provides FEMA flood hazard data that can be “layered” over such software applications as Google EarthTM

. For 

instructions on using the NFHL in Google Earth visit www.fema.gov/media-library/assets/documents/13446?id=3289.

As a property owner or renter, you should learn the flood risk for your residence or building by reviewing the NFIP flood map for your 

community. Copies of the flood map are available to view in either draft (preliminary) or final (effective) form at the Community Map 

Repository, which is usually maintained by your local floodplain administrator at the planning and zoning office. You can view an effective 

digital flood map for your community on the FEMA Map Service Center (MSC) website: https://msc.fema.gov.

If further assistance is needed, the MSC or FEMA Map Information eXchange (FMIX) can be called toll free at 1-877-FEMA MAP 

(1-877-336-2627). Flood Insurance Study (FIS) reports, FIRM spatial databases, and related products can be downloaded from the MSC 

website. A section of a particular flood map known as a FIRMette can be created on the MSC website by selecting a desired area from the 

online image of a particular flood map. A FIRMette is free and available for many aspects of the NFIP including floodplain management, 

flood insurance, and the enforcement of mandatory flood insurance purchase requirements.

In addition to calling FMIX, you can e-mail FEMAMapSpecialist@riskmapcds.com or submitting a request in writing to the Federal 

Emergency Management Agency, Map Service Center, P.O. Box 3617, Oakton, Virginia 22124-9617.

HOW DO I CHANGE THE FLOOD MAP?

FEMA exercises great care to ensure that the analytical methods 

used for its engineering studies are scientifically and technically 

correct. FEMA also uses the best available technologies to ensure 

that the maps depict accurate flood risks.

Even so, FEMA recognizes that changes to flood maps might be 

necessary. Therefore, FEMA has established procedures for property 

owners who believe they have been incorrectly included in a highrisk area, known as a Special Flood Hazard Area (SFHA), on the 

flood insurance rate map (FIRM). 

Property owners interested in 

having FEMA examine the SFHA 

designation for their property 

can submit technical data and 

supporting documentation to 

FEMA in support of a map change, 

also known as a map amendment. 

If the documentation supports a map amendment, FEMA will 

issue a formal decision in the form of a Letter of Map Amendment 

(LOMA), removing the SFHA designation from the property. The 

LOMA can be used to work with a lender to remove the Federal 

mandatory flood insurance purchase requirement and to work 

with the flood insurance agent to bring down the premium cost. 

Lenders, however, may still opt to require flood insurance as a 

condition of any mortgage. Even if the SFHA designation has been 

removed from a property, flooding can still occur, so maintaining 

flood insurance is highly recommended. As a result of a LOMA, the 

property owner may be eligible for a lower-cost policy, referred to as 

a Preferred Risk Policy (PRP).

FEMA has a similar process for properties that have been elevated 

by the placement of earthen fill. The document issued by FEMA 

for these cases is called a Letter of Map Revision Based on Fill 

(LOMR-F).

In making amendments and revisions, FEMA adheres to the same 

engineering standards applied in the preparation of the effective 

FIRM and related products. 

FEMA has added new capabilities to its convenient web application 

tool, the Online LOMC, to easily request a Letter of Map 

Amendment. www.fema.gov/national-flood-insurance-programflood-hazard-mapping/change-flood-zone-designation-online-letter.

Additional information about map changes, including the current 

fee schedule for map change requests, is available by calling the 

FEMA Map Information eXchange (FMIX) toll free, at 1-877-

FEMA MAP (1-877-336-2627) or by visiting www.fema.gov/

forms-documents-and-software/flood-map-related-fees#2.

ONLINE

LOMC

Sample of Digital Flood Hazard Data