U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Weather Service

August 2002

The Great Flood of 1993 Top Photo: Scott Dines, St. Louis Post-Dispatch. Bottom Photo: Jim Rackwitz, St.Louis Post-Dispatch
Why Should I be Concerned

About Flooding?

This preparedness guide explains flood-related

hazards and suggests life-saving actions you can take.

With this information you can recognize a flood

potential, develop a plan, and be ready when

threatening weather approaches. Remember...your

safety is up to YOU!

In the long term, floods kill more people in the United

States than other types of severe weather. In recent

years, only heat surpassed flood fatalities. Floods can

roll boulders the size of cars, tear out trees, destroy

buildings and bridges, and pose a significant threat to

human lives.

Online Resources

Additional flash flood/flood-related safety information

can be obtained at:

American Red Cross: 

http://www.redcross.org/

U.S. Geological Survey:

http://www.usgs.gov/

Federal Emergency Management Agency:

http://www.fema.gov/

National Weather Service:

http://www.nws.noaa.gov/

2

Floods The Awesome Power

”Flooding never happens here. Tom

was trying to get home. He drives on

the road near the stream every day.

We knew it had been raining a lot, but

it had been so dry, we were actually

happy about the rain. Tom saw some

water on the road, but thought it

wasn't that deep. And, after all, he

was in his truck, high up off the

ground. But then his truck started to

float, and before he knew it, his truck

was washed downstream with him in

it. Fortunately, his truck got stuck on

a rock or something, and someone

saw him and threw him a line. Tom

got out okay. But we really learned

from this, not to drive in floods.”

- Testimony of Marilyn and Tom

(last name requested to be withheld),

interviewed by the American Red

Cross after Tropical Storm Allison

struck Texas in June 2001

River Flooding

Photo: Jim Reed, Digital Vision, New York, NY
3

What are Flash Floods?

A flash flood is a rapid rise of water along a stream or

low-lying urban area. Flash flood damage and most

fatalities tend to occur in areas immediately adjacent to

a stream or arroyo, due to a combination of heavy rain,

dam break, levee failure, rapid snowmelt, and ice jams.

Additionally, heavy rain falling on steep terrain can

weaken soil and cause mud slides, damaging homes,

roads, and property.

Flash floods can be produced when slow moving or

multiple thunderstorms occur over the same area.

When storms move faster, flash flooding is less likely

since the rain is distributed over a broader area.

Flash Flood Risk in Your Car, Truck,

or Sport Utility Vehicle (SUV)

Almost half of all flash flood fatalities occur in

vehicles. Contrary to popular belief, many people

don’t realize two feet of water on a bridge or highway

can float most vehicles. If the water is moving rapidly,

the car, truck, or SUV can be swept off the bridge and

into the creek. 

Water can erode the road bed creating unsafe driving

conditions. Underpasses can fill rapidly with water,

while the adjacent roadway remains clear. Driving

into a flooded underpass can quickly put you in

5-6 feet of water. Many flash floods occur at night

when flooded roads are difficult to see. 

When you approach a flooded road, TURN AROUND

AND GO ANOTHER WAY!

Barricades are put up for your

protection. Turn around

and go another way!

Source: National Weather Service
Flash Flood Risks at Home, Work,

or School

Since many flash floods occur along small streams,

you can determine your risk by knowing your

proximity to streams. Flooding can be caused by rain

falling several miles upstream and then moving

downstream rapidly. 

Densely populated areas have a high risk for flash

floods. The construction of buildings, highways,

driveways, and parking lots increases runoff by

reducing the amount of rain absorbed by the ground.

This runoff increases the flash flood potential.

Sometimes, streams through cities and towns are

routed underground into storm drains. During periods

of heavy rainfall, storm drains may become

overwhelmed and flood roads and buildings. Low

spots, such as underpasses, underground parking

garages, and basements can become death traps.

Embankments, known as levees, are built along rivers

and are used to prevent high water from flooding 

bordering land. In 1993, many levees failed along the

Mississippi River, resulting in devastating flash floods. 

Dam failures have played a deadly role in the

history of flash flooding. The United States has about 

76,000 dams, and about 80 percent of those are 

earthfill construction. Be aware of any dams upstream

of your location. Earthen dams are more easily

compromised by heavy rainfall than are concrete

structures. Water flowing over an earthen dam can

cause the dam to weaken or fail, sending a destructive

wall of water downstream.

Flash Flood Risk to Recreation

(Camping, Hiking, Boating, Fishing)

Many people enjoy hiking, fishing, or camping along

streams and rivers. Listen to weather forecasts and

keep away from streams if thunderstorms have 

happened or have been predicted upstream from where

you are. A creek only 6 inches deep in mountainous

areas can swell to a 10-foot deep raging river in less

than an hour if a thunderstorm inundates the area with

intense rainfall.

When thunderstorms are in the area, stay alert for

rapidly changing conditions. You may notice the

stream start to rise quickly and become muddy. You

may hear a roaring sound upstream that may be a flood

wave moving rapidly toward you. Head immediately

for higher ground. Don't be swept away by the rising

water. There are dangers associated with

fast-moving water, but with common sense

and some preparation, outdoor enthusiasts

can enjoy a safe day along a stream or river.

Source: National Weather Service 4

Floods The Awesome Power
Where You Are Determines Your

Flash Flood/Flood Risk

Mountains and steep hills produce rapid runoff

and quick stream response. Rocks and clay soils

do not allow much water to infiltrate the ground.

Steep narrow valleys generate rapid flowing

waters that can rise quickly to a considerable

depth. Saturated soil also can lead rapidly to

flash flooding.

Very intense rainfall can produce flooding even

on dry soil. In the West, most canyons and

"small streams" are not easily recognizable as a

source of danger. Canyons can be scoured with

sudden walls of water 10-15 feet high (e.g.,

Antelope Canyon, Arizona, August 1997,

11 fatalities). 

Additionally, high risk locations include low

water crossings, recent burn areas in mountains,

and urban areas from pavement and roofs which

concentrate rainfall runoff.

5

Listen for a roaring sound

upstream as flood waters

could be headed your way! 

Look for rapidly rising water

and/or water turning muddy!

Remember to climb to

safety if your hear or see

signs of a flood!

Road damage as a result of flash flooding

Photo: Steve Allen Photography, Waitsfield, VT
What are River Floods?

A flood is the inundation of a normally dry area caused

by an increased water level in an established

watercourse. River flooding is often caused by:

✓Excessive rain from tropical systems

making landfall.

✓Persistent thunderstorms over the same

graphical area for extended periods

of time.

✓Combined rainfall and snowmelt.

✓Ice Jam.

6

Floods The Awesome Power

River flooding due to excessive rain

River flooding due to ice jam

River flooding due to combined rainfall and snowmelt

Persistent thunderstorms

over the same graphical area

can lead to river flooding

Photo: Steve Allen Photography, Waitsfield, VT

Photo: Steve Allen Photography, Waitsfield, VT

Photo: Jim Rackwitz, St. Louis Post-Dispatch
Tropical Cyclones and

Their Remnants

Floods are often produced by hurricanes, tropical

storms, and tropical depressions. A tropical cyclone's

worst impact may be the inland flooding associated

with torrential rains.

When these storms move inland, they are typically

accompanied by very heavy rain. If the decaying

storms move slowly over land, they can produce

rainfall amounts of 20 to 40 inches over several days.

Widespread flash flooding and river flooding can result

from these slow-moving storms. 

A hurricane also can produce a deadly storm surge that

inundates coastal areas as it makes landfall. Storm

surge is water pushed on shore by the force of the

winds swirling around the storm. This advancing

surge combines with the normal tides to create the

hurricane storm tide, which can increase the average

water level 15 feet or more.

The greatest natural disaster in the United States, in

terms of loss of life, was caused by a storm surge and 

associated coastal flooding from the great Galveston,

Texas, hurricane of 1900. At least

8,000 people lost their lives. 

Deaths from hurricane coastal flooding have fallen

dramatically in recent years, but storm surge remains

a great threat.

Coastal Flooding

Floods are long term events

and may last days, weeks,

or LONGER!

Source: National Weather Service 7
Stay Informed

Listen to National Oceanic and Atmospheric and

Administration (NOAA) Weather Radio,

commercial radio, television, or go to the Internet for

the latest flash flood and flood WATCHES,

WARNINGS, and WEATHER ADVISORIES at:

http://iwin.nws.noaa.gov/iwin/nationalwarnings.html

For planning purposes, Flood Hazard Map

information is only a click away by going to the

Federal Emergency Management Agency Web page at:

http://www.fema.gov/mit/tsd

The Advanced Hydrologic

Prediction Service (AHPS)

AHPS of the National Weather Service provides

improved river and flood forecasting and water

information. AHPS has a suite of new graphical

internet products to assist community leaders and

emergency managers in making better life and

cost-savings decisions about evacuating people and

moving property before a flood occurs.

AHPS major themes:

✓Short term through long-term forecasts

(from minutes to months including probabilistic

products for risk management decisions).

✓Real-time flood forecast maps depicting areal

extent of flooding.

✓More timely and accurate flash flood warnings

through the use of enhanced flash flood decision

assistance tools.

Accordng to the National Hydrologic Warning Council

report, “Use and Benefits of the National Weather

Service River and Flood Forecasts,” AHPS, once fully

implemented throughout the United States, will

provide more than $750 million in economic benefits

each year.

Additional AHPS information can be obtained at:

http://www.nws.noaa.gov/om/water/Ahps.shtml

Floods The Awesome Power

8

AHPS Weather Display

Source: National Weather Service
9

Use NOAA Weather Radio!

NOAA Weather Radio is the best way to receive

warnings from the National Weather Service. NOAA

Weather Radio is a nationwide network of radio

stations broadcasting continuous weather

information direct from a nearby National

Weather Service office. 

NOAA Weather Radio

broadcasts National Weather

Service warnings, watches,

forecasts, and other hazard

information 24-hours a

day. The average

reception range is a

40-mile radius from the

transmitter, depending on

topography. Be aware of the potential for flooding

before the heavy rainfall begins by listening to NOAA

Weather Radio.

Purchase a NOAA Weather Radio that has a battery

back-up, a Specific Area Message Encoder (SAME)

feature, which automatically alerts you when a Watch

or Warning is issued for your county or parish, and one

that can receive all seven NOAA Weather Radio

frequencies.

NOAA Weather Radio can also broadcast post-event

information for all types of hazards - both natural

(earthquakes, hurricanes and volcanos) and

environmental (chemical or oil spills). Known as the 

"Voice of the National Weather Service," NOAA

Weather Radio is provided as a public service by the

Department of Commerce's NOAA.

The NOAA Weather Radio network has more than

650 transmitters, covering the 50 states, adjacent

coastal waters, Puerto Rico, the U.S. Virgin Islands,

and the U.S. Pacific Territories. NOAA Weather Radio

requires a special radio receiver or scanner capable of

receiving the signal. Broadcasts are found in the

public service band at these seven frequencies (MHz):

162.400, 162.425, 162.450, 162.475, 162.500,

162.525, 162.550 (also known as channels 1

through 7).

NOAA Weather Radio requires a special radio receiver

or scanner capable of picking up the signal. These

receivers can be purchased at retail electronic and

sporting good stores.

NOAA Weather Radio Bands:

Channel Frequencies (MHz)

 1 162.550

 2 162.400

 3 162.475

 4 162.425

 5 162.450

 6 162.500 

 7 162.525

The NOAA Weather Radio Exhibit
Community Preparedness Plans

After you have developed a personal/family safety

plan, find out about your community safety plan. Each

community prone to a flash flood/flood should develop

a safety plan. Local officials should have detailed

information for your immediate area. Please listen and

follow their recommendations before, during, and after

a storm.

The best way to prevent loss of life is to design and

build communities where roads remain usable and

undamaged during floods, and where homes and

businesses are protected. While this may not always

be possible, it is a goal we hope every community

strives to reach.

Protect yourself, your home, your family, and your

financial future.

National Flood Insurance Program 

One of the most important things you can do to protect

your home and family before a flood is to purchase a

flood insurance policy. You can obtain one through

your insurance company or agent. Your agent can tell

you whether the standard or preferred policy (for

medium or low risk) is most appropriate for you.

Flood insurance is backed by the National Flood

Insurance Program (NFIP), administered by the

Federal Emergency Management Agency. Your

homeowners insurance does not cover flood damage.

Everyone has some flood risk and anyone in a

participating community is eligible. Don't wait until a

flood is coming to purchase your policy. It normally

takes 30 days after purchase for a flood insurance

policy to go into effect. For more information about

the NFIP and flood insurance, contact your insurance

company or call the NFIP at 1-800-427-4661. 

Check with your city or county government (start with

the Building or Planning Office) to find out if you live

in a participating community and what flood risk

information is available where you live.

10

Floods The Awesome Power

To help America prepare for the ravages

of flash floods and floods, the

National Weather Service has designed

StormReady, to arm America's

communities with the communication

and safety skills necessary to save

lives and property. 

More information is available at:

http://www.nws.noaa.gov/stormready

✓Provide river and rainfall readings to

emergency managers and the

National Weather Service.

✓Establish early warning procedures.

✓Create and operate a Local Flood Warning

System to identify areas vulnerable

to flooding.

✓Produce and follow the flood emergency

action plans:

Contact your local emergency

management agency or local National

Weather Service office for further

information on Local Flood Warning

Systems, or visit:

What My Community Can Do

http://www.nws.noaa.gov/oh/docs/alfws-handbook

Photo: Kevin Manning, St. Louis Post-Dispatch
11

Streamgage Data Save Lives

National Weather Service forecasters rely on a network

of almost 10,000 streamgages to monitor the height of

rivers and streams across the Nation. This information

provides present river conditions and is the initial

information needed to develop a river forecast. Most

of the streamgages are maintained by the U.S.

Geological Survey, the U.S. Army Corps of Engineers,

and the Department of Agriculture. Some streamgages

are read manually by dedicated volunteer observers. If

you would like to volunteer as a cooperative observer

visit the web site at: 

http://www.nws.noaa.gov/om/coop/become.htm

Many communities nationwide have partnered with the

National Weather Service and other federal agencies

(e.g., U.S. Geological Survey and the U.S. Army Corps 

of Engineers) to implement dense networks of

precipitation gages and streamgages to monitor and

detect flooding in their community. These networks

are often referred to as Local Flood Warning Systems.

National Weather Service

forecasters rely on a network of

almost 10,000 streamgages to

monitor the height of rivers and

streams across the Nation

Source: National Weather Service
What You Can Do Before

the Flood...

When you receive a Flood Watch:

✓A Watch is issued when flooding is

possible within the watch area. When a

flood watch is issued, you should be

aware of potential flood hazards.

Everyone in a Watch area should be

ready to respond and act quickly. 

✓Have an evacuation plan in place

BEFORE flooding occurs. Flooded

roads may cut off your escape route.

Head for higher ground before the water

becomes too deep. Remember - just six

inches of rapidly flowing water can knock

you off your feet. For information on

how or what to do if you are advised to

evacuate, visit the American Red Cross

Web page at:

http://www.redcross.org/services/disaster/

beprepared/evacuation.html

✓Know your flood risk and the elevation

above which flooding occurs. Do

streams or rivers near you flood easily?

If so, be prepared to move to a safe

place. Know your evacuation routes. 

✓Find out if you are located in a high,

medium, or low flood risk area. Check

with your city or county government to

find out if your community is participating

in the National Flood Insurance Program.

Start with the Building or Planning

Department to review the Flood

Insurance Rate Maps, published by the

Federal Emergency Management

Agency.

✓Develop an evacuation plan. Everyone

in your family should know where to go if

they have to leave. 

12

Floods The Awesome Power

Major Flooding from Tropical Storm Allison in Houston, Texas, June 2001

Photo: Harris County Flood Control District, Houston, Texas
13

✓Discuss flood plans with your family.

Everyone should know what to do in

case all family members are not

together. Discussing flood plans ahead

of time helps reduce fear and anxiety

and lets everyone know how to respond.

✓Determine if the roads you normally

travel to reach your home or job will be

flooded during a storm. If so, look for

alternative routes to use during flooding.

✓Keep a NOAA Weather Radio, a

battery-powered portable radio,

emergency cooking equipment, and

flashlights in working order.

✓Have a professional install check-valves

in plumbing to prevent flood waters from

backing up into the drains of your home.

✓Keep your automobile fueled; if electric

power is cut off, gas stations may not be

able to operate pumps for days.

✓Store drinking water in food-grade

containers. Water service may

be interrupted.

✓Keep a stock of food requiring little

cooking and no refrigeration; electric

power may be interrupted.

✓Keep first-aid supplies and prescription

medicines on hand.

Fact

The 100-year flood is a

climatic average; there

is a 1% chance that a

100-year flood will

occur in any given year

Fact

Flash floods occur in

all 50 states, including

Alaska and Hawaii.

Fact

Flash floods can occur

in dry arroyos and

urban areas where no

streams are present.

Fact

Many flash floods

occur at night.

Fact

Unfortunately, many

homeowners do not

find out until it is too

late that their policies

do not cover flooding. 

Contact your

insurance company or

agent to buy

flood insurance.

Fact

You are still eligible to

purchase flood

insurance after your

home, apartment, or

business has been

flooded, provided your

community is

participating in the

National Flood

Insurance Program.

Fact

Two feet of rushing

water can carry away

most vehicles

including SUVs

and pickups.

Myth

A 100-year flood

occurs only once

every 100 years.

Myth

Flash floods mainly

occur in the eastern

United States.

Myth

Flash floods occur

only along

flowing streams.

Myth

Flash floods occur

mainly in the late

afternoon and evening.

Myth

Homeowners

insurance policies

cover flooding.

Myth

You can't

buy flood insurance

if your property

has been flooded.

Myth

Larger vehicles, such

as SUVs and pickups

are safe to drive

through flood waters.
What You Can Do During

the Flood...

When you receive a Flood Warning:

✓If advised to evacuate, do so

immediately! Families should use only

one vehicle to avoid getting separated

and reduce traffic jams. Move to a safe

area before access is cut off by flood

water. Continue listening to NOAA

Weather Radio, radio, or television for

information concerning the flooding.

✓Don't drive if you don't have to.

✓Get out of areas subject to flooding.

This includes dips, low spots, canyons,

washes, etc. Do not attempt to cross

flowing streams.

✓Never try to walk, swim, drive, or play in

flood water. You may not be able to see

how fast the flood water is moving or see

holes or submerged debris.

✓Do not camp or park your vehicle along

streams and washes, particularly during

threatening conditions.

✓Be especially cautious at night when it is

harder to recognize flood dangers.

✓Do not attempt to drive through a

flooded road. The depth of water is not

always obvious. The road bed may be

washed out under the water, and you

could be stranded or trapped. 

✓Do not drive around a barricade.

Barricades are there for your protection.

Turn around and go another way!

✓If the vehicle stalls, leave it immediately

and move to higher ground. Rapidly

rising water may engulf the vehicle and

its occupants sweeping them away.

Vehicles can be swept away by as little

as 2 feet of water.

✓Children should NEVER play around

high water, storm drains, viaducts, or

arroyos. It is very easy to be swept

away by fast-moving water.

✓If you come upon a flowing stream

where water is above your ankles,

STOP! Turn around and go another way.

Climb to higher ground. If it is moving

swiftly, even water 6 inches deep can

knock you off your feet. Many people

are swept away wading through flood

waters, resulting in injury or death.

14 

Floods The Awesome Power

During a Flood Warning,

Don’t Drive

Whenever Possible!
15

What You Can Do After

the Flood...

✓Get necessary medical care at the

nearest hospital. The American Red

Cross can provide shelter, food, and first

aid, as well as a means to purchase new

clothing.

✓Do not visit disaster areas. Your

presence might hamper rescue and

other emergency operations.

✓If the power is out, use flashlights, not

candles.

✓Use flashlights, not lanterns, torches, or

matches, to examine buildings.

Flammables may be inside.

✓Report broken utility lines to appropriate

authorities.

✓Boil drinking water before using. Wells

should be pumped out and the water

tested for purity before drinking. If in

doubt, call your local public health

authority.

✓If fresh or canned food has come in

contact with flood waters, throw it out.

✓Take steps to reduce your risk of future

floods. Make sure to follow local building

codes and ordinances when rebuilding,

and use flood-resistant materials and

techniques to protect yourself and your

property from future flood damage. 

Do not visit disaster areas

following a flood. Your presence

may hamper urgent emergency

response and rescue operations!

Photo: Federal Emergency Management Agency
Gather information about hazards. Contact your local

National Weather Service office, emergency

management office, and American Red Cross chapter.

Find out what types of disasters could occur and what

you should do. Learn about your community's methods

of warning people and evacuation plans. Ask your

insurance agent about flood insurance. Find out what

you can do to protect your home from the effects of

natural hazards that could occur where you live. Meet

with your family to create a plan. Discuss the information

you have gathered. Pick two places to meet: a spot

outside your home for an emergency such as a fire, and

a place away from your neighborhood in case you can't

return home. Choose an out-of-town family member or

friend as your family check-in contact for everyone to

call if the family gets separated, and a backup out-ofneighborhood friend in case the first one does not

answer. Discuss what you would do and how to do it if

advised to evacuate. Use one vehicle only to avoid

getting separated and reduce traffic jams. Decide what

measures you will take to make your home

less vulnerable to disasters.

Floods The Awesome Power

Do You Have a Family Disaster Plan?

I. Gather Information About Hazards

II. Implement Your Plan

1. Post emergency telephone numbers by phones and in

address lists each person carries with them. Include cell

phone numbers of family and contact-points.

2. Install safety features in your home, such as smoke

alarms and fire extinguishers. 

3. Inspect your home for potential hazards such as items

that can move, fall, break, or catch fire, and correct

them. 

4. Make physical changes that will make your home less

vulnerable; install check-valves and hurricane shutters;

strap the hot water heater to wall studs.

5. Have your family learn basic safety skills such as

CPR/Automated External Defibrillator (AED) and first aid;

how to use a fire extinguisher; and how and when to turn

off water, gas, and electricity at the main switches and

valves. Know how to operate a NOAA Weather Radio.

6. Teach children how and when to call 9-1-1 or your

local Emergency Medical Services number.

7. Keep emergency supplies in your home sufficient for

3 days to a week, if your area has ever lost basic water,

electricity and gas service for a week or longer.

Assemble a disaster supplies kit with things you will

need if you have to evacuate. Store these supplies in

sturdy, easy-to-carry containers such as backpacks or

duffel bags.

8. Keep important family documents in a waterproof and

fire-resistant container.

9. Keep a smaller emergency kit with seasonal supplies,

tools, and clothes in the trunk of your car.

10. Each person who has a cell phone should carry it

and keep it turned on to receive calls in any emergency

situation.

III. Prepare a Disaster Supplies Kit to Include:

• At least a 3-day water supply (one gallon per person

per day) • Food that won't spoil • One change of

clothing and footwear per person • One blanket or

sleeping bag per person • First-aid kit • Prescription

medicines • Emergency tools • Battery-powered

NOAA Weather Radio • Portable radio • Flashlight with

extra batteries • Extra set of car keys • Cash and credit

card • Special items for infant, elderly, and disabled family members.

Ask questions to make sure each family member

remembers meeting places, telephone and cell phone

numbers, and safety rules. Conduct drills. Test smoke

alarms monthly and change the batteries at least once a

year. Test and recharge fire extinguishers according to

manufacturer's instructions and make sure family 

members remember how to operate them. Replace

emergency food and water supplies once every six

months. Contact your local National Weather Service

office, American Red Cross chapter or emergency

management office for a copy of Your Family Disaster

Plan (FEMA L-191 or ARC4466).

IV. Practice and Maintain Your Plan

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