Flooding
Introduction
Floods kill people and destroy homes in many parts of the United States every year.
Federal agencies estimate that an average of over 125 people die every year in the
United States because of flooding, although losses vary widely from year to year.
Property damage ranges into the billions each year, and has been rising in recent
decades.
Of course the live video of a family clinging to their car in a swollen river as
rescuers winch down from a helicopter is so compelling that few viewers can change
channels. But flooding is also worth covering because if people are informed, they
can make decisions which will save lives and reduce property loss.
Background and Context
As the deadliest and most damaging of U.S. weather hazards, floods have long been
the focus of dreadful fascination by the public. Sometimes it is the scale that
awes us—as in the legendary Mississippi River flood of 1927. Sometimes it is the
sudden lethality—as in the 1889 Johnstown Flood that killed more than 2,209 people.
Flooding actually occurs from a range of causes and conditions—not always the ones
that first come to mind. For example, few people appreciate that inland flooding
has been the cause of more than half the deaths arising from hurricanes in the last
three decades. Of the 56 people who died in 1999's Hurricane Floyd, 50 drowned from
inland flooding. Torrential rains can accumulate when a storm becomes "stalled"
in a certain location, even hundreds of miles from the coast.
Of course, river flooding is the kind we think of most commonly. Heavy rains or
rapid snowmelt on upstream watersheds cause rivers to rise—more so at chokepoints
or where tributaries converge.
Coastal flooding is also very common. In many places, coastal land is very close
to sea level, and therefore vulnerable. During hurricanes or other large storms,
waves may be much higher than normal, and super-low atmospheric pressure often forces
sea level to rise a dozen feet or more above normal in a "storm surge." When violent
surf and storm surge coincide with normal high tides, the results can be catastrophic.
Less often thought of are the floods that can result from the failure of dams, impoundments,
or other regulatory systems. The Johnstown flood is an example. There are more than
76,000 dams in the National Inventory of Dams, and probably others uncounted.
FEMA, which runs the National Dam Safety Program, says there are 10,400 high-hazard
and 13,300 significant-hazard dams in the United States FEMA says "Emergency Action
Plans" are essential for all of these dams, but that so far some 70 percent still
do not have them. According to the National Performance of Dams Program at Stanford
University, "1,595 significant hazard dams are within one mile of a downstream city."
To keep things in perspective, it is worth remembering that many dams offer major
protection to the public from flood control.
Floods can be a concern even in arid and semi-desert parts of the country, such
as those in the West. Flash floods there are more of a danger because people do
not expect them. Arroyos and washes, or normally dry streambeds and gullies, can
fill with water within minutes or seconds during an intense downpour. Because roads
often follow their contours, they may present danger to people in cars.
A flash flood is really any sudden, severe flood event, and they can have a variety
of causes—although large sudden downpours are the main ones. The effects of a downpour
are worsened when terrain will not absorb water. Reasons vary: soil type (e.g. clay),
lack of vegetation, steepness, extensive pavement (urban areas), frozen or ice-covered
soil, or the saturation of soil by previous rains.
Another cause of flooding in some areas is ice jams. In colder northern areas, ice
sheets form on the surface of a river during cold winter months of low flow. Warmer
weather and higher flows cause the ice to break up into huge slabs that the current
pushes downstream. When these slabs pile up against some obstacle, they form a dam
that causes water to pool upstream—and flooding results.
Floods typically get the most headlines when waters are about to crest. But there
are important post-flood stories that need telling as well. Members of a flood-stricken
community need all kinds of information to avoid pitfalls and deal with problems.
For example, failure of normal sewage and drinking water systems means people need
advice about how to find safe drinking water. They need to avoid pumping out flooded
basements too quickly to prevent water pressure from destroying foundations. They
need to understand and address the problems of mold and mildew in waterlogged buildings.
And of course they need advice on how to connect with disaster-aid agencies.
Issues
The federal government spends several billion dollars on disaster aid in any given
year—a major share of it going to communities hit by flooding. Almost everybody
agrees that people flooded out of their homes need immediate help.
But important issues arise over whether money is better spent preventing losses
before-the-fact than compensating for them after-the-fact. And it is also an issue
whether taxpayer money spent merely to compensate for flood loss does not encourage,
even subsidize, people to remain in harm's way.
Federal disaster aid funds temporary housing for people while damaged homes are
being repaired, money to help repair homes, grants for basic living expenses, etc.,
when these are not covered by insurance. There are also low-interest loans to families,
farms, and businesses to help them repair or replace lost property—as well as unemployment
aid, tax breaks, legal services, and crisis counseling. Another kind of aid goes
to local governments, to help them clean up debris and restore facilities like roads,
utilities, public buildings, and parks.
A different set of FEMA programs and funding are aimed at preventing and mitigating
flood hazards. The most dramatic involves feds partly funding buyouts of flood-damaged
property—to help people buy houses on dry land and the bought property reverting
to uses like parks under ownership of local government. Other federal funds support
measures like physically moving houses beyond the floodplain, elevating them on
stilts, or floodproofing them.
The most important federal effort to address longer-term flood problems is the National
Flood Insurance Program. People in flood-prone areas find it nearly impossible to
get ordinary insurance against flooding—precisely because they are in flood-prone
areas. The NFIP involves a bargain from which both sides benefit. Local communities
must qualify by adopting and enforcing floodplain management ordinances (which might,
for example, forbid building new houses in floodplains). This reduces future flood
damage and federal liability for disaster aid. In return, the federal government
backs flood insurance offered in these communities by participating private insurance
companies. National Flood Insurance is offered in more than 19,000 U.S. communities.
Flood issues spur many policy and political debates at both the local and national
levels. Although the NFIP insists that the program pays for itself, critics often
charge that it is federally subsidized.
The debate is likely to emerge again as Congress and the President struggle with
the 2002 budget. The Clinton administration, following the great Mississippi-Missouri
flood of 1993, shifted a much greater emphasis in funding toward mitigation and
buyouts, to the applause of environmentalists. President Bush's budget proposal
would de-emphasize mitigation in favor of more direct (and politically popular)
disaster aid.
National Weather Service Safety Brochures – Prediction, Floods, Covered Roadways
In August 2002, the National Safety Council partnered with the National Oceanic
and Atmospheric Administration (NOAA) and National Weather Service (NWS) on safety
and health initiatives surrounding the Advanced Hydrologic Prediction Service (AHPS).
The result: a new AHPS brochure that increased awareness of the Weather Service’s
improved river and flood forecasting capabilities and water information across America.
Since then, we’ve continued our partnership to produce:
- A reprint
of AHPS (.pdf; 336K)
Advanced Hydrologic Prediction Service (AHPS) provides
improved river and flood forecasting and water information across America. It’s
useful for navigation, agriculture, emergency response, and recreation. AHPS also
allows for better management and conservation of water. The brochure provides outreach
information about the service with contact information and web links.
- Floods—the
Awesome Power (.pdf; 1.5MB)
Floods—the Awesome Power is a preparedness guide that
explains flood-related hazards and suggests life-saving actions. It helps you recognize
a flood potential, develop a plan, and improve readiness when bad weather approaches.
The brochure also provides links to other sites and organizations that offer additional
information.
- Turn Around
Don’t Drown (TADD) (.pdf; 286K)
Turn Around Don’t Drown promotes awareness about the dangers
of water-covered roadways. False trust in the weight or capabilities of vehicles
can lead to tragic events as drivers attempt to cross a flooded road. The U.S. Department
of Transportation, Federal Highway Administration, endorses this brochure and created
a new road sign: Flooding Ahead - Turn Around - Don’t Drown as a result. The brochure
includes contact information for jurisdictions about obtaining the road sign as
well as web links and telephone services.
Organizations
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