|
August 23, 2002
A: FROM MENTEE LISA R. IN PA
I have never heard of a flood plain, nor have experiened
a flood. I am hoping to research this, you have gotten me
interested in the subject. I will let you know how my flood
plain, and weather research goes. What causes a flood? That
is a question I would like to know the answer to. How come
rain can all come down at one time? Is there some sort of
scientific way to balance this? A few of my friends have a
small creek behind their house. I have asked them what they
know about floods and flood plains. None of them have heard
of a flood plain, but they do say when it rains too much the
creek overflows, and usually floods water into their garage
or basement. I live right out of Pittsburgh, and I do know
when it rains a lot the three rivers flood. I know they are
trying to make manmade dams to hold out the water, from flooding
the streets. I am not sure of what I think of manmade dams,
but I also plan to research that! . I am sorry that I didn't
answer your question, but you have opened my mind up about
the subject. Thank You!
August 23, 2002
A: FROM MENTEE ALEXIS K. IN VA
I have not seen a flood in the States or in my area, but
I have only lived
here for a couple of years. I did see some things in the newspaper
a couple
of years ago...on the Mississippi I think. In Europe I would
hear about
floods that would suddenly sweep through camp grounds and
people would be
washed away and die (mostly France and I think Italy). Why
would there be
camping in flood plains? Could this sillier than building
houses in a flood
plain? In Naples, Italy, there are a tra-zillion houses built
in a "volcano
plain". How smart is that? It seems people will build
wherever there is a
flat space and a water supply. I think everyone must be like
me and assume
that nothing bad will happen to them, then be upset when it
does. I think
contractors and the people who make the laws should be required
to live
where they say it is ok to build. If they can set up other
people for
problems they should have to enjoy along with everyone else!
FLOODS AND FLOOD PLAINS
Floods are common and costly natural disasters
When rivers overflow their banks, or flood, they can cause
damage to
property and crops. Floods are common and costly natural disasters.
In the
United States, the average annual cost of flood damage is
more than $2
billion. Each year about 100 people lose their lives to floods.
Floods usually are local, short-lived events that can happen
suddenly,
sometimes with little or no warning. They usually are caused
by intense
storms that produce more runoff than an area can store or
a stream can carry
within its normal channel. Rivers can also flood when dams
fail, when ice
jams or landslides temporarily block a channel, or when snow
melts rapidly.
In a broader sense, normally dry lands can be flooded by high
lake levels,
by high tides, or by waves driven ashore by strong winds.
Small streams,
particularly in the Southwest, are subject to flash floods
(very rapid
increases in runoff), which may last from a few minutes to
a few hours. On
larger streams, floods usually last from several hours to
a few days. A
series of storms might keep a river above flood stage (the
water level at
which a river overflows its banks) for several weeks.
Weather patterns can determine when floods occur
Floods can occur at any time, but weather patterns have a
strong influence
on when and where floods happen. Cyclones, or storms that
bring moisture
inland from the ocean, can cause floods in the winter and
early spring in
the western United States. Thunderstorms are relatively small
but intense
storms that can cause flash floods in smaller streams in late
summer and
fall in the Southwest. Frontal storms form at the front of
large, moist air
masses moving across the country and can cause floods in the
northern and
eastern parts of the United States during the winter and spring.
Hurricanes
are intense tropical storms that can cause floods in the Southeast
during
the late summer and fall.
Very large floods happen very seldom
The size, or magnitude, of a flood is described by a term
called recurrence
interval. By studying a long period of flow records for a
stream, it is
possible to estimate the size of a flood that would, for example,
have a
5-year recurrence interval (called a 5-year flood). A year
flood is one that
would occur, on the average, once every five years. Although
a 100-year
flood is expected to happen only once in a century, there
is a 1 percent
chance that a flood of that size could happen during any year.
The magnitude of floods can be altered if changes are made
in a drainage
basin. Harvesting timber or changing land use from farmland
to housing
developments can cause the runoff to increase and cause an
increase in the
magnitude of flooding. Building dams that store water can
reduce the
magnitude of floods
Flood plains normally are dry
Flood plains are lands bordering rivers and streams that normally
are dry
but are covered with water during floods. Buildings or other
structures
placed in flood plains can be damaged by floods. They also
can change the
pattern of water flow and increase flooding and flood damage
on adjacent
property by blocking the flow of water and increasing the
width, depth, or
velocity of flood waters.
Zoning restrictions limit flood damage
Flood-plain zoning, which places restrictions on the use of
land on flood
plains, can reduce the cost of flood damage. Local governments
may pass laws
that prevent uncontrolled building or development on flood
plains to limit
flood risks and to protect nearby property. Landowners in
areas that adopt
local ordinances or laws to limit development on flood plains
can purchase
flood insurance to help cover the cost of damage from floods.
Dams and levees can reduce the risk of floods
Flood-control dams have been built on many streams and rivers
to store storm
runoff and reduce flooding downstream. Although the same volume
of water
must eventually move down the river, the peak flow (the largest
rate of
streamflow during a flood) can be reduced by temporarily storing
water and
releasing it when river levels have fallen. Levees are artificial
river
banks built to control the spread of flood waters and to limit
the amount of
land covered by floods. Levees provide protection from some
floods but can
be over-topped or eroded away by large floods. For example,
levees failed to
protect vast areas in the Mississippi and Missouri River valleys
during the
record-setting floods that occurred in 1993.
For additional information:
1-888-ASK-USGS
By Joe A. Moreland, 1993, OFR 93-641
August 22, 2002
A: FROM MENTEE KATHRYN T. IN VA
I have never personally observed a flood plain. However,
I am of the opinion that building on flood plains needs to
be regulated and stopped. Flood plains are normally dry until
flooding occurs. Buildings on the plain can change the pattern
of water flow and cause even more damage to adjacent property
by blocking the flow of water,and increasing the depth, width
and velocity of water. Developers are just anxious to sell
houses and are often indifferent to the damage that this can
cause. It is also irresponsible to buy on a flood plain house
and then take out insurance which in all likelihood will be
used. This places a burden on insurance companies. The bottom
line is that responsible citizens and legislators must work
together to stop building on flood plains.
August 21, 2002
A: FROM MENTOR CHANDRA INGLIS. FOR BIO.
CLICK HERE.
Prior to living in West Virginia, I had never actually
seen flooding other
than on T.V. By the spring/summer of 2001 that had all changed.
The
Southern half of WV experienced some of the worst flooding
the past two
years, and it all happened to the same people both years and
multiple times.
Houses and trailers were completely destroyed, picked up off
their
foundation and transported hundreds of feet. Several feet
of mud deposited
all along the streets and inside of structures. Ruining walls,
carpets and
furniture, beyond salvage. Roads completely washed away and
vehicles lifted
up and re-deposited in trees! People who lost everything,
including in some
cases their loved ones and pets. Complete destruction. If
you want to see
for yourself some of the damage it can do go to
http://www.mcdowellwv.com/photos/2002flood.html.
But through it all the strength, character, goodwill, charity,
tenderness,
and kindness of the West Virginian shone through. I didn't
need Sept. 11 to
show me people who could pull together and help those in need
with donations
of both time and goods. I saw it first hand standing and working
next to
people who had taken vacation time and their free weekends
to go help total
strangers clean their houses, slop buckets of mud from their
basements, and
literally give them the shirts from their backs. That is the
true American
Spirit, when someone is willing to give everything they own,
every free
moment of their time, and every inch of their heart to others
who have lost
everything they had.
So do I think developers should develop in a floodplain? No.
There is a
reason it has that title, it floods, and water can be more
devastating then
you can imagine, until you see it in person. Unfortunately
in some places,
like West Virginia, that is the only place there really is
to build. But if
there is another option, people take it, because flooding
is dangerous and
destructive.
August 20, 2002
A: FROM MENTEE KELLY B. IN PA
No, I have never observed a flood plain. I do not think
that devolpers
should be able to build in them because floods are awful.
My house was
flooded once when alot of snow melted very quickly and it
rained very hard,
the ground just couldn't keep up with it all.
August 20, 2002
A: FROM MENTEE RUTH O. in NH
I observed a flood in the Maasai Plains of Kenya in 1996
when I was going
camping. There wasn’t much damage caused because at that
place people are
so scarce and there are no properties that were to be damaged.
I don’t think
that builders should build on the flood plains because if
they do then the
damages to be caused by the flood increases.
August 20, 2002
A: FROM MENTEE MAGGIE K. IN CT
Yes, I have observed a flood in a flood plain before. It was
a few years ago
I'm not sure what the year was but, it was along the Connecticut
river near
Middletown. most of the damage was caused to trees and plants
but one
restaurant was flooded inside. since whenever there is a like
a foot of
rain the Connecticut river floods the towns have not built
much along this
section.
I don't think that people should build on flood plains because
they are
there so that the water can raise without causing damage.
but if people
build on them then the job of the flood plain has been eliminated.
|
