Floods
INTRODUCTION
A flood is usually caused by rain,
heavy thunderstorms, and thawing
of snow.
Its considered to be a temporary
condition of two or more acres of
dry land either:
• Overflowed with inland or tidal
waters
• Rapid or runoff of surface waters
• Mudflows
How does Flooding Start and end?
The shore or land by or surrounding a body of water
erodes and this erosion causes waves currents that
result in a flood.
Flood disasters have been increased because of the
expansion of settlements and growth in floodplains.
Floods could be slow or fast but usually occur over a
matter of days.
After the water eventually goes down or dries up. On
coastal floods, low tides and high tides makes a
change in heights.
Why does it occur??
A flood is too much water in the wrong place.
Sometimes a flood occurs from :
• Sewer (drain) backup
• Collapse of land along the shore of a lake or
another body of water. This results in waves
or currents during a flood
Flooding is the most worldwide natural disaster. It occurs in
every country and wherever there is rainfall or coastal
hazards.
They are most likely to happen in tropical areas and tsunamis.
Most common floods happen around the world’s
largest/greatest rivers.
Believe it or not, smaller rivers could cause more damage
even though people don’t pay as much attention to them.
Most Flooding occurs during the beginning of spring.
Characteristics of a Flood
A number of criteria determine the dangers of a flood. The University of
Wisconsin have came up with the following criteria such as depth of
water, duration, velocity, rate of rise, frequency or occurrence, and
seasonal.
• Velocity- high velocities of flow create erosive forces and can do things
like destroy foundations.
• Depth of Water- floatation, failures on foundation, vegetation survival,
etc..
• Rate of Rise- is the rate at which the water level increases.
• Seasonal- the land during growing season, the effects on agriculture
production and other things like that.
How Does it Effect People?
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The amount of people
effected by floods
from 1999- 2000 is
reported to be
approximately 1.5
billion.
In the U.S. alone there
are 10 million people
living in areas that
could flood.
Precautions to Take
To remain safe from floods you
need to know when and how to
deal with them.
Lives could be saved by having
more warnings of floods for
places in threat.
There are things used for antiflood
protection and it makes your
house, yard and much more, safe
and protected when a flood
arrives. They can be used over
and over again.
Flood Protection Equipment
This is a Door Flood Barrier. Its used to fit
and seal your door.
This is a free standing door barrier. The
difference with this one is you can still have
use of the door as well.
Modular Flood Barrier is the highest level of
protection . Its installed to protect your
whole property from high bodies of water
during a flood.
Predictions of a Flood
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Deep Snow can melt into a lot of water.
It usually floods because of rain or
rapid warm temperatures.
Frozen ground won’t absorb as much
water, the rain and/ or snow causes
flooding on frozen ground.
Full reservoirs- Reservoirs are very big
and are man-made to hold water for
drinking or irrigation. It won’t absorb
anymore water f full and it causes it to
overflow.
High River or Stream Levels- melting
flows into a full river and overflows on
banks.
Government and Emergency Team Aid
There is an organization called World Meteorological
Organization. It promotes flood management and water
resources management. They have successfully guided and
promoted international development of meteorology and
hydrology. They give forecasts and warnings.
The government’s responsibility of fixing things during a
flood are for example :damaged roads, buildings,
telephones, and electricity.
This is the natural disasters in U.S. and the cost in millions.
Effects on the Environment
Sometimes it’s a good thing when a flood occurs. The
environmental benefits of flooding are fisheries, wetlands, and
irrigation.
Flood plains have one of the highest development potential when it
comes to economic development.
It also makes a mess of the environment. The soil becomes poor
because the oxygen is limited due to so much water. The pH in
soil decreases, rate decomposition of organic matter in flooded
soil tends only to be half that unflooded soil
Trees are effected as well. It effects the height, age, vigor, roots,
and species.
During the growing season flooding is very harmful especially to
woody plants compared a flood in a dormant season.
Floods could carry chemicals from agricultural fields, sewage,etc.
and can’t handle large bodies of water.
Crops die because they can’t survive because of the conditions.
Flash Floods
This is a picture of a town
after a Flash Flood
Flash floods happen in a short time,
they have a great volume of
water, and are local floods.
The runoff of intense rain results in
high flood waves.
Flash floods result in failure of
dams and more.
It usually happens in desert areas
and mountain regions.
They are a threat in steep land,
high runoff rates,
thunderstorms, and narrow
streams.
River Floods
Riverine floods are caused by
melting of snow and
precipitation over large
areas. They take place in
rivers. Floods in large
rivers take hours to days.
The ground conditions
effects the runoff.
Coastal Floods
Venezuela in December of 1999.
Coastal floods are caused by tides,
storms, tropical cyclones, or
tsunamis.
They happen in the ocean and
effects the general public and
maritime interests along the
coastline.
They are caused by heavy surf,
tidal piling, and storm surges,
Other factors are tidal cycles,
behaviors of the storm, river or
stream runoff, no offshore reefs
or other barriers, and high
winds.
Urban Floods and Ice Jams
Urban floods are when the land is
turned from fields or woods
into roads and parking lots.
Since this happens it can’t
absorb the rainfall.
During the urban floods all the
streets become rivers and
basements become full of
water, they are death traps.
Ice Jam is floating ice that adds up
at a man-made or natural area
and stops the flow of water.
This causes the area to flood.
Lakeshore Floods
Lakeshore floods affect the general
public as well as some areas of the
Great Lakes.
These floods extend from the beaches
to rivers that flow into lakes. The
extent of the flooding is dependant
on surrounding the shore terrain.
The causes of these lakeshore
floods are seiches in the Great
Lakes.
The Webster dictionary’s definition of
Seiches is:
The flow of periodically changing
direction of the surface of a
landlocked body of water (like a
lake) that varies from a few
minutes to several hours.
Deaths during Floods
Floods often result in death, especially along
river banks and low-lying areas.
Floods kill more Americans than any other
natural disaster each year. You may be
surprised but only 6 inches of fast moving
water can sweep a person off their feet and
cars will float of move in only two feet of
water.
Red River Valley Flood
The Red River flood crest emptied into
Lake Winnipeg on May 8th, 1997. This
ended the largest flood in Red River
Valley ever recorded
The red river valley occurred in 1997 in
Minnesota. That winter eight harsh
blizzards hit Red River Valley. When
the snow started to melt the river started
to rise.
The flood preparation was made for a 49
foot flood crest. The flood was actually
54.33 feet on April 22, 1997.
Areas that were in immediate danger was
evacuated on April 18th, people were
evacuated from entire cities on the 19th.
On the 24th the government officials started
to let people back in dry areas.
Most of the clean-up was done by the end of
1997 but they were still building
houses, basements, and other buildings
in 2000.
Mozambique, Africa Flood
In Mozambique on March 3rd, 2000 an
awful flood had destroyed three
villages.
Around 1 million people needed
shelter, food, and medical care.
Thousands of people remained on roofs
and rat-infested trees.
Rescuers had saved 12,000 people
from flood waters after starving for
a week.
15,000 remained in Save River Valley,
stranded and nowhere to go.
The government has estimated 1
million people have been displaced
by floods since the beginning of
February 2000.
Bangladesh Flood
Bangladesh is a country with many rivers.
Flooding in this area is common and
necessary so it could fertilize from
deposits of fresh alluvium.
Fresh alluvium is soil that is deposited by
moving water.
In the fall of 1974 flooding was extended
over one half of the country and stayed
this way for over a month.
At least 1,200 people had died in the floods
and 27,500 died from diseases and
starvation. 425,000 houses were
destroyed and destroyed agriculture.
The cost of damages were 325.9 million
in U.S.
36 million were effected by this huge flood.
Nova Scotia Flood
This horrific storm dumped around 100 millimeters of rain trough the
Atlantic on Monday March 3rd, 2003.
It was caused by melting snow, rain, high tides, and freezing rain
which caused streams and rivers to clog and trees to break.
Thousands of people have had to bail out of their homes.
The overall damage for provincial roads and bridges is estimated to
be 10 million dollars.
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Nova Scotia’s Transportation Department said 47 bridges have been
destroyed or damaged by flooding. Two hundred roads have been
damaged in the province as well. Major culverts were ruined and oil
tanks ripped from homes.
Emergency tenders are being sent out to get repair work started as
soon as possible.
Unfortunately a seniors couple died when that car got swept away
from a flooded road of Lahave River.
This flood was one of the worst floods Nova Scotia has had in years.
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These are pictures of different parts of Nova Scotia after the flood
Northern California
Tunisia
Zambia Southeastern Africa
Brazil
Madagascar
Indonesia
Northern
Australia
Western Australia
This is where the latest floods have occurred in the world. It
was taken by NASA satellite.
Flood Insurance Rate Map
A Flood Insurance Rate Map (FIRM) is a map to
show flood risk zones and flood elevations.
LEGEND
SPECIAL FLOOD HAZARD AREAS INUNDATED BY 100 YEAR FLOOD
ZONE A
No base flood elevations determined
ZONE AE
Base flood elevations determined
ZONE X
Areas of 500 year flood; areas of 100 year flood with average depths of less than 1 foot or with drainage areas less than 1 square
mile; and areas protected by levees from 100 year flood
OTHER FLOOD AREAS
ZONE X
Area of 500 year flood; areas of 100 year flood with average depths of less than 1 foot or with drainage areas less than 1 square
mile; and areas protected by levees from 100 year flood
OTHER AREAS
ZONE X
Areas determined to be outside 500 year flood plain
ZONE D
Areas in which flood hazards are undetermined
EXPLANATION OF ZONE DESIGNATIONS
ZONE A
Areas of 100 year flood; base flood elevations and flood hazard factors not determined
ZONE A1- A30
Areas of 100 year flood; base flood elevations and flood hazard factors determined
ZONE B
Areas between limits of the 100 year flood and 500 year flood; or certain areas subject to 100 year flooding with average depths less
than (1) foot or where the contribution drainage area is less than one square mile; or areas protected by levees from the base
flood
ZONE C
Areas of minimal flooding
ZONE V1 – V30
Areas of 100 year coastal flood with velocity (wave action); base flood elevations and flood hazard factors determined
Flood Hazard Boundary Map
A Flood Hazard Boundary Map(FHBM) is for an
area and outlines the special flood areas but
doesn’t include and elevation information. It
shows flood insurance risk zones. Its for 100-500
year flood areas.
These are pictures of floods in Texas. It was the worst
flood since 1998 in Texas. 22 people were killed
The NSDU extension service says:
These are people from the red cross
in China reaching victims in their
boat.
DURING A FLOOD
Listen to the radio for further information.
Fill bathtubs, sinks and jugs with clean water in case water
becomes contaminated.
Bring outdoor belongings, such as patio furniture, indoors.
Move valuable household possessions to the upper floors or to
safe ground if time permits.
If you are instructed by authorities, turn off all utilities at the
main power switch and close the main gas valve.
Join with neighbors and volunteers to put sandbags or other
protection in place. Stack sandbags away from the outside
walls of houses to prevent floodwaters from entering.
Do not attempt to walk through moving floodwaters. If they
are moving fast enough, water one foot deep can sweep you
off your feet.
Do not attempt to drive over a flooded road. Turn around and
go another way.
Click here
Flooding
As you can see flooding is not only a reoccurring
natural disaster its also very dangerous!!
Flooding is costly and threatening…. This is no
joke!!!
Bibliography
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http://www.fema.gov/hazards/floods
www.und.nodak.edu/dept/library/Collections/og1351.html
http://wmo.ch/apfm
http://www.antiflood.com
www.canada.com/news/story.asp?id=275CB01A-CDDC-47AOO-93/D5274D7244
www.ssl.sabah.gov.my/clh/environment/flood/flood_effects.html
www.na.fs.fed.us/spfo/pubs/n_resource/flood/toler.htm
www.hydrology.com
http://dmc.engr.wisc.edu/courses/hazards/BB02-06.html
novascotia.cbc.ca/regional/servlet/View?filenames=ns_floodcost20030402
www.usatoday.com/weather/wfldfac.htm#three
http://ks.water.usgs.gov/kansas/pubs/fact-sheet/fs.023-000.html
www.hollandsentinel.com/stories/030400/new_slow.html
www.property-appraiser.lee.fl.us/GISDepartment/FIRM1.htm
www.savethechildren.org/press/pr_bangladesh.html
www.personal.psu.edu/users/a/l/alal64/projects/geog121/project5/firm_example.htm
www.nws.noaa.gov/om/brochures/ffbro.htm