The document discusses floods, defining them as an overflow of water onto normally dry land, caused by factors like heavy rainfall, snowmelt, or coastal storms. It outlines the characteristics of floods, their impact on people and the environment, and the measures for flood risk management and protection. Additionally, it provides case studies of notable floods, emphasizing the importance of preparedness and the risks associated with flooding.

1. Floods
Floods

2. 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

3. 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.

4. 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

5. 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.

6. 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.

7. How Does it Effect People?
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.
QuickTime™ and a
Photo - JPEG decompressor
are needed to see this picture.

8. 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.

9. 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.
Flood Protection Equipment

11. Predictions of a Flood
• 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.

12. 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.

13. This is the natural disasters in U.S. and the cost in millions.

14. 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.

15. Flash Floods
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.
This is a picture of a town
after a Flash Flood

16. 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.

17. Coastal Floods
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.
Venezuela in December of 1999.

18. 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.

19. 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.

20. 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.

21. Red River Valley Flood
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.
The Red River flood crest emptied into
Lake Winnipeg on May 8th, 1997. This
ended the largest flood in Red River
Valley ever recorded

22. 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.

23. 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.

24. 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.
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.
QuickTime™anda
Photo-JPEGdecompressor
areneededtoseethispicture.

25. QuickTime™ and a
Photo - JPEG decompressor
are needed to see this picture.
These are pictures of different parts of Nova Scotia after the flood

26. This is where the latest floods have occurred in the world. It
was taken by NASA satellite.
Northern California
Brazil
Tunisia
Zambia Southeastern Africa
Madagascar
Indonesia
Western Australia
Northern
Australia

28. Flood Insurance Rate Map
A Flood Insurance Rate Map (FIRM) is a map to
show flood risk zones and flood elevations.

30. 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

31. 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.

32. These are people from the red cross
in China reaching victims in their
boat.
These are pictures of floods in Texas. It was the worst
flood since 1998 in Texas. 22 people were killed
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.
The NSDU extension service says:

33. Click here

34. 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!!!

35. Bibliography
• 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