floods and drought - geography

7/30/2019 Floods and Drought - Geography

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Floods and Droughts

By: Adam Campigotto,

Dane Macri, and Matt Morencie


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What Causes Floods?

Floods are an excess ofwater that covers land that

is normally dry.

This can be due dam orlevee failures, more rainthan the landscape can

dispose of, torrential rains

caused by storms, rapid

snow melts, or a blockedriver.


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What Causes Droughts?

Droughts are caused by alack of precipitation in anarea resulting from weakor less frequent storms and

other weather systemsthan normal.

Most major droughts lastfor months or years.

What is considered adrought in a rainy locationmay be enough

precipitation for anotherregion.


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When Do They Occur?

Floods can occur any timeof the year.

Floods occur primarily inthe spring season due to

ice and snow melting andfrequent storms.

In some countries, thereare monsoon seasons, atime of great rain, whenfloods often occur, then adry season, when droughtconditions occur.

Droughts can occurany time of the year.

In North America,

droughts occur mostoften between March

and September, when

it is often dry and hot.


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Where Do Floods Often Occur?

Floods occur all overthe world, except for

in Antarctica.

Highlands are alsounlikely to be struck

by flooding.

They often occur inurban areas where

water cannot drain

into the soil properly. Floods usually affect

floodplains, low lying,

flat areas near large

bodies of water.


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Major River Floods in 2002

The areas in red are where river floods have occurred this year.


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Where Do Droughts Occur?

Areas that have frequentand severe droughts areshown on the map as thedarkest shaded areas, andless sever droughts are the

lightly shaded areas.

They usually are mostsevere around the 30latitudes, where dry, cool

air is falling. Asia, many Africancountries (I.e. Kenya,Ethiopia, Somalia), aremost often affected by

droughts.

Humid areas are proneto short term droughts,

whereas arid regions are

prone to long term

droughts.


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Have They Occurred Near Here?

There have beenfloods in Windsor.

The Detroit River and

River Canard haveexceeded their natural

boundaries during the

1970s.

In Windsor, there havebeen many droughts,

but none of great

severity. In 2001, Windsor had

a drought season,

affecting River

Canard, crops, and

other plants.


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Recent Floods.

Morocco hasexperienced a flashflood recently, killing

over 60 people. Theflood has cause $1.75million in damages.

Another flood has

recently hit CostaRica, leavingthousands homeless.


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Recent Droughts.

Australia has recentlybeen through droughtconditions. The drought isoccurring around Sydney.

Fires have begun due tothe dryness of the land.

Ethiopia is also in adrought, and is expectingover 11 million people to

be without food next yeardue to crop failures.


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Destruction by Floods

Floods can cause major structural damage tobuildings, kill plants and animals, destroys

habitats, and removes soil.

Floods cause many deaths and drown many plantsand crops, and hundreds of millions of dollars in

damage.

Many nutrients in topsoil arebrought downstream ordeposited in the ocean.


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Hazards of Floods

There are 6 categories totell how severe floods arein a region.

They are depth of water,

duration, velocity, rate ofrise, frequency, andseasonality.

Frequency is how oftenfloods occur in an area,which depends greatly onthe topography andclimate.

Seasonality is the time of

year floods often occur.

Depth is simply how deepthe water is.

Duration is how long thewater lasts for.

Velocity is how quick thewater is moving; the fasterit moves the more damagedone.

Rate of rise is how quicklythe depth of the waterincreases. (importantwhen giving warnings toevacuate areas)


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Destruction by Droughts.

Droughts cause major damage to crops andanimals, especially if they occur during theregions growing season.

During a drought not enough water is provided tosupport living things. Crops can decrease 10%-20% during a drought.

Droughts affect reservoirs, water supplies, water

tables, and topsoil. Water levels drop, and topsoilbecomes dry and less favourable to plants.

Areas that are in a drought are more likely to havewildfires than other regions.


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How Often Do They Occur?

Floods can occur anytimeof the year.

It is difficult to predictwhen floods will occur in

many regions. It may bedecades between floods incertain areas.

Certain regions floodseveral times a year (5 ormore).

There are an average of100 to 150 extreme floodsannually, world-wide.

Droughts can occuranytime of the year.

Near the equator,

regions mayexperience 2 or more

droughts per year.


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Weather That Causes Floods.

Floods are caused by melting snow and ice,severe storms, hurricanes, tropical storms,

monsoons, or prolonged or sudden rain fall.

El Nio is a major contributor to floodingglobally.


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Monsoons, Floods and Droughts

Monsoons are seasonal winds that bring heavyrains one part of the year and dry air the other.They occur in parts of Africa, Australia, Asia, andSouth America causing floods in the wet season,and droughts in the dry season.

During the wet season, the land is heated causingthe air to rise, creating a low pressure area. Air

currents coming from above a body of water rushin to replace the warm rising air. These windsfrom off the water carry much water causingheavy rainfall and, usually, flooding.


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During the winter, when the water is warmer thanthe land, a low pressure system builds over thewater, and a high pressure system builds over theland. As the air currents move from the high

pressure above the land to the low pressure abovethe water, little precipitation is brought to the land,

because the air is rushing from an area above land,which will have little moisture.This causes the dry season; thetime when many droughts occur.


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Weather That Causes Droughts.

Droughts occur when weak or less frequentprecipitation occurs than normal.

When dry air cools and falls, lowering relative

humidity and the level of precipitation, conditionsthat can bring droughts occur.

During a drought not only is there littleprecipitation, but the

moisture from the soil mustalso leave into theatmosphere throughevaporation and transpiration.


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THE END

Thanks for your

Attention!!

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