Global Warming…

Global warming is the increase of the Earth’s surface median temperature over time.

Since late in the 19th century the average global surface temperature has gone up .5F and during the 20th century, surface temperatures grew by about 1F.

Predictions for the next 100 years are for a 2.7-8 degree F increase, depending on how much fossil fuels are burned and forest systems are removed.

Global Warming…

An increase in greenhouse gasses is the cause of global warming.

Some effects include: an increase in sea level, difficulties in agriculture, change in rainfall, and changes in the ecosystem which will cause animals and plants to have to adapt or perish.

Floods

• A certain surface is affected by them for an indeterminated period of time.

• They can be

seasonal or sudden.

Floods

Floods are water covering previously dry area. A flood is a very large amount of water that has

overflowed from a source such as a river, lake, and ocean.

They can also have overflowed a broken pipe onto a previously dry area.

The damages after a flood is harsh because everything or parts of things will be under water and the effects of a flood can kill many people.

Kinds Of Floods

Flooding can also be divided into different

categories according to their location:

Coastal Floods

River Floods

Urban Floods

Kinds Of Floods

1. Coastal Floods:

Coastal Floods usually occur along coastal areas.

When there are hurricanes and tropical storms which

will produce heavy rains, or giant tidal waves created by

volcanoes or earthquakes, ocean water may be driven onto

the coastal areas and cause coastal floods.

Kinds Of Floods

2. River Floods

This is the most common type of flooding.

When the actual amount of river flow is larger than

the amount that the channel can hold, river will overflow

its banks and flood the areas alongside the river.

And this may cause by reasons like snow melt or

heavy spring rain.

Kinds Of Floods

3. Urban Floods

In most of the urban area, roads are usually paved.

With heavy rain, the large amount of rain water

cannot be absorbed into the ground and leads to urban

floods.  

The Effect on Floods

Higher surface temperatures and changes in precipitation cause floods in some places, and droughts in others. floods. A rise in sea level and severe rain are two causes of floods.

The Effect on Floods

Long term changes in the hydrological cycle (the flow of water throughout Earth) due to higher temperatures (more evaporation; melting of ice, more intense rain fall) contribute to more floods.

More water vapor in the atmosphere, because the atmosphere is heating up, can cause floods to happen more regularly.

Floods Continued Sea level rising will also contribute to more floods. The sea level is predicted to go up from four inches to

three feet. Sea level rises when the water warms and increases

in amount, or when glaciers and ice melt..

Floods Continued As the glaciers and ice turn into water the sea level

increases and floods could start to last for a longer

amount of time and happen more

Floods ContinuedSea level rising

will also contribute to more floods. The sea level is predicted to go up from four inches to three feet. Sea level rises when the water warms and increases in amount, or when glaciers and ice melt. As the glaciers and ice turn into water the sea level increases and floods could start to last for a longer amount of time and happen more frequently.

Examples and Predictions of Flooding

There are predictions that as a result of

climate change there will be a large increase in

famine by 2050 of 30 million people going

hungry because of less crops caused by

flooding.

One country that suffers from flooding

because of climate change is Bangladesh.

They experienced major flooding in 1998 in

which two thirds of the country was

underwater.

Examples and Predictions of Flooding

There are predictions for this to become

worse with more constant flooding and more of

the country underwater by 2100 if it continues

the same way.

Many coastal cities would be affected,

including Manhattan, San Francisco, New

Orleans, and Miami, and cities around the world

including highly populated ones like Shanghai.

BENEFITS

There are many disruptive effects of flooding on human

settlements and economic activities.

However, floods (in particular the more frequent/smaller

floods) can bring many benefits, such as recharging ground

water, making soil more fertile and providing nutrients in

which it is deficient.

Flood waters provide much needed water resources in

particular in arid and semi-arid regions where precipitation

events can be very unevenly distributed throughout the year.

BENEFITS

Freshwater floods in particular play an important role in

maintaining ecosystems in river corridors and are a key

factor in maintaining floodplain biodiversity

Urban Areas Rural Areas

Massive amounts of erosion can be

accomplished by flood waters.

Such erosion can undermine bridge structures,

levees, and buildings causing their collapse.

Flooding of farmland usually results in

crop loss. 

Livestock, pets, and other animals are

often carried away and drown.

Water entering human built structures cause

water damage. 

Even with minor flooding of homes, furniture

is ruined, floors and walls are damaged, and

anything that comes in contact with the water is

likely to be damaged or lost.  

Flooding of automobiles usually results in

damage that cannot easily be repaired.

Transportation systems may be disrupted,

resulting in shortages of food and clean-up

supplies.

Food grains stored at home or in go-

downs get wet and start rotting.

In under developed countries food

shortages often lead to starvation

Effect of Flood on Urban & Rural Areas

Urban Areas Rural Areas

Gas and electrical service may be disrupted.

Water supply pipes/ system get damaged and

wells get inundated creating shortage of drinking

water.

The affected communities living in

temporary shelters/ resettlements have

limited or no access to safe drinking water,

food etc.

In addition, prevailing unhygienic sanitary

conditions make it conducive for spread of

food and water borne diseases.

Effect of Flood on Urban & Rural Areas

Natural Causes

• Excesive rains.

• Overflowing of rivers, lagoons,lakes,etc.

Human causes• Bad agricultural practice

• Bad infraestructure

• Deforestation

• Urban increase

Most important consequences

• Population mortality

• Economic losses

• Population evacuation

• Infraestructure destruction

Flood Management History in India• Before independence: Damodar experience• 1948: The DVC Act• 1954: National Flood Policy• 1963: Farakka construction starts• 1980: Report of National Floods Commission• 1979-80: Flood forecasting starts• 1999: Report of the National Commission on

Integrated Water Resources Development• 2002: ILR proposals to solve flood problem• 2004: PM’s Task Force on Floods• 2004: Proposal for NE River Valley Authority

The Govt responses• Embankments

• Dams

• Dredging

• Spurs, revetments

• (Flood forecasts, warning)

• ILR

• Disaster Management

• Relief, (insurance)

• Committees

How flood affected area has been going up

State Area prone to floods (m ha) as assessed by

NCF (1980)

10th Plan working Group-2002

Bihar 4.26 6.88

UP 7.34 7.34

W Bengal 2.65 3.77

Arunachal Pradesh - 0.12

Assam 3.15 3.82

Average annual damage due to floods in Bihar(Source: NCF, 1980)

Period Total Area affected, Lakh Ha

Crop Area affected, Lakh ha

Total damage at constant prices, Rs Lakh

1950-65 8.81 4.43 861.92

1966-70 10.82 5.85 1184.08

1971-78 21.30 8.85 4588.57

Average annual damage due to Floods in Uttar Pradesh

(Source: NCF, 1980)

Period Total Area affected, Lakh Ha

Crop Area affected, Lakh ha

Total damage at constant prices, Rs Lakh

1950-65 16.80 7.84 1229.48

1966-70 20.12 10.42 1730.16

1971-78 30.00 16.64 4550.81

Brahmaputra floods in IndiaPeriod Average Annual

Area flooded ( m ha)

Flooded crop area as % of total inundated area

Average Annual no of people affected, m

Average annual damage Rs MTotal Cropped

1953-59 1.013 0.1 8.85 0.86 58.6

1960-69 0.75 0.16 21.33 1.52 75.7

1970-79 0.87 0.18 20.69 2.00 151.8

1980-88 1.43 0.40 28.05 4.55 1445.2

1999-2005 1.07 0.38 35.65 4.586 7171.7