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IGCSE Geography - Revision guide: Natural Hazards

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Cyclones, Hurricanes - cyclone Nargis in Myanmar - economic, social, environmental impact

Droughts (and desertification)(Chad), in Australia

Floods - Bangladesh 2004 - causes, impact, responses - opportunities and problems of living in a floodplain

Haiti and Christchurch earthquakes

At first blush, the earthquake that struck Christchurch, New Zealand on Saturday was the spitting image of the one that ravaged Haiti in January. Each was a powerful magnitude 7.0 quake, and each occurred on a strike-slip fault near a major population center.

Reports out of Christchurch have been almost miraculous: Though the city suffered extensive damage, not a single person out of nearly 400,000 appears to have died. By contrast, the Haitian capital city of Port-au-Prince was flattened, and a quarter of a million people were killed.

What are the reasons for such a stark contrast ? Read from these two news articles to find out

What is a drought?

drought is a period of unusually persistant dry weather that persists long enough to cause serious problems such as crop damage and/or water supply shortages. The severity of the drought depends upon the degree of moisture deficiency, the duration, and the size of the affected area.

Africa drought causes

Desertification is driven  by a group of core variables, most prominently climatic that lead to reduced rainfall and human activities , institutional and policy factors, and economic factors in addition to population pressures, and land use patterns and practices.

Since most economies of African countries are mostly agro-based, a greater proportion of the desertification problems in rural areas are a result of poverty related agricultural practices and other land use systems.

Inappropriate farming systems such as continuous cultivation without adding any supplements, overgrazing, poor land management practices, lack of soil and water conservation structures, and high incidence of indiscriminate bushfires lead to land degradation and aggravate the process of desertification. 

(excerpt from following document)

Australia drought impact - Economist article

Floodplains

Floodplains are  landscapes shaped by running water. As streams and their larger forms, rivers, flow across the surface of land, they transport eroded rock and other material. At points along that journey, when their flow slows, the material they carry is dropped to create what are termed depositional landforms. Read here

Queensland Flood 2011 - Causes, impact and implications

Fish on the Capricorn highway after the floods. Click this image to see more pictures from Boston.,com

Possible Causes and Impact of the flood

What are the possible causes for the Queensland floods ? Is it changing weather patterns? or planning error in the Brisbane dam? 


Queensland’s devastating floods are the result of heavy rains caused by two normally unconnected weather phenomena.

La Niña is a seasonal interaction between the Pacific Ocean and the Earth’s atmosphere to the east of Australia

Earthquakes - how do they happen ?

What is an earthquake?

An earthquake is what happens when two blocks of the earth suddenly slip past one another. The surface where they slip is called the fault or fault plane. The location below the earth’s surface where the earthquake starts is called the hypocenter, and the location directly above it on the surface of the earth is called the epicenter. Read MORE

What factors determine the destructiveness of an earthquake?

Location, Magnitude, Depth, distance from epicenter, Geologic condition, secondary effects, architecture. Read more details from the Smithsonian blog

Anatomy of a hurricane

Drought in Chad

Drought and child malnutrition in Chad

Flood combat measures

Based on the Floods in Bangladesh: The Way Forward  recommendations :

Short-term

Improve the flood forecasting and warning capacity. 
The Government should also make regular budget allocations for the center for preparing forecasting and issuing warnings to the end users.

Strengthen Disaster Management Bureau (DMB) to provide reliable Damage/Needs assessment quickly that can serve as the basis for restoration and recovery programs. 

The Government should start a disaster response management fund.  Operation and maintenance funds are typically re-directed for restoration and reconstruction of damaged infrastructure

Medium to Long Term

Upgrade the standards of construction for roads, particularly rural roads that serve as a lifeline during the flood period, with proper levels and provision of drainage structures. 

Invest in protection of major towns where population density and property values are high 

Causes of the Queensland flood

The volatile conditions in Australia are being blamed on a weather system called La Niña.

La Niña is a natural three to six year cycle which results in a cooling phase in the eastern Pacific just off the coast of Peru.

A drop in sea temperatures of only a degree or so can cause a dramatic change in weather patterns around the world.

This year the cooling phase has caused severe rain in parts of Australia which have suffered drought conditions for several years.

La Niña is the opposite of El Niño which causes a rise in sea temperatures in the same area.

It means the heat and energy that is found in the tropics is transferred away from eastern side of the Pacific to western side. 

Typically La Niña - sometimes described as the quiet sister - is not as severe as El Niño but scientists say we are currently experiencing a strong La Niña phase.

news source : channel4.com

Impact of an earthquake

Economic development of the location

Urban or rural area

Distance from epicentre

Weather and season

Time of day and Day of week

Emergency services and earthquake response plans

Landscape and rock type

Cyclone Nargis in Burma

Cyclone Nargis moved across southern Myanmar on the evening of May 2, 2008, leaving a trail of death and destruction before petering out the next day. It devastated much of the fertile Irrawaddy Delta and Yangon, the nation's main city. Nearly 85,000 people died. 

The Government of Myanmar, the Association of Southeast Asian Nations (ASEAN) and the United Nations in the first comprehensive report inputs

- It estimates the cyclone killed over 84,530 people, with a further 53,836 still reported missing.

- The cyclone wiped out the livelihoods of families overnight, flooding over 600,000 hectares of agricultural land, killing up to 50 per cent of draught animals, destroying fishing boats and sweeping away food stocks and agricultural implements.

- in mid-June, 55 per cent reported having only one day of food stocks or less, and have relied in part on the steady flow of relief supplies.

- The total economic losses amount to about 2.7% of the projected 2008 GDP, with the effects of the cyclone concentrated on a region important for agriculture and fishing in Myanmar. source

Australia - drought

Droughts occur when there is not enough water for people, plants and animals for an unusual amount of time. Australia’s current drought started in 2003 and has been called the 'Big Dry'.

What causes drought?

Australia is often affected by droughts because of our geographyand changeable rainfall patterns.

The image below shows that our continent is located in a subtropical area of the world that produces dry, sinking air that creates clear skies and little rain. For most of the country, our rainfall is very low and irregular.

Another cause of drought in Australia is from the El Niño weather pattern. When there are El Nino weather conditions, Australia becomes drier than normal and the chance of rain decreases.

from the Australian government emergency management website

Bangladesh Floods - 2004

What are the causes ? Melting snow ? Soil erosion ?