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1 River environments
2 Coastal environments
3 Hazardous environments
4 Economic activity and energy
5 Ecosystems and rural environments
6 Urban environments
7 Fragile environments
8 Globalisation and Migration
9 Development and human welfare
6. Short term and long term impacts of natural disasters
6. What are the short term and long term impacts of natural disasters?
(comparative case study of tropical storm in LIC and HIC)
So far we have looked at the characteristics, distribution and causes of our 3 natural hazards. The characteristics are closely linked to the effects of these disasters. What they are like and what they do and the kind of damage they cause are closely related.
We have also looked at when examining recent hazards events is their impact on the human beings who come across them. Sometimes these impacts can be quite mild and sometimes they verge on disastrous. As these impacts are not necessarily linked to the nature of the hazards themselves but more to do with how the humans prepare for the hazards and how they respond when it happens (but more about preparation another day).
You might assume that the impacts would tend to lighter on HIC countries than LIC countries.
This is because
They have enough money to have well run and well resourced
roads and railways
police and armies to help with sorting out and clearing up
They have planned for the possibility of disaster and have planning and building regulations that take this into account.
To a large extent this does tend to be the case. But there is a financial downside. HICs do spend an awful lot more money on their homes, their public building, roads, water treatment, power and communication systems, and so when there is severe damage, these are considerably more expensive to replace and repair. However, politically, delaying and permitting any disaster to impact for long on their population is not thought upon kindly by the electorate. So HICs have to buckle down and pay up as quickly as possible and are sternly criticised when they don’t.
[NB 17th Nov 2009 Cumbrian floods UK – the next day all the government departments were falling over themselves providing extra funds to rebuild bridges etc. While there are still people living in caravans from the 2007 floods in that area]
Impacts of Volcanoes
are so hot and choking that if one is caught in one the person will certainly be killed. Because these flows are very fast they cannot be out-run. If a volcano that is known for producing pyroclastic flows is looking like it may erupt soon, the best thing is to evacuate all the people living near the volcano. Everything in its way will be damaged or destroyed. This includes buildings, roads, crops, stock (animals) and woods.
are mudflows formed by the mixing of volcanic particles and water which often cause a lot of environmental and economical damage. The direct impact of a lahar's turbulent flow front or from the boulders and logs carried by the lahar can easily crush, abrade, or shear off just about anything at ground level in the path of a lahar. The force of a lahar is so big that buildings and valuable land may become partially or completely buried by one or more cement-like layers of rock debris (even if not crushed or carried away). People caught in the path of a lahar have a high risk of death from severe crush injuries, drowning or asphyxiation. If a volcano known to produce lahars looks likely to erupt soon, the best thing to do is to evacuate the people involved.
burn or bury everything they come across. They can run over houses, roads, and any other structures. The speed, and the power of the lavaflow depends on the type of lava. Aa lavas for example can leave the vent with a speed of about 50km. The surface the lava flows on will be changed by very quickly emplacing a layer of very new and hot rock onto the pre-existing terrain. The pre-existing terrain is destroyed by the lava flow. People rarely get killed directly by lava. However, lava flows may start fires which are a lot more dangerous for the environment around the volcano.
is a volcanic rock which is exploded from a vent in fragments less than 2mm in size. Volcanic ash-particles are like small sharp glass-particles that damage anything they come across. Because volcanic ash can fall on many things it's very harmful to the environment around the volcano. During heavy ash-rains houses and buildings may collapse, people and animals may die by lack of oxygen. Ash clouds may provide big problems for aviation. When airplanes fly through an eruption cloud a range of damage may occur depending on the concentration of volcanic ash, gas aerosols in the cloud and the actions taken by the pilot to exit the eruption cloud.
Summary of negative impacts:
Short term impact
: Once there is an orange or red alert, parts or all of the volcano will be evacuated and the people will have to leave, as almost all of the possible outcomes are a serious life threat. They should board up their houses and take as much as they can with them.
Long term impacts
: Their land/crops/livestock/homes may be enveloped in ash, burn by larva or destroyed by the force of lahars or pyroclastic flow.
However there are
positive long term impacts
of living on a volcano. Within a relatively short time, the ash breaks down and forms good, deep fertile soil, which one reason why people tend to return.
The closeness to the surface of magma, means that renewable energy is often readily available from geothermal energy.
Also the magnificent scenery is a strong attraction for tourists, once things have settled down and so a good living can be made form that.
[But more about this in detail later]
Impacts of Earthquakes
The major effect of an earthquake (unless it happens under the sea and is a big one) is the shaking. The amount in any one place depends on
How deep the focus is
How far you are from the epicentre
The nature of the under lying rock – loose and/or soft rocks transfer the vibrations to a greater extent than granite for example.
The impact links to the magnitude:
However, the impact is likely to be less in an HIC than in an LIC
HIC’s are likely to have buildings designed to withstand earthquakes. While LICs often can't afford to build new structures to the same standards. Consequently the building damage and loss of life will be reduced in HICs.
HICs have disaster plans, and frequent school drills and well equipped and trained emergency serices. While most LICs don't have enough money to develop emergency plans, buy the response equipment and training needed, and conduct very expensive training exercises involving thousands of people. So avoiding injury and responding to disaster is less evident in LICs.
HICs can afford to keep emergency stocks of medicines, tents, blankets, food, water, and communications equipment just in case and so they can respond quickly to needs for food, water and medicines. While many LICs struggle to provide these facilities for normal use. Consequently recovery may be quite quick in an HIC but much slower in an LIC.
A speedy response is essential to save lives. HIC can bring in speciality transport and supplies quickly from their own reserves. LICs have to waitfor international help to arrive. Consequently the death tool in LICs is much higher.
Urban or Rural Area
is another variable: high density, tall building, a large population are always in more danger than a dispersed rural population. However, reaching a rural population will take far longer. So you are more likely to come to serious or mortal harm in a city, but the impact on you in a rural area will be longer, especially a remote rural area in an LIC.
Weather and Season
: if it is winter and housing has been destroyed, then this could lead to more people dying of cold or wet, risking of hypothermia, frostbite and illnesses caused by long exposure to dampness and cold. Bad weather also hampers rescue efforts and makes recovery from the disaster much harder. But quakes that strike in warm dry weather also have specific problems, but these are more associated with hygiene. High temperatures make it harder for trapped people to survive in the rubble because although you can live a long time without food, you die quickly without water. Heat also speeds up the decomposition of the bodies of those who die which, like broken sewer pipes, uncollected rubbish and dead animals, quickly become sources of bacteria and vermin that spread diseases. It only takes one dead animal/person in a water supply to make that water totally undrinkable.
Time Of Day and Day Of The Week:
The day of the week is an issue mainly in built up areas such as cities. During the working week many people are gathered in towns and cities, and huge numbers will be working in vulnerable buildings such as high rise office blocks. During the weekend, however, those people stay at home and are dispersed over a much wider area. The collapse of a house may kill or injure a single family, whereas an office block collapsing could kill hundreds of people.
The time of day is important too. For example, most people are at home in bed at 3am, so they are spread out across a wide area, and lying down and even protected from falling plaster etc by their bedding. Those same people at 8am would be driving cars, sitting on trains or busses, or walking around. They would be far more vulnerable to the earthquake effects.
The impact of revolving tropical storms
The main effects of revolving tropical storms – namely hurricanes, cyclones and typhoons – increase a with the category of the storm
What are the likely effects and impacts from a serious tropical storm?
Loss of life
: due to drowning or being hit with flying objects or buried under rubble of buildings. Later this might occur due to disease or infection as a result of lack of clean water, contamination by sewage.
Loss of buildings:
This creates widespread homelessness. Homes that are flooded, even if the winds do not cause a lot of damage, will take a long time to dry out. Then the cleanup has to begin, ridding the property of remains of flood water, together with anything that got mixed up in it, takes a long time. In addition loss of schools which will disrupt the education for many. Damage to health facilities will increase the overall loss of life and prevent people being treated rapidly for lesser injuries which they might have otherwise recovered from. Building also hold shops, offices and other businesses If these can no longer be used, then there will many jobs lost. Damage to government offices and other organisations such as police and social services will make it much harder for their officers to do a good job, access their records and so on.
Loss of communication
: Communication includes transport networks, telephone, radio and television transmission . Loss of roads, bridges and railways will make it hard to get in supplies to help those people who have lost their homes, have not got clean water or food and need medical help. Telephones, radio and TVs are the main means for people to hear what is going on, what need to do and reassurance about what help is on the way. Telephones is for communicating their needs and keeping in contact with their familes. Without some or all of these, people feel very isolated and coordinating responses to the disaster becomes very difficult.
Loss of power
: If the electricity cables are blown down, food will rot if the freezers are not working. There will be no lighting or heating nor means to heat water to start cleaning up.People would not be able to get TV/radio even if they are working (see above)
Loss of water/sewage systems:
In warm weather, in particular, the need to remain hydrated is very important. Once the fresh water is finished, people will drink less clean water, that may be contaminated by sewage, and leave themselves open to all sorts of diseases. If the area is flooded, the water and sewage systems are often themselves flooded, leading to all sorts of liquids becoming mixed up!
Loss of farm land/crops/stock
– There is an immediate loss of food and livelihood of the farmers and their workers. If the land has been inundated with salt water, it is possible that it will never grow the same crops again, as many crops cannot tolerate salt. Loss of stock (cows, chickens etc) can be hard to replace and in the meanwhile the farmer no longer has milk, eggs etc to sell. If the area was highly productive and an important source of food for those living in the towns and cities, then famine is a very real threat.
Case Study: Cyclone Sidr
Where did it happen?
Bangladesh is at the North end of the Bay of Bengal. Cyclones that form over the Indian Ocean sweep up the Bay of Bengal and fly over Bangladesh, before dying out over the land.
Much only 1 m above sea level – very densely populated – many people involved in farming/fishing in the delta area, which supplies much of the countries food.
When did it happen? What was it like? The physical effects?
15 November 2007
Winds of 140km per hour, 5m surge – category 4 on the coast. Flood water inundated coastal region.
Deep floods ruined farm lands and forests, high winds damaged trees, blocked roads and destroyed houses. .Environmental sensitive areas, e.g. the Sundarbans mangrove forest, a world heritage site which is home to the Bengal tiger was devastated.
What were impacts on the humans? On the economy?
Only about 3500 died. Low compared with 1991 (153,000). They lost their homes and their crops and many animals. But their lives were saved in a great many cases. Many people did receive injuries. 7 million lives were affected. Water and power supplies largely lost in the coastal areas.
Arable land swapped and crops were lost. Most housing was lost or severely damage estimated at 1.2 million units. Prawn farms lost.
How well were they prepared to reduce the impacts of cyclones?
More about this will be added later. But they had been raising some river banks. They had built a number of cyclone shelters after the last big disaster and they had developed a system of warning vulnerable populations of future events.
What were the pre storm responses?
Warnings were received from satellites. Alerts were sent out by mobile telephone. Where there was no TV or radio, police went out in cars, auto-rickshaws and used megaphones to warn people. 10s of thousands fled inland, taking their animals and a few possessions. Fishermen were called to port and airports were closed. Rail services and ferryboats were stopped.
What were the short term responses?
Relief crews tried to reach the damaged communities but this was difficult as roads/ railways were damaged. This caused local people to feel very angry. Aid agencies got in emergency help quickly, but given they had to come in from outside this did take days not hours.
What were the long term responses?
People had to survive in temporary shelter even tho’ the monsoon was coming – only plastic sheeting for many. Paddy fields were unusable for sometime. Water and power supplies were slow to be returned
More detailed information can be found in the class powerpoint –
Y10Ge UA3.4 Case studies Nov_Dec PP.ppt
Documents and other items:
katrina brilliant but short.pps
Hurricane Katrina Fact Sheet2006.doc
Cyclone Sidr Fact Sheet.doc
must read article
on the blog - one from New Orleans 4 years on in August 2009 - and Mayer Nagin is still there!One from Bangladesh 2 years on. They both still have a lot to do!
Case studies of Katrina will be added later
A short useful review of Katrina
A podcast from Bangledesh 3 months after Cyclone Sidr
How do the impacts of cyclic tropical storms differ between LIC countries and High income countries?
In general in an LIC there will be
More deaths as they will be less well prepared and communication is poorer
More damaged housing as the housing structure is not designed to withstand storms as well as houses in HICs
Both are likely to suffer water and power loss, but returning it to working order will be much slower in LICs as they have less money and expertise readily avaialbe
There will be more srious and long lasting injuries and sickness as a result of the storm, as the medical care will be less sophisticated and there are fewer qualified staff.
Other aspects of infrastructure will be more damaged and will take longer to fix, like roads, schools, railways.
Getting immediate help in will be slower, as much of it will be supplied by Aid agencies that will have to bring in supplies from other countries, whereas most HICs have a ready supply of goods, which can be quickly brought using helicopters, which are often in short supply in LICs.
Comparing and contrasting the impacts of Hurricane Katrina and Cyclone Sidr
Hurricane Katrina was a category 3 storm by the time it reached landfall whereas Cyclone Sidr was a category 4. This means that the effects of the storm were considerable more severe for Bangladesh (wind speeds of more than 200km/h) that they were for New Orleans (at around 175km/h.)
Both events had a similar death rate in the low 1000s. For Hurricane Katrina, this amounted to 1800 deaths in New Orleans, while as a result Cyclone Sidr the deaths were about 3,100.
In both events the majority of the people were left homeless
In both events, getting relief to people was rather slow. In the case of Katrina, it was because the authorities took a long while to get moving. While in Sidr, blocked roads and the fact that supplies had to be brought in, slowed the aid up.
In both places, there was lot of work to be done later to make sure the next cyclic storm did less damage. In New Orleans this meant ensuring the levees were mended properly. In Bangladesh, they needed more storm shelters.
Both lost water and power supplies during the storm.
Both lost farmland to inundation from salt water
Bangladesh had a well organised evacuation plan that involved the use of mobile phones, speed boats, motorbikes and megaphone. This meant that many lives were saved. In New Orleans, they left the warnings far too late and did not organise the evacuation of people without transport. This meant that many were left marooned in flooded homes.
Because Bangladesh is an NIC, the damage that was done was not so costly as it was in New Orleans, USA which is an HIC.
Most of the damage after Katrina was caused by the storm surges, while much more damage from Sidr resulted from the rain and the wind.
New Orleans suffered much more from industrial pollution as the oil fields and refineries were damaged both by the winds and the surge.
Most people in Bangladesh returned home quite quickly and started rebuilding their lives. But 4 years on, many people have not returned to New Orleans.
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