Tropical Cyclones and Deaths Due to Their Existence

Tropical Cyclones and Deaths Due to Their Existence
Tropical cyclones are given different names depending on which part of the world they occur, for example in Asia and Arabia they are called ?Cyclones?, however in Australia they are called ?Willy Willies?. For consistency within this essay, they will be referred to as hurricanes. It is important to clarify the frequency and spatial distribution of hurricanes. Certain conditions are required for a hurricane to develop. There needs to be a disturbance in the lower surface atmospheric circulation, a large coriolis force, wind levels at all levels in the same direction and a rapid outflow of air from the upper troposphere replaced by an inflow at ground level. Also, excess heat needs to be transported away by the troposphere and the air needs to be unstable with high humidity. Another important condition is that the temperature of oceans needs to be above 26?c in water to a depth of 70m. These high temperatures are generated around the tropics. Hurricanes only develop between 5? north and south of the equator.
Hurricanes develop over large warm ocean seas because of the large amount of energy and the humidity. Once a hurricane hits the coast it immediately starts to loose energy and therefore begins to break up. Therefore coastal areas are more at risk from hurricanes. Analysis of the countries along the equator and tropics area shows that although there are MEDC?s such as usa and Australia, the majority of countries are LEDC?s such as Bangladesh, Malaysia, Nigeria and Somalia. This immediately shows that even if MEDC?s and LEDC?s had the same provisions, as there are more LEDC?s in this zone, the likelihood they will be hit by a hurricane is higher and therefore there is likely be more deaths in LEDC?s. Another factor that needs to be considered is the pattern of settlement in LEDC?s. During colonial times, large urban areas in LEDC?s tended to be in coastal regions, for example Lagos in Nigeria. This was to increase accessibility for trade and movement. As these urban areas were given a head start by means of infrastructure from before they gained their independence, they have tended to be the urban settlements which have grown the most. Clearly this is a problem as these are the areas in LEDC?s in the tropics which are most likely to be affected by hurricanes. The density of the population in these regions increases vulnerability. If the area is an ledc city, then it is likely to have large numbers of migrants from rural areas. Due to age and sex selective migration and natural increase these urban areas will have a rapidly growing population. Also if there is rural-urban migration, it is likely that couples from rural areas will still be having a large number of children, but due to better health care a larger proportion of these will be surviving and thus increasing the urban population. Population density in LEDC?s is relatively higher, thus even if the affected area is not urban it will have a high population density. Therefore there will be more people affected and a higher chance of these people affected resulting in death. Figure1: Countries affected by hurricanes and their populations and population densities Country Actual Population (1998) Population Density (person/km²) Nigeria 106,409,000 115.2 India 982,223,000 298.8 Bangladesh 124,774,000 107.5 usa 274,028,000 27.9 Australia 18,520,000 2.4 As figure 1 shows the population density in LEDC?s is much higher than that of MEDC?s and this is encompassing both rural and urban areas. If for example, a hurricane was to hit 5km into the inland of Bangladesh, it would affect more people (due to the higher population density) than if it hit the same amount of area in Australia as there would be fewer people affected. Hurricane Andrew was the third largest hurricane to effect mainland usa. August 24th 1992 it crossed Florida and the Gulf of Mexico, two days later it reached Louisiana. The storm killed 3 people in the Bahamas, 15 people in Florida and 8 people in Louisiana, adding up to a total of 26 people directly killed by the hazard. Indirectly 39 people were killed, this was due to electrocutions and clean up accidents. The hurricane was noticed 7 days in advance. The hurricane in Bangladesh just sixteen months earlier on April 30th 1991 killed approximately 140,000. In MEDC?s the damage created by a hurricane is usually measured by the economic losses rather than the deaths. This shows a capitalistic response, however it does show that the population is sufficiently protected from this hazard as loss of life is a decreasing issue. The hurricane in Bangladesh was only noticed four days in advance, this could have some effect on the loss of lives, however this must not be the only reason why there is such a huge difference. In Bangladesh an official evacuation warning was not issued until just fourteen hours before the hurricane hit the shore. This is in spite of regular updates on the radio of what was to be expected, including information on the storm surge. It seems that nothing was done with the available information until it was too late. Hurricane Andrew on the other hand, was predicted in advance, and people were given warnings in advance. Over one million people left Miami in time to avoid the hazard. Newsreaders also gave people advice on how to stay safe during the hurricane, and told them how they should move to shelters and store food and water. If evacuation in Bangladesh had have been made earlier it is likely that a reduction in the loss of life would have been possible. One important factor which needs to be considered is the public perception of evacuation warnings. If warnings are given out regularly that there is going to be a hurricane, people become complacent and think that it is likely to be another false alarm. However, if prediction is accurate then warnings can be made and most people will adhere to them. It is likely that with a larger capital in MEDC?s equipment to predict hazards such as hurricanes is going to be more up to date and accurate. In LEDC?s it is likely that the equipment will not be as modern and therefore may not be as accurate and therefore will increase sceptical attitudes towards warnings. A proactive response was taken towards hurricanes in LEDC?s. For example, hurricane shelters had been erected (this was due to the devastation of the 1970 hurricane) also embankments along the coast were built and teams of volunteers organised. Unlike the usa which was more reactive in its response to the hurricane. However, more people were killed in Bangladesh. This could be due to the media. In the usa there were newsreaders giving vital information and educating the citizens on what they should do, unlike in Bangladesh, where there is not such a large media network. Florida is a large tourist area, and many people have holiday homes along the coast. These are second homes were unable to be prepared for the hurricane and therefore incurred damage. The property in LEDC?s is likely to be of poorer quality (especially for the poorest citizens) and therefore would not have protected them from the rapid wind speeds. The poorest people in LEDC?s live in marginal land, for example flood plains, if storm surges occur due to the hurricane it is going to be the spontaneous settlements of these people which are going to be destroyed and washed away, along with the people themselves. Marginal land can include steep slopes. If there is high rainfall then there will be a reduction in friction causing mass movements which could cause deaths from the rapidly moving material. This could be why in LEDC?s there are a much larger number of deaths. One shocking example of a spontaneous settlement is Smokey Mountain, in the Philippines; it is in fact a rubbish dump which houses mostly bridgeheaders who have undergone rural-urban migration. This would become very dangerous with high rainfall, it is likely to cause many chemical reactions, and mass movement due to the reduction of friction. Hurricane Mitch struck Central America in October 1998. It was the second most destructive Atlantic hurricane. It reached category five in the Saffir-Simpson scale in the Caribbean Sea on October 26th. The reason Mitch caused such destruction was due to the huge amounts of rainfall which fell. This was influenced by the slow speed that the hurricane moved as well as the orthographic effect of the Central American mountains. The duration and intensities of the rainfall were huge. On 29th October it rained continuously for sixty-one hours. On October 31st a total of 787mm of rain was recorded. During this time there were three distinct periods of very intense rainfall. This caused widespread flooding, rivers changing their courses and landslides. This was increased by the antecedent conditions, as the area was at the end of its wet season, and therefore had experienced high rainfall prior to the hurricane. Agriculture was ruined due to soil erosion and floods ruined many crops as well as killing many people. The crater lake of Casitas volcano burst sending an avalanche of mud which buried 80km² and killed 2000 people. This hurricane caused in total eleven thousand deaths. This is a huge number, and does not take into account the number of missing people. We cannot be sure that if the same hazard had struck an medc there would be less devastation. The housing in LEDC?s if in a rural area, quite basic, and would not withstand the winds of a hurricane. The foundations would not hold the house down. If it were in an urban area, the richer people would have housing similar to that in MEDC?s however the poorer people would be at a great risk. After the hurricane, in LEDC?s not only would large areas of cash crops have been destroyed, but it is likely that there could be an increase in water-born diseases such as cholera, typhoid and dysentery. This could increase the death toll. MEDC?s have the money to invest in methods to modify the event. For example hazard resistant buildings. In Galveston, Texas, following the storm surge of September 1900 where six thousand people were killed, the whole city was elevated by three and a half metres. It is also now protected by a huge sea wall. The scheme took seven years to complete and was very expensive. Schemes such as this could not be done by LEDC?s. Therefore it does seem likely that tropical cyclones cause disproportionately fewer deaths in LEDC?s than in MEDC?s. This could be due to many factors as discussed, including population densities, the higher number of LEDC?s in the vulnerable area, the high cost of modifying the vulnerability and modifying the event.

Tropical Cyclones and Deaths Due to Their Existence 7.9 of 10 on the basis of 1700 Review.