Cyclones

Cyclones: Finally a natural disaster which Bangladesh is not only familiar with but also somewhat PREPARED FOR. In case you missed the last episodes, Bangladesh should not be on your top ten places to live list. It turns out that Bangladesh does not have any of its own satellites and it relies on the NOAA and NASA satellites which send data remotely to the Bangladesh Space Research and Remote Sensing Organization, which is part of the Ministry of Defense. Apparently SPARRSO has a detailed “storm prevention” strategy (I think this is simply a poor choice of semantics on their part but it makes for rather amusing brain fodder to imagine a group of wizards at the ministry of defense combining their power to stave off the forces of nature). All joking aside, they have a volunteer force of approximately 32,000 people who are trained to warn and evacuate citizens especially in lower coastal areas and a network of 2,500 cyclone shelters. Petenga and Chittagong have built sturdy concrete levees to protect that part of the coast. After reading about how cyclones affect Bangladesh, I can see why they do not spend much time or money (comparatively) on earthquake or even subsidence mitigation. The Bhola Cyclone in 1970 killed 500,000 people (and that statistic is likely to be conservative). Over one million cattle were killed, 20,000 fishing vessels, 400,000 houses and 3,500 educational institutions were also destroyed. The wind during the Bhola Cyclone reached a maximum of 222km/hr and the maximum sure was over 10 meters. Bangladesh suffers primarily from tropical cyclones. They can last up to 24hrs and they produce  a huge amount of heart and moisture. They knock out power and contaminate what few potable water supplies Bangladesh has. In a country as heavily populated as Bangladesh, a power blackout could be devastating in itself as it would put hospital equipment out of commission and probably slow down the warning and guiding systems necessary to reach as many people as possible in a disaster.  http://en.wikipedia.org/wiki/List_of_Bangladesh_tropical_cyclones

In April of 1991 another massive cyclone hit the coast of Bangladesh. It is now known as the Bangladesh Cyclone. It killed approximately 15,000 people which is a lower death toll than the one recorded in the Bhola Cyclone but I believe this was due to the country’s mitigation techniques having improved since the 70’s. Still, many died because they refused to evacuate, believe the intensity of the storm to be less than forecasted. The Max wind speed was 260km/hr which was measured for a minute at a time. This is the timing scale Bangladesh uses to measure wind speed as opposed to being measured over a 3 minute period which is what most countries use.  What is surprising about cyclone death tolls in the area are the number of people who die from drowning. Most of the deaths in the Bangladesh cyclone of 1991 were drowning victims. This boggles my mind because I can see disease and water contamination as well as insufficient shelter being the cause of so many deaths but for some reason it is too surreal for me to comprehend. http://en.wikipedia.org/wiki/1991_Bangladesh_cyclone The initial dome of water which makes landfall is called the storm surge and it is caused by a combination of the hurricane’s winds and ocean surface which form not so much a tidal wave as a mountain of water to rise and then collapse on shore.  90% of the deaths in cyclone in Bangladesh are caused by the storm surge. The storm surges in Bangladesh are particularly deadly because the water nearest the coast is relatively shallow which means the surge does not have the depth or breadth of ocean space to disperse and loose energy. These surges can travel inland as far as 25miles and there is no method of prevention so the only mitigation option is to evacuate to a higher elevation.

Interestingly, although Bangladesh does utilize the hurricane rating system with the intensity scale of 1-5, it also rates its tropical storms on a scale of 10 to measure destruction.

Along with the initial storm surge there is of course torrential rainfall during a hurricane and this rain causes flooding and landslides which also claim property and lives.

In 2008 Tropical Cyclone Nargis hit Mayanmar, Bangladesh, India and Sri Lanka with winds reaching 215 km/hr (on the one minute time scale mentioned above). The total death toll was approximately 138,000 people. Only 3,500 of those were in Bangladesh. It was one of the most destructive cyclones in the history of the area, causing approximately 10 billion dollars in damage throughout all 4 countries. Yet, it seems as though Bangladesh is doing quite well for itself in regards to the road to Cyclone disaster prevention.

http://dhaka.usembassy.gov/acs_cyclones.html

http://en.wikipedia.org/wiki/Cyclone_Nargis