Why Was Hurricane Katrina So Destructive?
The geographical theme I have cosen to write about is Hurricanes as this is a topic we have been studying in class and has intrested me to learn more about this natural hazard. The geographical location I will be studying is New Orleans and Florida where hurricane Katrina was most destructive. Katrina struck the state of Louisianna at 10am on the 29th of August 2005.
What I have learned in Class
In class I have learned how the National Hurricane centre detects earthquakes using many different methods from aeroplanes to balloons that fly into the atmosphere and record the weather.
This diagram shows where hurricanes form and what they are called in different areas of the world. Hurricanes are like giant engines that use warm moist air as fuel. That is why they form only over warm ocean waters near the equator. The warm moist air over the ocean rises upward from near the surface. As this air moves up and away from the surface, there is less air left near the surface. Another way to say the same thing is that the warm air rises, causing an area of lower air pressure below. Air from surrounding areas with higher air pressure pushes in to the low pressure area. Then that "new" air becomes warm and moist and rises, too. As the warm air continues to rise, the surrounding air swirls in to take its place. As the warmed, moist air rises and cools off, the water in the air forms clouds. The whole system of clouds and wind spins and grows, fed by the ocean's heat and water evaporating from the surface. Hurricane Katrina began as a very low pressure weather system, which strengthened to become a tropical storm and eventually a hurricane as it moved west and neared the Florida coast on the evening of 25 August. After crossing southern Florida - where it left some 100,000 homes without power - it strengthened further before veering inland towards Louisiana, eventually making landfall at Grand Isle, approximately 90km south of New Orleans. This is a map showing the path of the hurricane going through Florida then heading straight for New Orleans. This diagram shows that when there is green dots the hurricane was only a tropical storm, the yellow dots shows when the hurricane was a category 3, the white dots represent when the hurricane was category 4 and the red dots represent a category five.
Hurricane force winds were recorded along a 200km stretch of coastline, with scenes of similar destruction and flooding in Louisiana, Mississippi and Alabama. Storm surges from the sea caused flooding several kilometres inland in some places such as New Orleans. Hurricane Katrina tracked over the Gulf of Mexico and hit New Orleans, a coastal city with huge areas below sea-level which were protected by defence walls, called levees. The hurricane's storm surge, combined with huge waves generated by the wind, pushed up water levels around the city.The levees were overwhelmed by the extra water, with many collapsing completely. This allowed water to flood into New Orleans, and up to 80% of the city was flooded to depths of up to six metres. Damage Caused by Hurricane Katrina
The damage caused by the hurricane was immense. On Monday August 29 area affiliates of local television station WDSU reported New Orleans was experiencing widespread flooding due to several Army Corps-built levee breaches, and that there were several instances of catastrophic damage in residential and business areas. Entire neighborhoods on the south shore of Lake Pontchartrain causeway were flooded.
Most of the major roads traveling into and out of the city were damaged, such as the bridges in the photo above. The only route out of the city was west on the Crescent City Connection as the I-10 Twin Span Bridge traveling east towards Slidell, was heavily damaged. It suffered the worst of the bridge failures, with 473 spans separating from their supports and 64 spans dropping entirely into the lake.The...
Encylopedia Britannica 2012
The World Book Encyclopedia 2013
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