Why Was Hurricane Katrina So Destructive

Why Was Hurricane Katrina So Destructive?

Introduction
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 24-mile (39 km) long Lake Pontchartrain causeway escaped unscathed but was only carrying emergency traffic. Louis Armstrong New Orleans International Airport was closed before the storm but reported no flooding in airplane movement areas or inside of the building itself. By August 30, it was reopened to humanitarian and rescue operations. Commercial cargo flights resumed on September 10, and commercial passenger service resumed on September 13.
Final reports indicate that the official death toll, according to the Louisiana Department of Health, was 1,464 people.The first deaths were reported shortly before midnight on August 28, 2005, as three nursing home patients died during an evacuation to Baton Rouge.
On September 4, Mayor Nagin speculated that the death toll could rise as high as ten thousand after the clean-up was completed.Some survivors and evacuees reported seeing bodies lying in city streets and floating in still-flooded sections, especially in the east of the city. The advanced state of decomposition of many corpses, some of which were left in the water or sun for days before being collected, hindered efforts by coroners to identify many of the dead.
There were six deaths confirmed at the Superdome. Four of these were from natural causes, one was the result of a drug overdose, and one was a suicide. At the Convention Center, four bodies were recovered. One of these four is believed to be the result of a homicide. Body collection throughout the city began on approximately September 9. Prior to that date, the locations of corpses were recorded, but most were not retrieved. Later studies determined that most of New Orleans ' Katrina dead were elderly persons living near levee breaches in the 9th Ward and Lakeview.

Why Was Katrina Such a Devestating Hurricane Katrina was a category 5 hurricane (winds up to 175 miles per hour) as it moved across the Gulf of Mexico . When it hit land in Louisiana, it had dropped to a category 3 with winds up to 125 mph. It was not the strongest hurricane to ever make landfall, but it was extremely destructive. It was so destructive primarily because levees around New Orleans, Louisiana failed. Levees are water barriers built to prevent flooding (parts of New Orleans have an elevation that is lower than sea level). When the levees failed, huge areas of the cities flooded. Very heavy winds also contributed to the damage, but flooding was the most destructive aspect of the hurricane.
A June 2007 report released by the Aerican Society of Civil Engineers states that the failures of the locally built and federally funded levees in New Orleans were found to be primarily the result of system design flaws. The US Army Corps of Engineers who by federal mandate is responsible for the conception, design and construction of the region 's flood-control system failed to pay sufficient attention to public safety.
According to modeling and field observations by a team from Louisiana State University, the Mississippi River Gulf Outlet, a 200-meter-wide (660-foot-wide) canal designed to provide a shortcut from New Orleans to the Gulf of Mexico, helped provide a funnel for the storm surge, making it 20% higher and 100%-200% faster as it crashed into the city. St. Bernard Parish, one of the more devastated areas, lies just south of the MRGO. The Corps of Engineers disputes this causality and maintains Katrina would have overwhelmed the levees with or without the contributing effect of the MRGO.The water flowing west from the storm surge was perpendicular to MRGO, and thus the canal had a negligible effect.

This diagram shows the position of the levees that were breached during Katrina and the pumping stations position in thr aftermath of the Hurricane. Also it shows the areas near the breaches that were below sea level and were prone to flooding.

Bibliography news.bbc.co.uk/2/shared/spl/hi/americas/05/katrina/html/ www.livescience.com/22522-hurricane-katrina-facts.html www.ncdc.noaa.gov/extremeevents/specialreports/Hurricane-Katrina.pdf Encylopedia Britannica 2012
The World Book Encyclopedia 2013