Background
It's no known secret about what happened during Hurricane Katrina. Although some may not fully understand what occurred prior to the massive storm hitting the southern coast of the United States.
According to history.com, a tropical depression formed over the Bahamas on August 23, 2005, thus allowing meteorologist to notify people along the Gulf Coast states that a major storm was coming. A few days later, a mandatory evacuation of the city was issued on August 28th, 2005 in response to the Occurrence of the Hurricane. The hurricane was dubbed a category 3 when it hit the coast, although it did reach a category 5 before touching land.
(Image above: Hurricane Katrina)
Why It Hit Hard
Looking at New Orleans specifically, it's no surprise that this city was the most at risk. The average elevation of the city of New Orleans lies below sea level, putting it at greater risk for damage and flooding. Although the Army Corps built a newer system of levees and seawalls along the Mississippi in the 20th century, the ones built to hold back Lack Pontchartrain, Lake Borgne and the waterlogged swamps and marshes to the city's east and west were less reliable. This was imperative to the situation, because although it would seem as if the water coming from the ocean was the cause of the massive destruction, it was actually the levees breaching in certain areas that caused the massive flooding.
What Are Levees
The levees in New Orleans are the things that surround the lakes. Most of the lakes in New Orleans were man made in order to help to divide up the different colonies, or sections per-say. However, the way they were enforced into the ground in order to prevent flooding was not reliable.
The image below shows exactly what the levee is and how its structure is set up.
The images below shows an illustration of how exactly the levees broke. The first image to the left, shows how the water is pressing up against one side of the levee. Image 2, center image, is showing how the water started to break between the land and the levee thus pushing it back. Due to little support from the other other end, the third image depicts how the levee was easily pushed out of place, thus compromising the structure and allowing the water to invade the other side.
Image 1 Image 2 Image 3
(Image above: Lake front and sea wall of Lake Pontchartrain)
Definitions:
Tropical Depression: occurs when a low pressure area is accompanied by thunderstorms that produced circular wind flow with maximum sustained winds below 25 and 35 mph. This then upgraded to a tropical storm, followed by a Hurricane.
Reference links:
Reference 2Reference 3 along with levee images
(Done by Kimberly Carson)
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