M Long A2.Katrina_1

M Long A2.Katrina_1 - Assignment 2 Hurricane Katrina 1 The...

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Assignment 2. Hurricane Katrina. 1. The Mississippi River built Southeast Louisiana over approximately 7,000 years. (4) 2. Several thousand years ago the sea level was rising because glaciers left over from the ice age were still melting (4). 3. As glaciers melted and the sea level rose, a small bay took shape that would eventually become Lake Pontchartrain. The Mississippi River changed course towards present-day New Orleans and the St. Bernard Delta continued to grow the Mississippi river dumped sediment, eventually connecting with Pine Island and closing off Pontchartrain Bay from the Gulf of Mexico to form Lake Pontchartrain (4). 4. Most maps today depict the Louisiana coastline as it was in 1930. This is deceptive because it does not reflect the changes resulting from levees and jetties, canals & channels, land subsidence, saltwater intrusion, invasive species and sea level rise that have cut away at the state’s coastline (4). 5. Louisiana loses approximately 24 square miles of wetlands per year (4). 6. Six factors that cause the wetlands to disappear and the coastline to recede are levees & jetties, 7. Land subsidence causes land to sink as s water and gases are squeezed out by the soils own weight and new sediment fails to replenish the loss. Land sinks faster near the mouth where sediment escapes into deep water, preventing marshes from rebuilding (4). 8. What role do canals have in destroying the wetlands and marshes? Thousands of miles of web-like pipeline and navigation canals are directly responsible for destroying 10-30% of the marshes. They also indirectly result in additional land loss by cutting off marshes from natural water flow, opening them up to salt water intrusion and erosion by boat traffic (4). 9. Salt water intrusion plays a role in destroying wetlands and marches because salt water from the gulf moves inland through canals and waterways killing freshwater plants that can’t live in the salt. As the plants die, the soil their roots hold together is eroded away (4). 10. Levees were constructed beginning with the founding of New Orleans 1718 to keep the Mississippi River from overtopping its banks and flooding the area as it did nearly every Spring. The levees also created stable channels for shipping (4). 11. The levees cut off sediment-rich flood waters that built the land on which the city sits and
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This note was uploaded on 07/24/2010 for the course SMT 312 taught by Professor Staff during the Winter '10 term at CSU Dominguez Hills.

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M Long A2.Katrina_1 - Assignment 2 Hurricane Katrina 1 The...

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