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This inquiry explores the complex factors contributing to flooding in New Orleans, a city lying below sea level and surrounded by water bodies. With one of the world's most extensive levee systems, the city's unique geographic attributes pose significant risks. We investigate the structure of levees, the impact of ground subsidence caused by water removal, and the vulnerabilities of flood walls, particularly during storm surges. Through geographic data analysis, we seek solutions to enhance flood protection and learn from other nations facing similar challenges.
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Geographic Inquiry: Why did New Orleans Flood?
Exploring Geographic Data • What is a levee? earthen structure made of clay 10 times wider base than height • New Orleans has one of the most extensive levee systems in the world
Levees along Mississippi A levee along the Mississippi River
New Orleans Lies in a Bowl • New Orleans lies an average of 6 ft below sea level • Metropolitan area surrounded by Lake Pontchartrain, the Mississippi River, and swampland extending to the Gulf of Mexico less than 100 miles South • System of canals, pumps, elevated levees, and floodwalls form bowl protecting city
Why City Is Sinking • “Every drop of water that comes into New Orleans has to be pumped out” • Large canals collect ground water so the water can be pumped out of the city • But removing ground water causes city to “settle” or sink even further • Places where canals connect to the river, lake are weak spots in the levee system
Analyzing Geographic Info • Levees did not fail; some flood walls failed. • Locations of flood walls that failed: 17th Street Canal London Avenue Canal Industrial Avenue Canal Can we find these areas on a map?
Causes of Flooding • Inadequate design of flood walls: • rising water in canals toppled walls because footings not sunk deep enough in ground; • when earth became wet, pressure from water in canal caused wall to lean over • Inadequate maintenance • Wetland loss in the Mississippi Delta meant less protection from storm surge
Acting on What Was Learned • What could be done to prevent this from happening again? • What have other nations with similarly endangered cities done to prevent catastrophic storm surges?
