Geographic Inquiry:

1. Geographic Inquiry: Why did New Orleans Flood?

4. Breech in Levee

5. 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

6. Levees along Mississippi A levee along the Mississippi River

7. 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

9. 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

11. 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?

16. 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

17. 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?