Geographic Inquiry:Geographic Inquiry:

Why did New Orleans Flood?Why did New Orleans Flood?

Breech in LeveeBreech in Levee

Exploring Geographic DataExploring Geographic Data

What is a levee?What is a levee?earthen structure made of clayearthen structure made of clay

10 times wider base than height10 times wider base than height

New Orleans has one of the most New Orleans has one of the most extensive levee systems in the worldextensive levee systems in the world

Levees along MississippiLevees along Mississippi

A levee along the Mississippi River

New Orleans Lies in a BowlNew Orleans Lies in a Bowl

New Orleans lies an average of 6 ft New Orleans lies an average of 6 ft below sea levelbelow sea level

Metropolitan area surrounded by Lake Metropolitan area surrounded by Lake Pontchartrain, the Mississippi River, and Pontchartrain, the Mississippi River, and swampland extending to the Gulf of swampland extending to the Gulf of Mexico less than 100 miles SouthMexico less than 100 miles South

System of canals, pumps, elevated System of canals, pumps, elevated levees, and floodwalls form bowl levees, and floodwalls form bowl protecting cityprotecting city

Why City Is SinkingWhy City Is Sinking

““Every drop of water that comes into Every drop of water that comes into New Orleans has to be pumped out”New Orleans has to be pumped out”

Large canals collect ground water so the Large canals collect ground water so the water can be pumped out of the city water can be pumped out of the city

But removing ground water causes city But removing ground water causes city to “settle” or sink even furtherto “settle” or sink even further

Places where canals connect to the Places where canals connect to the river, lake are weak spots in the levee river, lake are weak spots in the levee systemsystem

Analyzing Geographic InfoAnalyzing Geographic Info

Levees did not fail; some flood walls failed.Levees did not fail; some flood walls failed.

Locations of flood walls that failed:Locations of flood walls that failed:1717thth Street Canal Street CanalLondon Avenue CanalLondon Avenue CanalIndustrial Avenue CanalIndustrial Avenue Canal

Can we find these areas on a map?Can we find these areas on a map?

Causes of FloodingCauses of Flooding

Inadequate design of flood walls:Inadequate design of flood walls: rising water in canals toppled walls rising water in canals toppled walls

because footings not sunk deep because footings not sunk deep enough in ground; enough in ground;

when earth became wet, pressure from when earth became wet, pressure from water in canal caused wall to lean over water in canal caused wall to lean over

Inadequate maintenance Inadequate maintenance Wetland loss in the Mississippi Delta Wetland loss in the Mississippi Delta

meant less protection from storm surgemeant less protection from storm surge

Acting on What Was LearnedActing on What Was Learned

What could be done to prevent this What could be done to prevent this from happening again?from happening again?

What have other nations with similarly What have other nations with similarly endangered cities done to prevent endangered cities done to prevent catastrophic storm surges?catastrophic storm surges?