USA HISTORY

Detailed explanation-1: -All concurred that the primary cause of the flooding was inadequate design and construction by the Army Corps of Engineers. In April 2007, the American Society of Civil Engineers termed the flooding of New Orleans as “the worst engineering catastrophe in US History."

Detailed explanation-2: -During and after Hurricane Katrina, many of those levees and floodwalls were overtopped and several were breached, allowing billions of gallons of water from the Gulf of Mexico, Lake Borgne, and Lake Pontchartrain to flow into New Orleans and flood major portions of the city.

Detailed explanation-3: -Rather than a few breaches through the floodwalls in the city caused largely by overtopping, we found literally dozens of breaches throughout the many miles of levee system. A number of different failure mechanisms were observed, including scour erosion caused by overtopping, seepage, soil failure, and piping.

Detailed explanation-4: -After it made landfall in Louisiana on August 29, Hurricane Katrina produced widespread flooding in southeastern Louisiana because the levee system that held back the waters of Lake Pontchartrain and Lake Borgne was completely overwhelmed by 10 inches of rain and Katrina’s storm surge.

Detailed explanation-5: -Breaches in the system of levees and floodwalls left 80 percent of the city underwater. Breaches in the system of levees and floodwalls left 80 percent of the city underwater. By the time Hurricane Katrina made landfall near Buras, Louisiana early on the morning of August 29, 2005, the flooding had already begun.