A combination of historical and geological factors combined with inadequate design of levees and floodwalls resulted in a series of levee overtoppings and catastrophic levee failures in the New Orleans area during the passage of Hurricane Katrina on August 29, 2005.  Early in the morning of August 29, levees along the Mississippi River – Gulf Outlet and Intracoastal Waterway were overtopped by the storm surge generated by Katrina resulting in the flooding of eastern New Orleans and St. Bernard Parish.  Later in the morning storm surge entering New Orleans’ Inner Harbor Navigational Canal overtopped levees and floodwalls on both sides of the canal, eventually resulting in the catastrophic failure of the floodwalls and the destruction of the Lower 9^th Ward.  Three drainage canals in New Orleans, originally constructed in the mid-1800s to drain rainwater from the city into Lake Ponchartrain to north, then became subject to storm surge entering from the Lake.  The excess pressure of the surge combined with the weak geological material underlying the levees and floodwalls resulted in two levee breaches on the London Avenue Canal and one on the 17^th St. Canal by mid-morning on August 29.  These breaches resulted in flooding of about 80% of the city of New Orleans.  The failures of levees on these drainage canals did not result from overtopping the floodwall system, but apparently from weaknesses in the design of the system that failed to adequately account for the underlying geologic conditions.