NEW ORLEANS – The ongoing Hurricane and Storm Damage Risk Reduction System (HSDRRS) ties into existing Mississippi River Levees for both the east and west banks. Due to updated technical analyses and a more sophisticated examination of the Mississippi River flows the Corps of Engineers will make additional improvements to the Mississippi River Levees co-located with the Hurricane and Storm Damage Risk Reduction System.
The Mississippi River Levee (MRL) system was designed to protect against a riverine event, not a hurricane storm surge. In order to provide 100-year risk reduction from storm surge, the Corps is using adaptive management to incorporate new modeling capabilities and analysis to upsize the MRL.
“We discovered new technical information regarding the Mississippi River average flows for hurricane season,” said Col. Alvin B. Lee, New Orleans District commander. “Previous modeling assumed one river flow. The Mississippi River flow during Katrina was lower than the average river flow during the peak of hurricane season. Based on this information, the Corps used adaptive management to modify new technical analyses and information to account for varying flows in the Mississippi River as they relate to the modeled storm surges.”
The initial models were good tools for the system’s initial evaluation but could not have accomplished the more complex analysis, which examined combined river discharge and storm surge, considerably advancing the capability of analysis. Remodeling using the newly available methods required considerable effort.
Fourteen miles of Mississippi River Levee within the West Bank & Vicinity (WBV) system, at the lower end of the Belle Chasse polder, require an increase in existing elevations up to 3.5 feet at river mile 70, diminishing to no increase needed at river mile 84.
Three miles of Mississippi River Levee within the Lake Pontchartrain & Vicinity (LPV) system at the lower end of the St. Bernard polder require an increase in existing elevations up to 0.5 feet. at river mile 81, diminishing to no increase needed at river mile 84.
The Corps will perform the necessary engineering and environmental analyses in the coming months to determine required designs.
The Corps remains committed to deliver the Hurricane and Storm Damage Risk Reduction System to Greater New Orleans by June 2011. Part of that challenge and responsibility is using adaptive management to incorporate new technical analyses and information into the work requirements
Release no. 09-038