In 2005 hurricane Katrina hit New Orleans and Louisiana resulting in lives being taken and billions dollars of damage. After this event the US Army Corps of Engineers (USACE) had two key challenges:
- to reduce the risk to flooding significantly
- to get better information about the potential scenarios and an estimation of expected water levels from hurricanes, allowing better preparation in time.
Flood management systemRoyal HaskoningDHV had a leading role in the re-design of the flood defence system for New Orleans with the resilience to minimise damage from a 100-year storm event. Expert environmental engineering improved practical defence structures, while cutting-edge technology created information management systems to integrate operational processes. After detailed analysis Royal HaskoningDHV provided conceptual designs for structures to support and strengthen the levees, which will now be resilient against storm events more severe than the 100-year standard. Another aspect of the new flood defences was to strengthen the eroded marshlands of the Louisiana coasts which act as a natural barrier against the sea. Advanced hydraulic modelling confirmed the possibility of diverting part of the Mississippi river into the marshland area, making it more resilient to flooding. By lowering the barrier and making use of the natural systems for flood protection a cost saving of hundreds of millions of US Dollars was achieved plus a more robust flood protection system.
Levee Information Management systemRoyal HaskoningDHV also helped to improve the operational processes surrounding the use of the flood defence structures. Five days before a storm many decisions have to be made regarding evacuation of residents and deployment of emergency services. Over 300 flood gates need to be opened or closed at appropriate times. In some cases closing floodgates may restrict access to streets or transport links, so it is vital to make informed decisions. Royal HaskoningDHV helped to develop a Levee Information Management System that integrates all the information the decision makers need, as well as providing detailed technical information for each section of the levee, all to support asset management.
Hurricane Surge AtlasAnother innovative operational tool which was introduced is a Hurricane Surge Atlas. The Atlas makes all data accessible electronically, online and even paper copies for use in an emergency such as a power cut based on modelled potential outcomes of 300 different types of hurricane (different types of speed, direction, air pressure and hurricane size) using supercomputers to handle the high volume of data. By using the hurricane characteristics to define potential scenarios time was won compared to use of measured water levels which gives an earlier indication of what might happen resulting in more time for decision taking and preparation.
See also: Paper: A digital Hurricane Surge Atlas for New Orleans.