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During Hurricane Katrina the water surge level became very high and dykes and flood walls along the IHNC were breached in several places. “Hurricane Gustav last September showed once again how badly this surge barrier is needed,” says project leader Mathijs van Ledden. “The water came right up to the top of this canal’s flood walls, which are intended to protect a couple of hundred thousand people.” The risk of flooding in the central part of the city will be substantially smaller after the surge barrier has been completed.

This surge barrier is a technical challenge from a number of different points of view. The design water level for it is comparable to the once in 10,000 years water level along the Dutch coast (about 6 metres above sea level). The design height of the barrier has been optimized by taking into account the storage capacity behind it. Finally, the local subsoil is very weak. This resulted in the selection of a concrete flood wall instead of a conventional dyke. In addition to the surge barrier, the heights of the dykes on both sides of the flood wall also have to be raised substantially. This makes the system complete.

Royal Haskoning has had an office in New Orleans since 2006. Together with American partners, in 2007 this office was awarded a major project by the Department of Water Resources relating to flood protection in and around Sacramento, California. Over the last year Royal Haskoning has also executed a number of flood protection projects for private and public sector clients in the New Orleans area.