City of New Orleans: Floodplain analysis after Hurricane Katrina

Following Hurricane Katrina, Ramboll conducted environmental assessments of damaged properties, structures and infrastructure in New Orleans, Louisiana, USA to determine storm-related impacts and identify alternatives to rebuilding in the floodplain, including mitigating measures for future floodplain protection. The process included public engagement and input at each stage of the analysis.

For example, the alternatives analysis for the City of New Orleans included establishing inventories of available lands outside of the 100-year floodplain; estimating the costs to relocate homes and the related costs of new or upgraded infrastructure; determining potential impacts to several other resources such as sensitive species and wetlands; and considering the overall employment and social service impacts to residents.

Ramboll’s assessments revealed that relocating the entire affected population to homes outside of the 100-year floodplain was not only infeasible, but no more protective of the environment than implementing key floodplain mitigation measures in the affected regions.

Ramboll’s ongoing efforts in this project, which have won praise from the US Department of Housing and Urban Development (HUD), are now used as a model for floodplain analyses required under the National Environmental Protection Act (NEPA) to qualify for federal disaster recovery funds.