Protecting St. Bernard Parish, New Orleans: Revision of the coastal defence zone

This document is the final report of a Master thesis research. The research was executed as cooperation between Delft University of Technology, ARCADIS and ComCoast as part of The Road and Hydraulic Engineering Institute of the Directorate-General of Public Works and Water management (RWS DWW). In this report, the hurricane defence system of St. Bernard Parish is analysed and ComCoast like solutions are sought in order to make the area safe for a new Katrina. This Master Thesis analyses the failure of the St. Bernard Parish coastal defence system. Subsequently, it develops spatial integrated solutions for the coastal defence zone, using the coastal defensive strategies, which follow from the ComCoast-concept. Additionally, the effects of wetlands on a storm surge are investigated by means of an analytical analysis and a numerical model. It was concluded that catastrophic failure of the coastal defence system could have been prevented if the primary dike was not partly constructed of poorly non cohesive materials. Some basic constructional calculations and a quick study on environmental impacts made clear that the ComCoast alternatives; Overtopping resistant dike and Foreshore recharge, offer the most suitable solutions for the St. Bernard Parish area. The study on the effect of wetlands on a storm surge showed that it can both lead to a decrease, as an increase of the eventual storm surge height at the dike. The analytical and numerical approach has increased the understanding of the hydraulic behaviour of the system