Hurricane design conditions for hotel infrastructure at Saint Barth

The Challenge

In September 2017 the category 5 hurricane Irma passed over the Antilles in the Caribbean Sea. Wind exceeding 300 km/h and waves of more than 10 m caused a lot of damage on the islands. Saint Barth was one of the islands which took the hardest hit as the eye of the hurricane passed over its northern part. Saint Barth is home to many exclusive hotel resorts, often built very close to the beach. These hotels suffered severe damage by the storm surge and powerful waves and had to be closed for many months for restoration. Loss of income was in many occasions higher than the material loss, and the hotel owners wanted to prevent this from happening again.

Our Solution

Our analysis showed that hurricane Irma was a rare event, with a probability of occurrence of wind speed of 1 in 500 years. Detailed modelling of 32 recent hurricanes was used to derive design storm water levels and waves for reconstruction of hotel infrastructure, adopting Irma as a design event. The hotel resort is built on a steep hill, and its lower part is at significant flood risk. Considering the recreational value of easy access to the beach, full flood-proofing of the hotel was not an option. Instead, parts of the property are planned to be raised above the Irma flood level. Additional protection against overtopping waves could be realised by adding temporary measures. The buildings still in the risk zone could be made flood resilient, i.e. not to suffer significant damage in case of flooding after evacuation of their inventory after a hurricane warning. In the final design phase, we reviewed and provided recommendations to the design of erosion protection and flood proofing of the buildings.

The Outcome

Our proposed conceptual solutions and safe terrain levels were incorporated in the architectural plan for the restoration of the hotel resort. The resort is made flood resilient without losing its attractiveness and its exclusive appearance. If an Irma-like extreme event occurs again, the measures taken will prevent that hotel would have to be closed for a long time, and no expensive restoration would be needed.