Kostarisk joint research laboratory has received government funding managed by the French National Research Agency under the France 2030 Investment Plan (ref. ANR-16-IDEX-0002).
Wave flooding and hydrodynamics load on coastal structuresPhD – Erwan Imbertie
Dates: 2021 – 2024.
Host: Rivages Pro Tech (SUEZ).
Direction: D. Morichon, M. Delpey.
Link to manuscript: https://theses.fr/2024PAUU3099
Summary – Due to increasing shoreline urbanization, coastal cities face heightened risks from ocean storms, particularly wave overtopping. Climate change-induced sea level rise exacerbates this threat, rendering existing coastal defenses progressively inadequate. This research aimed to enhance understanding of wave overtopping impacts on coastal infrastructure. The focus was on measuring and predicting maximum impact forces from post-overtopping flows on shallow to extremely shallow foreshores.
A novel field measurement system was developed and validated in laboratory conditions. Field data were collected at Grande Plage, Biarritz, in a unique setup where swash-induced overtopping occurs. Analysis confirmed some laboratory findings, such as the two-peak impact force pattern, but reveals new dynamics in high-energy impacts. Notably, the second force peak is not quasi-static in the most energetic events, contrary to previous studies. The Boussinesq-type numerical model BOSZ was used to simulate wave transformation and overtopping forces. The model was validated against large-scale flume data and applied to the Biarritz field configuration. Despite simplifications, the model reproduced key hydrodynamic features and impact forces. However, it tended to overestimate the most intense impacts under hydrostatic assumptions. An empirical correction method was proposed based on field data to refine force predictions.
The study highlights both the potential and limitations of Boussinesq modeling for post-overtopping impacts. It also emphasizes the critical value of field measurements in improving predictive coastal hazard models.
