The challenge
In the southeast of the Bay of Biscay, extreme wave height is rising, probably because of the storm conditions of the last decade, with a notable impact on beach erosion. At the same time, the risk of coastal flooding is increasing. It was necessary to better assess the impact of storms on the coast and to design measures to mitigate their effects.
The solution
AZTI led an initiative to build a broad database with detailed information on the impact of storms along the Basque coastline. On that basis, it developed a set of tools:
- Monitoring with the KOSTASystem video-monitoring network for three years on 13 Basque beaches.
- Video-based tools that measure various wave parameters and their associated impact.
- A sensor that measures the impact force of waves on coastal structures.
- Computer models that simulate flooding processes step by step.
- An early warning protocol for waves and flooding.
- A method for the town of Biarritz that analyses how often storms causing predefined economic losses will occur.
The results
- Average increase in extreme wave height of 16.8 cm per decade in the southeast of the bay.
- Increase in the area at risk of flooding of 12% by 2050 and 24% to 59% by 2100. It would grow from about 1,700 ha today to about 1,900 ha in 2050 and about 2,700 ha in 2100.
- Monitoring of the 13 beaches showed that the width and height of the dry beach, and the height of natural and artificial barriers, are key factors in reducing the impact of storms.
- Beaches with a narrower strip of dry sand are more vulnerable. Wider, higher and more sheltered beaches are less exposed to damage.
- A set of measurement, simulation and early warning tools to anticipate storms and reduce their effects.