Enhancing coastal resilience: assessing the efficacy of nature-based solution for beach-dune system management and foredune restoration

Context/Purpose: Coastal dunes are critical in safeguarding coastal regions against flooding and erosion. However, they face significant global challenges due to human activities, climate change, and rising sea levels. Implementing nature-based solutions has emerged as a successful approach to restore dune morphologies and combat degradation. This study aims to assess the effectiveness of sand fences in promoting sediment accumulation within the foredunes of Costa Brava beach two years after their installation. Methods: Unmanned aerial vehicle (UAV) data were collected both before and after the installation of sand fences at el Riuet beach to generate high-resolution (15 cm) digital elevation models. Results: Installing sand fences has proven to be highly effective in increasing sediment deposition within the foredune area. According to the initial volume in 2019 (23,590 m3) and the final volume in 2023 (32,540 m3), there was an increase of 38% after installing sand fences, corresponding to 8,950 m3. Interpretation: The captured sand has played a role in reinstating the slope of the beach-dune profile, a crucial factor for the stability and integrity of coastal ecosystems. Nevertheless, this study shows that certain sand fences perform better with higher porosities than commonly recommended, indicating a lack of consensus in current scientific literature. Conclusion: Installing sand fences on dunes is an effective nature-based solution