Unmanned aerial vehicles (UAVs) for coastal protection assessment: A study of detached breakwater and groins at Marawila Beach, Sri Lanka

Abstract

Coastal protection plays a vital role in mitigating coastal hazards and erosion risks. However, the effectiveness of various global coastal protection structures is questionable due to the uncertainties they face. Many developing countries struggle to evaluate the long-term productivity and efficiency of these structures, primarily due to the lack of reliable and affordable monitoring methods. To address this problem, this study used an approach based on unmanned aerial vehicles (UAVs) for coastal monitoring to assess the effectiveness of coastal protection structures on Marawila Beach, Sri Lanka, where different structures have been implemented. The UAV imagery was analyzed using photogrammetric techniques as a pilot study to estimate shoreline changes, erosion rates, and sediment transport patterns. The results demonstrated that coastal protection structures significantly reduced erosion rates and sediment transport compared to unprotected areas. Among the structures, the detached breakwater proved to be the most effective in reducing erosion rates and sediment transport, while the groins showed moderate effectiveness. This study's findings significantly contribute to evaluating the effectiveness of coastal protection structures and highlight the value of UAV-based coastal monitoring as a cost-effective and efficient alternative to traditional methods.