Identifying Coastal Heritage Vulnerabilities: The Case of Historical Fortified Structures in Northern Portugal

Landscapes and heritage sites hold significant historical, scientific, and social value but face increasing threats from climate change and human activities. Coastal and maritime heritage are at risk from sea-level rise, storms, erosion, ocean acidification, and pressures such as urbanization, construction, and industrial development. Assessing vulnerability involves considering physical, geomorphological, and socioeconomic factors, including land use, population density, tourism, and ecosystem sensitivity. Long-term monitoring, interdisciplinary research, and holistic approaches are essential for effective risk assessment and planning. This study focuses on the coastal landscapes of northern Portugal, where climate change adaptation is urgent. These areas contain important historical heritage, especially fortified military structures that reflect regional identity and maritime history shared with other coastal nations. The research highlights significant risks to these monuments because of their proximity to the sea and expanding urban areas, providing insights to guide policymakers and support localized adaptation strategies. A two-phase methodology was employed, beginning with a comprehensive literature review to identify key indicators that informed field observations, surveys, and archival research, resulting in a detailed inventory of coastal and estuarine fortifications. The second phase assessed their vulnerability to sea-level rise, coastal flooding, and shoreline retreat. The study presents a methodological approach that provides local decision-makers with strategic guidance to enhance the protection and sustainable management of coastal heritage.