Results and Analysis of Coastal Cultural Heritage at Environmental Risk: Directions for Conservation and Safeguarding
Description
The Coastline Project, developed by the Laboratory of Archaeology and Conservation of Underwater Heritage, of the Polytechnic Institute of Tomar, in partnership with the non-profit association CAAPortugal. The main objective is to diagnose the risks induced by environmental factors and climate change in coastal cultural heritage. This problem has been seen as fundamental to understanding the impact of worsening climate change on safeguarding the remains recorded in the Portuguese interface area. The study takes place essentially in the interface zone up to 100 m from the coastal strip. The observations made it possible to identify the presence of 288 archaeological sites in this area (except the Algarve region), with a large part of them (204) at high risk of destruction in a time that was calculated to be less than 50 years. The research cross-references data from the Portuguese Environment Agency (APA) and records present in the database of the cultural heritage guardianship entity - Património Cultural Instituto Público (PC-IP). The high rate of sites at risk currently presents a growing concern in heritage management and the preservation of cultural traces of ancient occupation. To minimize impacts, it is proposed that the supervisory entity (PC-IP) together with a committee of researchers from different higher education institutions can consider possibilities and strategies to guarantee the study and future safeguarding of these sites. Data is shared for better management, including municipal, site analysis and development of mitigation strategies.
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There are several studies that have shown a systematic degradation of the coastline in Portuguese territory. Future forecasts, even with the application of minimization strategies, are not encouraging. This reality raises great challenges for the preservation of coastal archaeological sites, especially those located 100 m from the coastline. The Coastline project, responding to the existing problem, carried out a series of studies, cross-referencing data from different entities, in order to understand the real impact of the problem. The methodology involved taking the results observed by the APA and directly cross-referencing them with the observations and records existing in Endovélico, the PC-IP database. For our analysis, we assume a time horizon of 50 years. As specific parameters, we consider all areas affected by erosion and coastline retreat, areas affected by overtopping and flooding (considering the rise in mean sea level, astronomical tides, meteorological override, as well as the energetic impact of waves), areas near the foot of cliffs (susceptible to mass displacement and landslides), areas at the top of cliffs (with a propensity for instability and slope movements) and areas of high geological risk, with no direct relation to marine erosion. In the investigation, the Algarve region was excluded due to the lack of specific climate data predicted by the APA. This study will be conducted as soon as this data becomes available. The articles we have published regarding the Coastline project (Figueiredo & Martinville, 2024a; 2024b) have highlighted some of the limitations regarding data and perceptions on the ground, which need to be resolved to ensure good accuracy of the results. After the appropriate selection, collection and processing of data, the project proceeded to cross-reference information using ArcGIS Pro software, from Esri, from the Polytechnic Institute of Tomar. This allowed us to observe a set of general situations in addition to some limitations already widely discussed. As some archaeological sites are close to, but not directly inserted in, the risk areas, it was decided to create buffer zones, creating analysis buffers, with 100, 200 and 300 m around the risk areas identified by the APA. To differentiate the risk levels between the sites, categories were established: high risk (sites located directly in the impact zones, or within a range of less than 100 m, generally with more perishable characteristics), medium risk (sites that are integrated into buffers between 100 and 200 m or sites integrated into 100 m buffers, already outside the 100 m area of the coastline, which have more resistant structures, such as fortifications), and finally low risk (for sites that may be integrated within buffers that are 200 and 300 m away from the risk areas or between 100 and 200 m with more resistant structures). As a result, it was found that 76% of the sites are at risk.
Institutions
- Instituto Politecnico de Tomar