Geomatic multiscale approach for the conservation of archeological sites: the case of Alba Fucens (L'Aquila-Italy)

The archaeological site of Alba Fucens (L’Aquila, Italy) (303 BC) is the largest archaeological area of the whole Apennines. Extension, location and environmental context of the site require new methods for risk mitigation and conservation. In this paper, a multiscale geomatic approach, based on remote sensing and UAV photogrammetry, is reported. The main purpose is the extraction of architectonic and weathering information, useful for a better fruition and conservation. For a multiscale approach, very high resolution satellite images (WorldView2) and UAV Photogrammetry technique have been used. The satellite image processing, performed by Normalized Difference Vegetation Index (NDVI), High-pass filter, Principal Component Analysis (PCA) and classification, allowed to detect buried or emerging structures and to estimate fire and erosion risks. On the other hand, UAV photogrammetry technique allowed to evaluate detailed architectural information of the buried (ima, media and summa caveae) and excavated amphitheatre structures (arena, podium and steps). Furthermore it was also possible to systematically acquire complete and reproducible data on stone materials (limestones) and their weathering (loss of stone material, natural or anthropogenic break out, deposits, efflorescences, dark or light crusts, biological colonization, granular and crumbly disintegration, flaking and fissures). With a multiscale and metric approach, the geomatic techniques allow to deeply investigate the monument-mapping and to create a detailed 3D models. In this way, the stone decay, the risks and their mechanisms can be evaluated, in order to plan and perform future actions and interventions for their mitigation.