Heritage monitoring and surveillance using Sentinel satellite data in the Lower Alentejo (Portugal)

In this article, the potential of Satellite Remote Sensing (SRS) for large-scale monitoring of archaeological sites is analysed. This analysis focuses on the Portuguese Lower Alentejo region, where multiple sites have been destroyed over the last years, mainly due to intensive agriculture. The development of a surveillance system based on data from the Sentinel 1 and Sentinel 2 satellite constellations, named SENSEOS, had its pilot application in this region during the first half of 2019. In a vast region where authorities lacked the proper resources to timely detect events endangering the integrity of heritage sites, this system tried to overcome these issues. By using Synthetic Aperture Radar (SAR) and optical data, it was possible to detect such events through a technique labelled Normalized Difference Amplitude Index (NDAI). The identification of these changes on the surface, associated with potentially destructive events, contributed to minimize the damage and destruction of archaeological sites.