Using airborne LiDAR sensing technology and aerial orthoimages to unravel roman water supply systems and gold works in NW Spain (Eria valley, León)

Abstract

LiDAR technology, based on Earth's surface scanning, allows the compilation of high resolution digital terrain models. Recently used in archaeological works for the discovery and description of heritage features such as ancient human-made structures and building ruins, it is particularly effective in areas with dense vegetation or difficult access, where surveying becomes complicated. Among its main advantages over other traditional methods of archaeological research, it highlights the possibility of controlling display parameters, which in turn facilitates data analysis and interpretation. In this study we present an integrated LiDAR and aerial photography data analysis in order to obtain a detailed map of ancient mining works within a small sector of the Roman mining district in northwestern Spain. The presence of gold deposits led to intensive extractive work during the first century b.p.t. Although many of the mining activities were focused on the northwestern area of Las Médulas and Omañas, large deposits were also found along the Duerna and Eria river valleys. Our results complement previous work carried out in the Eria area (Valdería), providing new insights into the hydraulic engineering techniques and the geometry of the main Roman exploitations. This work highlights the scope of the ancient mining works and their impact on the landscape, which are much greater and more important than previously thought.