Unraveling the Morphological Constraints on Roman Gold Mining Hydraulic Infrastructure in NW Spain. A UAV-Derived Photogrammetric and Multispectral Approach

Javier Fernández-Lozano,Enoc Sanz-Ablanedo

doi:10.3390/rs13020291

Abstract

The province of León preserves a unique hydraulic infrastructure 1200 km-long, used for the exploitation of auriferous deposits in Roman times. It represents the most extensive waterworks in Europe and is one of the best-preserved examples of mining heritage in Antiquity. In this work, three mining exploitation sectors (upper, middle, and lower) characterized by channels and leats developed in different geological materials were examined, using Unmanned Aerial Vehicles (UAVs). A multi-approach based on a comparison of photogrammetric and multispectral data improved the identification and description of the hydraulic network. Comparison with traditional orthoimages and LiDAR data suggests that UAV-derived multispectral images are of great interest in areas where these sets of data have low resolution or areas that are densely covered by vegetation. The results showed that the size of the channel box and its width were factors that do not depend exclusively on the available water resources, as previously suggested, but also on the geological and hydraulic conditioning factors that intervene in each sector. Additionally, the detailed study allowed the establishment of a water sheet maximum height that was much lower than previously thought. All in all, these inferences might help researchers develop new strategies for mapping the Roman mining infrastructure and establishing the importance of geological inheritance on the construction of the hydraulic system that led the Romans to the accomplishment of the largest mining infrastructure ever known in Europe.

Highlights

The Roman hydraulic network and associated mining infrastructure represent one of the largest and best-preserved examples of engineering works in Antiquity
The Unmanned Aerial Vehicles (UAVs)-derived data obtained consisted of a high-resolution orthomosaic, a multispectral image, and a digital surface model (DSM) from the different mining sectors (Figure 4)
A combination of different methodologies enhances the detailed analysis of the hydraulic network. The value of these tools lies on their ability to know how to take advantage of the technique, depending on the extrinsic and intrinsic conditioning factors that make the study of hydraulic network difficult, adapting the research needs to the appropriate methodology in each case

Summary

Introduction

NW Spain and Portugal concentrate a large number of Roman gold works (Figure 1a) that were systematically studied by archaeologists since the early 1970s [4,5,6,7,8,9], but considerable progress was made in its identification and description in the past decades [10,11,12,13,14] Despite most of these studies focusing on the archaeological interest of the hydraulic network and the analysis of the territory, in recent years, there is a renewed interest on in the geological information surrounding the mining infrastructure [15,16].

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Discussion

Conclusion