remote sensing Article Lost Landscape: A Combination of LiDAR and APSFR Data to Locate and Contextualize Archaeological Sites in River Environments Esther Rodríguez González * , Pablo Paniego Díaz and Sebastián Celestino Pérez Instituto de Arqueologia (CSIC—Junta de Extremadura), 06800 Mérida, Spain; [email protected] (P.P.D.); [email protected] (S.C.P.) * Correspondence: [email protected] Abstract: Over the last few decades, river landscapes have been significantly transformed as a result of increased human impact. This transformation is evident in areas such as the middle Guadiana basin, where the impact of both agricultural and hydraulic infrastructures has led to the decontextualization of archaeological sites, resulting in a disconnection between archaeological sites and their own physical environment. In order to analyse the location and geographic contexts of sites from the first Iron Age in the middle Guadiana basin and to detect the existence of human settlement patterns, we designed a methodological approach that combines LiDAR and APSFR data (areas with potential significant flood risk). The main purpose of this method is to detect flood areas and assess the relationship between them and archaeological sites. The result allowed us to obtain a clearer understanding of these societies, their knowledge of the physical environment, and the causes Citation: Rodríguez González, E.; and reasons behind their occupation of certain sites. The validation of the results demonstrated the Paniego Díaz, P.; Celestino Pérez, S. versatility of this methodological approach, which can be extrapolated to analysing other regions Lost Landscape: A Combination of and historical periods. LiDAR and APSFR Data to Locate and Contextualize Archaeological Keywords: Sites in River Environments. Remote LiDAR; potential flood risk; aerial archaeology; landscape archaeology; Tartessos; middle Sens. 2021, 13, 3506. https:// Guadiana basin doi.org/10.3390/rs13173506 Academic Editors: Antonio Monterroso Checa and Dimitrios D. 1. Introduction Alexakis The middle basin of the River Guadiana is an extensive area in the southwest of the Iberian Peninsula (Figure1). It is structured around one of the main rivers of the peninsula, Received: 16 June 2021 the Guadiana, which has a hierarchical network of tributaries that make it a fundamental Accepted: 31 August 2021 artery of communication. The Guadiana is a low-lying river, shallow and easy to ford [1] Published: 3 September 2021 (p. 29), making it an essential element that must be present in any analysis of ancient settlement in this region, given the migratory role the river played. Publisher’s Note: MDPI stays neutral The fertility of the soil along the Guadiana River has favoured the occupation of the with regard to jurisdictional claims in area from prehistoric times to the present day. However, local archaeological remains are published maps and institutional affil- in a poor state of preservation, due to agricultural work carried out in the area, which has iations. led to the transformation of the landscape and the destruction of a large number of sites that are hidden under the current croplands. To overcome this situation, archaeologists use different landscape analysis tools and methodologies and remote sensing to facilitate our work by creating predictive models that give us a better understanding of how the Copyright: © 2021 by the authors. landscape functioned in ancient times. The final aim of this work is to historically interpret Licensee MDPI, Basel, Switzerland. the cartographic data to understand the relationships that ancient societies in the area had This article is an open access article with the landscape in which they lived. distributed under the terms and Given the close relationship between the Guadiana River and the settlement of this conditions of the Creative Commons territory, in order to determine to what impact the river course has had on the settlements, Attribution (CC BY) license (https:// and more specifically settlements from the first Iron Age, we designed an analysis strategy creativecommons.org/licenses/by/ that incorporates data from the calculation of Areas with Potential Significant Flood Risk 4.0/). Remote Sens. 2021, 13, 3506. https://doi.org/10.3390/rs13173506 https://www.mdpi.com/journal/remotesensing Remote Sens. 2021, 13, 3506 2 of 28 (APSFR) provided by the Guadiana River Hydrographic Confederation (CHG, dependent on the Spanish Ministry for Ecological Transition and Demographic Challenge); the tradi- tional study carried out from the review of current and historical aerial photographs, and the spatial analysis made from the data provided by LiDAR flights. Calculating the flood areas of the Guadiana riverbed and of some of its main tributaries allows us to delimit the area within which the course of the river shifted, hence the importance of this study and of the methodology it contains. With this image, we can determine the position of the sites with respect to the river, their distance or proximity, and estimate to what extent a site is impacted, or the symbolic significance of the places that were chosen to locate a site. Although the working methodology presented in this article can be applied to any chronology, since the main variable of this formula is the location of the sites with respect to the watercourses in each historical moment, we selected the period comprising the first Iron Age in the middle Guadiana basin, between the seventh and fifth centuries BC. At this moment in time, the area was experiencing demographic growth as a result of the crisis that occurred in the heart of Tartessus, the Guadalquivir valley [2], which would Remote Sens. 2021, 13, 3506 result in the appearance of a new model of settlement that was unparalleled in other3 of 29 Mediterranean regions. FigureFigure 1. Map 1. Map showing showing settlements settlements inin thethe middle middle Guadiana Guadiana basin basin during during the firstthe Ironfirst Age.Iron 1.Age. Huerta 1. Huerta de Don de Mateo; Don 2. Mateo; Casas 2. Casas del Cerro de la Barca; 3. Cañada la Virgen; 4. Miraflores; 5. Lácara; 6. Turuñuelo de Mérida; 7. El Tiriñuelo; 8. Turu- del Cerro de la Barca; 3. Cañada la Virgen; 4. Miraflores; 5. Lácara; 6. Turuñuelo de Mérida; 7. El Tiriñuelo; 8. Turuñuelo ñuelo (Villagonzalo); 9. Las Madalenas; 10. Casas del Turuñuelo: 11. Las Lomas; 12. La Aliseda; 13. La Mata; 14. Cancho (Villagonzalo); 9. Las Madalenas; 10. Casas del Turuñuelo: 11. Las Lomas; 12. La Aliseda; 13. La Mata; 14. Cancho Roano; Roano; 15. El Tamborrio; 16. Escuela de Hostelería (Mérida); 17. El Chaparral; 18. El Palomar; 19. La Marquesa; 20. Mede- 15. El Tamborrio; 16. Escuela de Hostelería (Mérida); 17. El Chaparral; 18. El Palomar; 19. La Marquesa; 20. Medellín; 21. La llín; 21. La Veguilla; 22. Cerro Manzanillo; 23. Cerro de la Barca—Torruco; 24. Media Legua; 25. La Carbonera; 26. La Mata Veguilla; 22. Cerro Manzanillo; 23. Cerro de la Barca—Torruco; 24. Media Legua; 25. La Carbonera; 26. La Mata de Cancho de Cancho Roano; 27. Las Reyertas; 28. Necropolis of Aljucén; 29. Necropolis of El Pozo; 30. Necropolis of Valdelagrulla. Roano; 27. Las Reyertas; 28. Necropolis of Aljucén; 29. Necropolis of El Pozo; 30. Necropolis of Valdelagrulla. 2. TheThe Middle population Guadiana of the Basin: middle An Guadiana Anthropized basin Territory during the first Iron Age was charac- terisedIn order by the to presenceunderstand of large the importance structures at of the th confluenceis study, it ofis theimportant Guadiana to consider and some the profound changes that the landscape of the central Guadiana basin has undergone over the last century, and how this process has affected the archaeological record. The transformation of the Vegas del Guadiana experienced a major boost in the 1950s, when the General Economic and Social Development Plan for the Province of Badajoz, known as the Badajoz Plan, began to be implemented [4]. The work plan included the construction of hydraulic infrastructures, the adaptation of the necessary roads in the ir- rigation area, and the construction of new villages to house workers. The project included the irrigation of more than 120,000 hectares, the construction of 60 villages, and the plan- ning of 8 reservoirs and 4 irrigation canals [5]. This colossal project entailed a radical change in the structure and image of the land- scape, which went from being represented by large expanses of unirrigated land to being a green, irrigated landscape with alternating crops of tomato, rice and maize. This change also entailed the replacement of the native vegetation of the territory and the destruction of a large number of enclaves, irretrievable information that has left little trace in the ar- chaeological record (Figure 2). Remote Sens. 2021, 13, 3506 3 of 28 of its main tributaries. There is only one exception to this pattern: the sites of Cancho Roano (Zalamea de la Serena, Badajoz, Spain) and La Mata (Campanario, Badajoz, Spain) located inland to the south of the river. All these structures have several characteristics in common, starting with the material used for their construction (adobe) and the way in which they were re-used. After their destruction and abandonment, these buildings were hidden under a large artificial mound that helped to conserve them until the present day. Along with the so-called Tartessian buildings hidden under tumuli, the settlement model is completed with the presence of settlements on high ground, village and farm-type sites on plains,