Remote sensing and GIS techniques for reconstructing the military fort system on the Roman boundary (Tunisian section) and identifying archaeological sites

Abstract

Southern Tunisia is one of the most significant areas of historical and archaeological interest as, since the Roman period, it has played a key role as a land bridge controlling the passage from the Saharan plain to plateaus and to the north of the mountain range between Chebika and Metlaoui. Because of the difficult geography, the investigation of ancient sites in this region is not easy and, therefore, satellite-based investigation can play an important role in the detection and documentation of archaeological sites. In this study, we combined high-resolution remote sensing (RS) imagery with in situ investigations to assess the suspected archaeological sites detected using satellite data and historical documentation. The suspected sites were confirmed according to the geometric features of the sites as they appeared in the remotely sensed imagery these sites had not been detected during earlier field investigations. In particular, we aimed to use 1-m spatial resolution WorldView-2 (WV2) imagery of the Wadi El-MelahValley (WMV) in Gafsa (also named Capsa). The satellite data were processed using statistical analysis and unsupervised classification.WV2 satellite imagery of WMV, Southwestern Tunisia, was processed within ArcGIS 10.2 to identify spatial features linked to the sites. The study outlines three different feature-extraction methods (GIS-based, unsupervised classification-based and statistical analysis-based). The satellite-based analysis and archaeological records were evaluated by RS and GIS prospecting in the area of the field survey to confirm the new discoveries. The results of remotely sensed data combined with field survey enabled us to reconstruct the military defense system consisting of is a linear defensive structure (limes) and forts related to the Imperial Roman period. Taken together, the results of our investigations provide new insights into some important sections of the Roman limes in the southern part of the empire. Other concealed remains are still to be found and explored.