Until now, research on the contribution of remote sensing for archaeological prospection has mainly been carried out in the foreshore and backshore areas. However, the need to map archaeological heritage for its protection is not limited to the lowest sea levels. Recent methodological work on the documentation of the submerged megalithic site of Er-Lannic (Morbihan) [1] has paved the way for the use of hyperspectral imagery for detecting and characterizing underwater structures in shallow water areas.

Recently, discussions initiated by Hytech-Imaging, LETG Rennes (UMR6554) laboratory and DRASSM (Département des Recherches Archéologiques Subaquatiques et Sous-Marines), have led to collaboration with SAMM team (Société d’Archéologie et de Mémoire Maritime). This multi-disciplinary partnership (geographers, divers, archaeologists, hydrographers, heritage protection authorities, etc.) resulted in a diving operation in the gulf of Morbihan, at the beginning of February.

A few years ago, the detection of a particular structure with monumental dimensions, laid on the seafloor at a depth of several metres, had sparked the interest of SRA archaeologists. Its characteristics (morphology, orientation, topographical context, variation in the seafloor nature) extracted by remote sensing, particularly airborne hyperspectral imagery, have recently confirmed this interest and have provided new elements of information.

The diving operation co-directed by SAMM and Hytech-Imaging / LETG Rennes (UMR6554), under the authority of DRASSM, allowed to collect underwater images at different points of the anomaly. During this complex operation, in conditions of limited visibility and intricate tidal currents, divers were able to identify new elements to characterize the structure. The complementary nature of remote sensing results and in-situ information contribute to the analysis and interpretation work being carried out with archaeologists from SRA and DRASSM.

A new operation is planned this summer to pursue this research.

To be continued …

[1] Guyot, A.; Lennon, M.; Thomas, N.; Gueguen, S.; Petit, T.; Lorho, T.; Cassen, S.; Hubert-Moy, L. Airborne Hyperspectral Imaging for Submerged Archaeological Mapping in Shallow Water Environments. Remote Sens. 2019, 11, 2237. https://doi.org/10.3390/rs11192237

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