Geotechnical approach to the filling of trench warfare landscape of the World War I

The World War I strongly marked the landscapes, especially on the western front, from Flanders to Alsace. The mine craters, shell craters, dugouts, trenches and communication trenches give off war landscapes characteristic of the front area. Theses geomorphic impacts subsist under forest cover, highlighted using the airborne LiDAR, while they are completely leveled in cultivated areas. In Champagne area, the archaeological survey linked to the urban extension of Rheims allows a better understanding of the spatial organization and the nature of the filling of these forms, by an archaeometric approach (dynamic penetrometry, mechanical oriented cross-sections, and UAV photography). Analysis conducted on an experimental area of 2 ha, in the first line of defense, makes it possible to characterize archaeological structures from the WW1 in a context of rendosols, developed on a stretched cryoclastic polygonal network, typical of the Champagne chalk surface. The results show that the forms of the WW1 are levelled by a multiphase fill with fine sedimentation synchronous with the conflict, followed by a poorly consolidated heterometric backfill. The latter coming from dismantled parados and parapet geomaterials, is rich in metallic fragments of accessory defense networks, and surmounted by an addition of topsoil. The bombturbation also determines a metallic contamination by << nugget effect >> circumscribed in the shell crater, filled with earth fillings. These anthropogenic pedoturbations determine large spatial disparities in soil water reserves (crop marks) and are associated with geotechnical and pyrotechnic risks.

Automated summary

The World War I left significant marks on the landscapes of the western front, now detectable under forest cover using LiDAR technology. Archaeological surveys and geotechnical analysis help in understanding the formation process of these war landscapes and their impact on soil water reserves, geology, and explosive risks.