Geoarchaeology of the middle Herault valley (southern France) since the Bronze Age: cartographic approach

While the concept of the Anthropocene is still debated, it seems crucial to deepen our knowledge of the interactions taking place between human societies and their environment. Occupied for at least the Bronze Age, the middle Herault valley offers a territory suitable for the analysis of these interactions thanks to the wealth of archaeological data uncovered and their proximity to river activity. In order to do this, we determined the nature of the hydromorphological evolution of the Herault River and their impact on the fluvial landscape, through a comparative analysis of the cartographic data, making it possible to identify the morphogenic capacities of the river. By crossing the results of geomorphological, hydromorphometric, palaeogeographic and archaeological analysis, we were able to define three sections in the floodplain, each characterised by its own dynamics. The first section is distinguished by the flow of the river in a deep channel and the poor development of the Holocene terrace. The palaeogeographic analysis revealed a relative conservation of the fluvial hydrography. Consequently, on this section, the hydrological functioning of the river has little impact on the evolution of the alluvial landscape. The second section particularly stood out from the rest of the valley following the analysis of the hydromorphometric data. The frequency and amplitude of the meanders on this section is 3.7 times greater than the average observed over the entire middle valley. Consequently, the fluvial landscape of this section is characterized by a greater instability. Finally, the third section was characterised by the narrowing of the channel, a decrease in its depth and a vast expansion of the Holocene terrace, reflecting a strong dynamic of alluviation.