Exploring historical anthropogenic influences on groundwater in the alluvial plain of the Upper Seine River

Human activities have significantly influenced the hydrological functioning of wetlands since they were first settled, often with the aim of reducing their perceived inconvenient wetness. Reconstructing these historical developments and understanding their impacts on hydrosystems is essential to inform strategies for the sustainable management and conservation of these vital resources. We take the example of the upper Seine valley upstream of Paris, within the vast Bassée floodplain, to illustrate and quantify how the many artificial changes it has undergone over the centuries may have had a reciprocal effect on groundwater resources. We have identified three main types of land development, ranging from hydraulic works to direct groundwater abstraction, including land use changes associated with the extraction of alluvial sands and gravels that give rise to the gravel pit lakes that are particularly prominent in the study area. Our approach is based on a detailed cartographic reconstruction of each of these influences, feeding into a hydrogeological model of the plain. We outline the main principles behind its conception and then quantify the relative impacts of anthropogenic pressures on the aquifer system budget and water table depth.