Groundwater modelling in the Bassée alluvial plain: A tool for understanding the dynamics of a complex socio-hydrosystem

The Bassée Observatory, located in the heart of the Seine catchment and part of the Zone Atelier Seine network, is an essential research platform for understanding the hydrological processes associated with the strategic challenges of sustainable water resource management. It focuses on the behaviour of the alluvial plain as a complex and anthropised hydrosystem, considering its long-term geohistorical evolution. Through an extensive network of surface water and groundwater monitoring stations, the observatory highlights the central role of groundwater and its interactions with surface water in the current dynamics of this region. We introduce the new groundwater model of the Bassée, developed as a tool combining the CaWaQS hydrogeological platform with the groundwater utilities of the PEST parameter estimation approach. This integration improves the representation of the heterogeneity of the alluvial plain and provides a solid basis for quantitative decision making. The model is designed to assist stakeholders in addressing the challenges of operating and conserving the alluvial plain in the context of a changing environment.