Modeling Groundwater Resource in Northern France Amidst Rising Anthropogenic Pressure and Climate Change

We present a panel of numerical modeling studies aimed to improve groundwater management resources for different contexts in the Northern part of France (the 'Hauts-de-France' Region). The objective is to demonstrate the capacities and limitations of modeling tools in reproducing observed data and providing predictions on the groundwater evolution under increasing anthropic pressures and climate change. Numerical models are developed in 3D at the regional scale to evaluate various scenarios of groundwater management, considering several types of anthropic or natural constraints such as pumping for irrigation, drinking water and/or industrial use, land use evolution, and modifications in precipitation and/or evapotranspiration due to climate change. In the three case studies presented, groundwater models are developed using BRGM’s 3D volume finite numerical tool MARTHE. The first case aims to characterize groundwater dynamics to identify the risks of flooding in the sewerage network of the urban communities of Lens-Liévin. The second case explores the role of land use in groundwater modeling for the sustainable management of the Lille Metropolitan Area. The third case evaluates the impact of climate change on the groundwater resource of the Somme River watershed. Limitations and capacities to assess such complex hydrogeological systems are discussed, particularly concerning the uncertainty in the simulated results, the CPU time and space resolution constraints necessary for a meaningful calibration of observed data.