Quantifying groundwater discharge to surface reservoirs

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Over the past 50 years, the global groundwater extraction rate has at least tripled. Climate change, deforestation or urbanization add additionnal pressures on groundwater resources. These stresses are of very current importance, as groundwater level declines have now been recorded in every state of the USA, possibly jeopardizing river baseflows and groundwater dependent ecosystems. The conditions, triggers and thresholds under which gw-sw connectivity is established or compromised are still poorly understood. In the coming years, my long-term objective will be to develop innovative approaches to quantifying aquifer discharge to surface reservoirs and to quantifying the vulnerabilty of discharge to natural and human-induced changes. My short-term objectives are: 1) to develop a science-based typology of groundwater discharge to surface reservoirs; 2) to quantify the meso-scale at which groundwater discharge is usually determined; and 3) to define indicators reflecting current conditions that can be used to identify discharge changes. Each objective will be met by undertaking two HQP studies. PhD1 will focus on constraining the location of groundwater discharge areas using high-precision topographic LiDAR data. MSc1 will aim at better understanding how short-term changes in discharge are influenced by geological and hydrological conditions. PhD2 will aim at understanding the meso-scale driving forces and conditions governing groundwater discharge in hydrogeological contexts typical of southern Canada. MSc2 will focus on the processes responsable for meso-scale recharge, including freezing and thawing. PhD3 will disentangle the complex problem of understanding groundwater discharge for the entire St. Lawrence Lowlands and develop indicators of groundwater discharge. MSc3 will use a subset of the models of targeted watersheds to determine the impacts of climate change, land use change and mitigation measures on groundwater discharge. The combination of state-of-the-art field work and modelling approaches applied for a variety of conditions is unique and original. This research will fill knowledge gaps on the processes and scales driving groundwater discharge, provide new ways of estimating current conditions and identify future pressures. It is expected to produce benchmark, highly cited publications. This will be made possible by the training of HQP (3 PhD, 3 MSc, 2 BSc) who will participate in a unique multi-disciplinary team of top researchers in the field of hydrogeology. They will be prepared to face the complexity of field and modelling work common to hydrogeology and environmental studies. This research program has the potential to change the way groundwater is included in water management policies and to contribute to the resilience of groundwater dependent ecosystems and groundwater resources.