Abstract

Groundwater–surface water interaction (GSI) is a critical component of the hydrological cycle, and its understanding is essential for effective water allocation, ecosystem health, and contaminant transport management. The magnitude of GSI is controlled by the aquifer properties, the hydraulic gradient (both natural and anthropogenic, such as groundwater pumping), and the type of surface water body. Heterogeneity in aquifer properties further complicates the quantification of GSI, highlighting the integration of field-based measurements and numerical modelling methods. This presentation examines GSI across different aquifer systems. It will demonstrate how aquifer properties, temporal variability in hydraulic gradients, and climate impacts control the transition between gaining and losing conditions. Findings emphasize the importance of a well-conceptualized model to adequately characterize GSI processes. An improved understanding of these interactions is essential for decision-makers to develop effective policies and sustainable water management strategies across Canadian watersheds.