River systems across Canada rely on groundwater to sustain year-round flows—particularly during dry periods—while regulating stream temperature, shaping seasonal hydrology, and buffering against climate extremes. Although much of our understanding of groundwater–surface water interactions comes from detailed reach-scale studies, translating these insights to larger spatial and temporal domains remains challenging due to hydrogeologic complexity and limited data. This session will explore groundwater contributions to river flow generation across temporal and spatial scales, with emphasis on regional integration, decadal-scale change, and drought resilience. We invite studies that apply or develop innovative methods—such as geochemical and isotopic tracers, river water age dating, terrain conductivity surveys, thermal monitoring, integrated models, remote sensing, or machine learning—to quantify and regionalize groundwater discharge. Contributions that integrate multi-proxy datasets or bridge field observations with modeling approaches are especially encouraged. Objectives: • Quantify groundwater’s role in generating and sustaining flows from reach to basin scales. • Assess seasonal, annual, and long-term variations in baseflow, including responses to drought, snowmelt, and climate shifts. • Compare and integrate methodological approaches for estimating groundwater–surface water interactions. • Foster cross-disciplinary dialogue on incorporating groundwater into river management. Themes and topics include: • Groundwater buffering capacity during droughts. • Regionalization and scaling of interaction. • Quantifying contributions from flow generating reaches (e.g., mountain block recharge). • Multi-method and data-integration approaches. • Long-term monitoring and trend detection. • Case studies from headwaters, prairie rivers, and transboundary basins.