Estimation of groundwater contributions to Athabasca River, Alberta, Canada

Study region: The Athabasca River Basin (ARB), CanadaStudy focus: This study investigates the dynamic interactions that occur between surface water and groundwater systems within the Athabasca River Basin (ARB). The integrated surface -subsurface model of the ARB was first calibrated under monthly normal transient flow condi-tions to observed surface water and groundwater data, after which the model was forced with monthly average transient data to evaluate model performance. From these results, groundwater contribution to the Athabasca River system was calculated using simulated surface water -groundwater exchange fluxes. These estimates are compared to those obtained from an isotope-based balance analysis which also estimated groundwater contribution to the Athabasca River.New hydrological insights for the region: The results from this study suggest that the groundwater system in the basin has a high degree of interaction with the surface water system. Specifically, the groundwater contribution to the surface water system along the Athabasca River ranges from 34% (high flow season) to 63% (low flow season) with an overall average annual groundwater contribution of 45%. These results indicate that the groundwater system needs to be considered when analyzing potential climate change impacts on future water availability and extreme hydroclimatic events.