WATERSHED-SCALE RESPONSE OF GROUNDWATER FLOW SYSTEM TO DECADAL FLUCTUATIONS OF METEOROLOGICAL CONDITION

A groundwater flow system can be seen as a continuum consisting of recharge by precipitation inputs, storage in aquifers, and discharge to streams. Surface water (SW)-groundwater (GW) interaction plays important roles in both recharge and discharge ends of the flow system. In the Canadian prairies characterized by cold, semi-arid climate and glaciated terrain, groundwater recharge is strongly influenced by SW-GW interaction in topographic depressions. Decadal-scale fluctuations of precipitation inputs cause fluctuations of recharge fluxes, which in turn cause fluctuations of aquifer storage and stream baseflow. Using a unique citizen-science approach, groundwater levels in bedrock aquifers have been monitored for nearly two decades in a small (250 km²) prairie watershed in Alberta, Canada. The water level data are analyzed together with long-term baseflow data and groundwater recharge time series simulated by a numerical model of depression-focussed recharge. The results demonstrate the watershed-scale response of the groundwater flow system to meteorological fluctuations and its resilience over a multi-decadal period.