Characterizing Pathways of Groundwater Recharge and Discharge in a Geologically and Topographically Complex Watershed

Abstract

Groundwater is a critical water source for many Canadian and First Nations communities, but the interactions between groundwater and surface water, and the impacts of climate change on groundwater recharge, are not well understood. This study investigates the Christmas Brook watershed and fault aquifer system, which supplies water to Eskasoni First Nation, Nova Scotia. The goal is to quantify the sources and flow pathways of streamflow and groundwater recharge feeding the pumping wells, informing watershed management. Water sampling, hydrochemical analysis, hydrometric monitoring, and groundwater modeling were used. A total of 134 samples were analyzed for ions, isotopes, and metals. Gauging stations were installed at the highland wetland outlet and lowland watershed outlet. Hydrochemical results show groundwater contributes 27 ± 15% of streamflow at the downstream station. A MODFLOW6 model indicates streamflow infiltration provides 60% of pumping well water, with the remaining 40% from fractured rock recharge.