Simulation of long-term spatiotemporal variations in regional-scale groundwater recharge: contributions of a water budget approach in cold and humid climates

Abstract. Groundwater recharge (GWR) is a strategic hydrologic variable, and its estimate necessary to implement sustainable groundwater management. This especially true in global warming context that highly impacts key winter conditions cold humid climates. For this reason, long-term simulations are particularly useful for understanding past changes GWR associated with changing climatic conditions. However, simulation at the regional scale challenging, due limited availability of spatially distributed calibration data generally short observed time series. The objective study demonstrate relevance using water budget model understand transient regional-scale climates where observations scarce. HydroBudget was specifically developed climate uses commonly available such as runoff curve numbers describe area, precipitation temperature series run model, river flow rates baseflow estimates automatic calibration. A typical case presented southern portion Province Quebec (Canada, 36 000 km2). With simultaneously calibrated on 51 gauging stations, first region simulated between 1961 2017 very little uncertainty (? 10 mm/yr). divided into 41 % (444 mm/yr), 47 evapotranspiration (501 12 (139 preferential periods during spring (44 32 annual GWR, respectively), values other Snowpack evolution soil frost were shown be feature these environments. One contributions show sensitivity parameters correlated average air temperature, colder watersheds more sensitive snow-related than warmer watersheds. Interestingly, results showed significant increase since early 1960s did not lead but resulted increased evapotranspiration. In contrast previous studies trends climates, work has have yet produced GWR. Because their relative ease use, models approach scientists, modelers, stakeholders alike renewal if they can easily adapted specific needs