Groundwater recharge dynamics to recent wetting in a cold region aquifer

Oakes aquifer, Northern Great Plains (NGP), North Dakota, USA Groundwater recharge in cold regions is governed by complex interactions among snow processes, soil freezing dynamics, and seasonal precipitation. In the northern Great Plains, field-based recharge studies integrating physically based modeling remain limited, despite the region’s climate sensitivity. This study addresses key knowledge gaps by estimating groundwater recharge to the Oakes aquifer in southeastern North Dakota for the 1991–2024 water years, using field observations and process-based models: the Cold Region Hydrological Model (CRHM) and HYDRUS-1D. Simulations were evaluated using snow water equivalent (SWE) and multi-depth soil moisture data, including winter field campaigns at ten sites during 2022–2024. Results show that spring and summer rainfall is the main recharge source, while snowmelt contributes variably depending on frozen soil and winter temperature. Cold winters prolong soil freezing, reducing infiltration and increasing runoff. Snowmelt-related recharge does not consistently decline with cooling but depends on its intensity and precipitation totals. Recharge also shows strong spatial variability tied to surface and subsurface properties. Coarser soils yield more recharge, while finer soils limit infiltration. Elevation, land cover, and surface depressions further influence recharge patterns. These findings demonstrate that combining field data with physically based models provides a robust framework for quantifying recharge in cold regions and offers insight into how snowmelt, rainfall, and climate variability interact with landscape features to control groundwater recharge in cold region aquifers. • Field data with process-based models improve recharge estimates in cold regions. • Rainfall dominates recharge; snowmelt depends on winter temps and frozen soil. • Soil texture controls recharge: coarse soils enhance infiltration.