Quantifying the impact of climate and management strategies on groundwater conservation in the High Plains Aquifer

Groundwater depletion in semi-arid, irrigated regions is accelerating due to intensive agricultural water use. This study uses a linked hydro-agronomic model (DSSAT-MODFLOW) to evaluate crop yield and groundwater elevation under several scenarios of future climate, irrigation system, and planting decision in Finney County, southwest Kansas, a region that has experienced significant groundwater decline over the past 50 years as a result of irrigation within the U.S. High Plains Aquifer region. Model calibration was conducted using the Generalized Likelihood Uncertainty Estimation (GLUE) based on Monte Carlo simulation. The calibrated model was applied to quantitatively assess the impacts of projected climate conditions (2021–2050), using downscaled data from seven General Circulation Models (GCMs) of the Coupled Model Intercomparison Project Phase 6 (CMIP6) under SSP245 and SSP585 scenarios, in combination with various irrigation systems and land-crop-water allocation strategies on crop yield and water table elevation. Results indicate that, under climate change alone, groundwater saturated thickness is projected to decline by 20 %–55 % by 2050. When combined with different management practices, groundwater levels continue to decline regardless of irrigation type and allocation level, indicating that groundwater resources can only be conserved but not fully sustained. Maize production becomes increasingly vulnerable without the adoption of heat- and drought-tolerant cultivars, while soybean, winter wheat, and sorghum remain more resilient across scenarios. A drier future climate condition further constrains management options that simultaneously support yield and groundwater conservation goals. These findings provide critical insights into developing adaptive irrigation and cropping strategies in the High Plains Aquifer and other groundwater-dependent agricultural regions worldwide.