Assessment of Changes in Groundwater Resources Due to Climate Change for the Purpose of Sustainable Water Management in Hungary

Climate change is increasingly affecting groundwater resources in the Carpathian Basin, and rising temperatures are expected to increase irrigation demand and pressure on aquifers; the Nyírség region in north-eastern Hungary, a hydraulically coherent recharge–discharge system, provides a suitable setting to investigate these impacts. We analysed multi-decadal groundwater levels from shallow monitoring wells (1970–2022) together with hydroclimate indicators derived from CHIRPS precipitation and ERA5-Land snow and temperature data (1981–2024). Using these inputs, we developed a MODFLOW groundwater flow model for the study area and calibrated it for representative drought and rainy periods, explicitly incorporating permitted withdrawals and estimates of illegal pumping, and applied scenario simulations to assess expected mid-century (2050) climate conditions and human-driven changes, including managed aquifer recharge options. The hydroclimate indicators show strong interannual precipitation variability alongside an overall warming and drying tendency and reduced snow storage. Scenario runs indicate declining shallow groundwater levels, with the largest decreases in higher-elevation areas, while increased pumping primarily intensifies local drawdown near major well fields. Model results suggest that direct subsurface injection is the most effective recharge approach, and water-budget analysis indicates that natural variability can drive subsurface flow changes much larger than those caused by water production, underscoring the need for integrated, long-term measures that include changes in water use.