Long-Term Assessment of Groundwater Recharge in the Amalie Lany Aquifer, the Czech Republic, from 1990 to 2089

Abstract. The influence of climate change on groundwater levels and recharge remains insufficiently quantified, particularly in low-precipitation regions where groundwater is a critical water-supply source. In the Czech Republic, groundwater abstraction for public supply reached 366 million m³ between 1990 and 2020. Over the same period, the Amálie Lány site in Central Bohemia experienced warming, with maximum air temperature increasing by 1.1–1.5 °C and minimum air temperature by approximately 1 °C, accompanied by a slight decrease in mean annual precipitation of about 50 mm. These hydroclimatic shifts can intensify drought by increasing atmospheric water demand and altering soil moisture, infiltration, groundwater recharge, and water-table dynamics.

This research estimates long-term groundwater recharge (1990–2089) using a physically based framework that couples the Richards equation with heat transport and an energy-balance top boundary to represent liquid, vapour, and heat fluxes, including phase change. The analysis targets an unconfined carbonate aquifer system in western Central Bohemia, where infiltration is the dominant recharge mechanism. Forcing data combine ERA5 hourly meteorology and local observations (1990–2020) with climate projections (1990–2089) under four Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5) using precipitation, temperature, wind speed, cloud cover, solar radiation, and relative humidity.

Recharge was simulated with the Richards equation in the open-source DRUtES platform using coupled liquid, vapour, and heat transport. The model represents two observation boreholes within compacted sedimentary layers underlain by fractured formations and incorporates key hydraulic and thermal parameters (van Genuchten properties, anisotropy, thermal conductivity, and root-zone characteristics). Results are reported per decade averages across observation points in the soil profile.

Recharge trajectories diverge markedly between scenarios. Under SSP1-2.6, recharge remains relatively stable, whereas higher-emission pathways produce a sustained decline, reaching reductions of up to ~50 % by late century under SSP5-8.5. The findings highlight precipitation and atmospheric demand as dominant controls on recharge and underscore risks to water security under continued warming.