Assessing the Effect of Climate Change in the 21st Century on Groundwater Balance in the Southwestern Crimea

A regional groundwater flow model of the southwestern Crimea within the Alminskii Artesian Basin and the adjacent area of fracture-karst groundwater of Mountain Crimea was developed and calibrated for the current period. Numerical experiments with this model were used to evaluate the changes in groundwater resources under the effect of forecasted climate changes in the 21st century. For this purpose, forecast maps of infiltration recharge were constructed for the study area. The forecast maps of infiltration recharge were constructed from the lowland part of the area with the use of simulation of infiltration water exchange. In the mountain part, the changes in recharge were forecasted taking into account both the infiltration water exchange and the influation, i.e., influation of precipitation into karst forms. The forecast scenario was taken to be the extreme scenario of climate changes SSP5-8.5, implying maximal warming, and an ensemble of Atmosphere-Ocean General Circulation Model of the CMPI 5 family. Three models with the highest contrast of changes in the aridity index were selected from the ensemble forecast, and forecast maps of recharge changes in the 21st century were obtained for them and used in numerical experiments. The total infiltration recharge appreciably differs from its current value—366.4 thousand m3/day: at dry climate, the infiltration recharge is 187.9 thousand, at moderate climate, it is 283.6 thousand, and at humid climate, it is 403.3 thousand m3/day. The results of the forecast modeling of groundwater balance during the 21st century with the use of the maps of infiltration recharge showed a high adaptive role of the storage reserves and the decrease of minimal river runoff at the considered time scale of the order of a hundred years at the current level of groundwater intake.