Artificial Groundwater Replenishment in the Republic of Kalmykia: The Sources, Problems, and Perspectives

The Republic of Kalmykia is located in the northwestern part of the Caspian Region and belongs to arid regions. The issue of water resources availability is extremely relevant here. Groundwater plays an important role in this aspect as a main and often the only source of drinking water supply. However, its use is limited because of its low natural quality. An approach to an increase in the operational groundwater reserves is its artificial replenishment. The Russian Research Institute for Integrated Use and Protection of Water Resources in 2020–2021 studied the possibility of replenishing water resources of subsurface water bodies in the Republic of Kalmykia by the accumulation of surface water. The results of the studies suggested a conclusion that the artificial replenishment of groundwater in the territory of the Republic of Kalmykia is inexpedient, because even in years with the surface runoff volume with 50% exceedance probability, the volume of surface runoff will be not enough for freshening groundwater within a year to the standard level (TDS ≤1.0 g/dm3). The formation of a permanent freshwater lens (the presence of which is of particular importance in dry years) in an aquifer within the system including infiltration basin and water well is impossible because its full drawdown will take place every year.