Numerical Modeling of Transboundary Groundwater Flow in the Bug and San Catchment Areas for Integrated Water Resource Management (Poland–Ukraine)

On the Polish–Ukrainian borderlands, there is the Lublin–Lviv transboundary groundwater aquifer system, which is of key importance in shaping strategic groundwater resources. Due to the particular importance of this aquifer system, the two neighboring countries are obliged to undertake joint actions to protect it. The integrated management of the Lublin–Lviv aquifer system seems difficult due to the significant spatial and temporal scale of groundwater flows in the region. To support internationally integrated management, a transboundary geological model was developed. Based on this model, a hydrogeological conceptual model has been developed, which allowed for a numerical model of groundwater flow to be calculated. The model research helped diagnose potential problems by determining the scope of the area with cross-border flows and quantifying the flows between Poland and Ukraine. In addition, the numerical model was used to define the optimal cross-border management unit and the conditions needed to sustainably exploit the Lublin–Lviv aquifer system. Basing on the research results it was concluded that groundwater flows in transboundary aquifers very on a regional scale and that the range of areas of importance for transboundary groundwater flows is much smaller than the pre-selected partial catchments of the Bug and San Rivers. The results of this study may significantly contribute to the preparation of joint water management plans.