Sustainable management of groundwater resources requires accurate calculations of the underground water budget as a basis for decision-making. However, as water systems are complex and vary in space and time, water budget estimations come with significant uncertainties. Moreover, unregulated (and therefore unknown) groundwater extraction by industries, agriculture, and households poses a significant obstacle to sustainable use. This study determines the water budget of regional aquifers by comprehensively incorporating all source/sink terms, including unregulated and unknown groundwater extraction, while capturing and quantifying the resulting overall uncertainty. Methods for assimilating data from modern and state-of-the-art data collection methods, including remote sensing, will be proposed. Computational tools for uncertainty analysis with the potential to include additional data sources will be developed. Through multi-objective optimization, optimal monitoring schemes will be suggested to further reduce uncertainty. The proposed study aims to provide the necessary methods to close the water budget of aquifers considering uncertainty and unregulated groundwater extraction, contributing to efficient planning and management of groundwater resources.
