We used an integrated approach that utilizes remote sensing (i.e., Gravity Recovery and Climatic Experiment [GRACE], Tropical Rainfall Measuring Mission [TRMM], CPC Merged Analysis of Precipitation [CMAP], Soil Moisture Active Passive [SMAP], Global Land Data Assimilation System [GLDAS], Moderate Resolution Imaging Spectroradiometer [MODIS]), geophysical (i.e., gravity and magnetic surveying), field, and geochemical (e.g., O and H isotopic composition, Cl-36, Kr-81, C-14) data together with hydrological modeling (e.g., Soil Water Assessment Tool [SWAT]) to develop a better understanding of the hydrologic setting, longevity, and optimum utilization of the Nubian Sandstone Aquifer System (NSAS) in Egypt. Specifically, we addressed the following questions: (1) Where are, and what is the nature (i.e., increasing or decreasing) of the observed temporal variations in GRACE-derived Terrestrial Water Storage (TWS) over the NSAS? (2) Is the NSAS being depleted? If it is, which part(s) are being depleted and what are the depletion rates? (3) What is the nature of the factors (i.e., climatic or anthropogenic) causing these depletions? (4) What other hydrogeologic and geologic factors are contributing to the observed GRACE-derived TWS variations? (5) For how long could the NSAS be utilized given current and/or projected rates of extraction? (6) Is the NSAS receiving modern recharge? If so, where is it receiving modern recharge? What is the recharge rate? Addressing these questions has significant intellectual merits and broad societal implications and impacts. The important intellectual merit of the proposed activities is the utilization of an integrated, innovative, and cost-effective approach to assess the groundwater potential of the trans-boundary NSAS and to develop optimum utilization techniques for it.