Quantifying Recent Recharge to the Saq Transboundary Aquifer System using an Integrated Geophysical, Geochemical, and Remote Sensing-based Approach

Abstract: The Saq aquifer system represents one of the most significant transboundary aquifers in the Arabian Peninsula that extends between northern parts of Saudi Arabia, Iraq and Jordan. Recent studies show that the Saq aquifer system is witnessing rapid groundwater depletions of -6.52 ± 0.29 mm/year (-3.49 ± 0.15 km3/year) that are highly correlated with increasing groundwater extraction for irrigation and observed water level declines in regional supply wells. In addition, the region is receiving record low amounts of precipitation in recent years. Thus, quantifying the groundwater recharge rate of the Saq is essential to sustainable present and future utilization of the groundwater resources in that system. In this study, we develop and apply an integrated Geophysical, Geochemical, and Remote Sensing-based approach to quantify the recharge rates of the Saq aquifer system given the areal distribution of the Saq transboundary aquifer system, the interaction between the Saq aquifer and the overlying aquifers, as well as the very limited rates of recharge through precipitation. Specifically, we set out to accomplish the following: (1) delineate and examine the areal extent of the Saq aquifer recharge domains using geologic, climatic, and remote sensing data; (2) investigate the origin of, and recent contributions to, the groundwater in the Saq aquifer system by examining the isotopic compositions of groundwater samples collected from the Saq aquifer; and (3) estimate, to the first order, the magnitude of modern recharge utilizing the Gravity Recovery and Climate Experiment (GRACE) data and rainfall time-series of the region. Results from this paper will help us to apply the suitable location for drilling and determine the best extraction scenarios.