Comparative Analysis of Spatiotemporal Variability of Groundwater Storage in Iraq Using GRACE Satellite Data

Iraq and other semi-arid regions are facing severe climate change impacts, including increased temperatures and decreased rainfall. Changes to climate variables have posed a significant challenge to groundwater storage dynamics. In this regard, the Gravity Recovery and Climate Experiment (GRACE) mission permits novel originate groundwater storage variations. This study used the monthly GRACE satellite data for 2002–2023 to determine variations in groundwater storage (GWS). Changes in GWS were implied by extracting soil moisture, acquired from the Global Land Data Assimilation System (GLDAS), from the extracted Territorial Water Storage (TWS). The results demonstrated that an annual average ΔGWS trend ranged for the Goddard Space Flight Center (GSFC) mascon and Jet Propulsion Laboratory (JPL) mascon was from 0.94 to −1.14 cm/yr and 1.64 to −1.36 cm/yr, respectively. Also, the GSFC illustrated superior performance in estimating ΔGWS compared with the JPL in Iraq, achieving the lowest root mean square error at 0.28 mm and 0.60 mm and the highest coefficient of determination (R2) at 0.92 and 0.89, respectively. These data are critical for identifying areas of depletion, especially in areas where in situ data are lacking. These data allows us to fill the knowledge gaps; provide critical scientific information for monitoring and managing dynamic variations.