Monitoring temporal variations in water resources across the Arabian Peninsula and identification of their controlling factors

Assessment, monitoring, and development of the fresh water resources in the Arabian Peninsula (AP) are critical for the sustenance of the AP's growing population and water consumption. Monthly (01/2003-12/2013) Gravity Recovery and Climate Experiment (GRACE) data along with other relevant climatic, geologic, hydrogeologic, and remote sensing datasets were used to monitor the spatiotemporal variability in the AP's water resources and to investigate the causes of those variations. Four regions were selected; in our selection, we tried to cover major aquifers, follow political boundaries, and exceed GRACE footprint (~0.20×106 km2) to minimize uncertainties. The selected regions are: (1) Northern Saudi Arabia and Jordan (area: 0.53×106 km2), (2) Southern Saudi Arabia, Qatar and United Arab Emiratis (area: 0.97×106 km2), (3) Yemen (area: 0.45×106 km2), and (4) Oman (area: 0.32×106 km2). Results indicate: (1) Northern Saudi Arabia and Jordan area is experiencing large depletions (-8.76±0.94 mm/yr; -4.68±0.50 km3/yr) in GRACE-derived terrestrial water storage (TWS) that is largely related to groundwater extraction as well as decrease in rainfall rates throughout the investigated period compared to the preceding period (average annual rainfall [AAR]: 2003-2013: 58 mm; 1979-2002: 103 mm), (2) Southern Saudi Arabia, Qatar and United Arab Emiratis area is experiencing a moderate depletion (-2.73±1.0 mm/yr; -2.63±0.96 km3/yr) in TWS that might be related to groundwater/oil extraction as well as a moderate decrease in rainfall rates (AAR: 2003-2013: 61 mm; 1979-2002: 82 mm), (3) Yemen is experiencing a slight depletion (-0.82±0.30 mm/yr; -0.36±0.13 km3/yr) in TWS that might be related groundwater extraction, and (4) Oman is experiencing slight increase (+0.78±0.30 mm/yr; +0.25±0.09 km3/yr) in TWS that might be related an increase in rainfall rates. Our preliminary results are being further examined by: (1) extracting temporal variations in groundwater storage by integrating GRACE-derived TWS and TWS outputs of bias-corrected land surface models (e.g., CLM4.5, GLDAS), and (2) comparisons of our findings with relevant independent datasets (e.g., extraction, discharge, and recharge rates).