Monitoring water storage decline over the Middle East

Water scarcity and environmental challenges are affecting many parts of the world, particularly the arid Middle East region. Limited water resources, urbanization, groundwater over-extraction, and water usage for irrigation and agriculture have exacerbated the situation over this region and is risking the future development of its growing population. This study investigates the changes in various water storage components including groundwater, surface water, and soil moisture in the Middle East. To this end, a long-term reanalysis of land-hydrologic water storage components was generated from 1980 to 2019 by combining multiple satellite remote sensing observations and a hydrological model via a state-of-art data assimilation approach. The results indicate that assimilating multivariate satellite remote sensing significantly improves the model performance. The reanalysis data also outperforms some of existing model outputs. Based on the results, a considerable water storage depletion is observed across the Middle East region, not only over the dryer parts but also in areas with above-average annual rainfall including countries located close to the Mediterranean Sea. The water depletion is most pronounced for groundwater and over arid and semiarid areas in the central to southern parts involving Iran, Saudi Arabia, Bahrain, and the United Arab Emirates. Water storage decline is further found in the region's eastern, north-western, and western parts. The results also reveal a close link between water storage declines and other environmental factors such as dust storms and loss of vegetation canopies.