Satellite-based estimates of groundwater storage depletion over Egypt

Abstract

An arid climate accompanied by a freshwater shortage plagued Egypt. It has resorted to groundwater reserves to meet the increasing water demands. Fossil aquifers were lately adopted as the sole water source to provide the irrigation water requirements of the ongoing reclamation activities in barren areas. Yet, the scarcity of measurements regarding the changes in the aquifers’ storage poses a great challenge to such sustainable resource management. In this context, the Gravity Recovery and Climate Experiment (GRACE) mission enables a novel consistent approach to deriving aquifers’ storage changes. In this study, the GRACE monthly solutions during the period 2003–2021 were utilized to estimate alterations in terrestrial water storage (TWS) throughout Egypt. Changes in groundwater storage (GWS) were inferred by subtracting soil water content, derived from the GLDAS-NOAH hydrological model, from the retrieved TWS. The secular trends in TWS and GWS were obtained using the linear least square method, while the non-parametric technique (Mann–Kendall’s tau) was applied to check the trend significance. The derived changes in GWS showed that all aquifers are undergoing a significant loss rate in their storage. The average depletion rate over the Sinai Peninsula was estimated at 0.64 ± 0.03 cm/year, while the depletion rate over the Nile delta aquifer was 0.32 ± 0.03 cm/year. During the investigated period (2003–2021), the extracted groundwater quantity from the Nubian aquifer in the Western Desert is estimated at nearly 7.25 km3. The storage loss from the Moghra aquifer has significantly increased from 32 Mm3/year (2003–2009) to 262 Mm3/year (2015–2021). This reflects the aquifer exposure for extensive water pumping to irrigate newly cultivated lands. The derived findings on the aquifers’ storage losses provide a vital source of information for the decision-makers to be employed for short- and long-term groundwater management.

Modelling Approach for Assessment of Groundwater Potential of the Moghra Aquifer, Egypt, for Extensive Rural Development

“…The cultivation project is well underway in the area. As deduced by the analysis of Gravity Recovery and Climate Experiment (GRACE) satellite mission-derived groundwater storage (GWS), the GWS within the development area is currently overexploited, a fact that bears adverse impacts on the whole aquifer extent [32]. The Moghra aquifer is the main water-bearing formation, covering the majority of the study area [33].…”

“…GRACE was also employed to estimate groundwater storage coefficients, including the storativity or specific yield (S y ), as appropriate [59,60]. The time series that represents the change in terrestrial water storage (∆TWS) was extracted from the recently released gridded GRACE dataset provided by the three processing centres (i.e., GRACE's science data centres) [32]. This dataset consists of a temporal monthly TWS anomaly, a mass deviation from the baseline, which is expressed in terms of equivalent water height (EWH) and posted on a 1 • grid resolution (PODAAC website at https://grace.jpl.nasa.gov/data/get-data/monthly-mass-grids-land; accessed on 1 March 2023).…”

Assessment of groundwater suitability for different activities in Toshka district, south Egypt

“…In Egypt, a recent mega groundwater-dependent development project has been proposed within a national framework, aiming to bridge the impending food gap. The Egyptian government has set ambitious plans to reclaim vast stretches of barren land in the Western Desert, seeking to alleviate the overpopulation along the Nile River (Shalby et al 2023). The success of development in the Western Desert in Egypt hinges largely on the Nubian Sandstone Aquifer (NSA) (Aly et al 2019).…”

Integrated Management and Environmental Impact Assessment of Sustainable Groundwater-Dependent Development in Toshka District, Egypt

“…The development activities aim to establish integrated communities in such barren lands to relieve the overpopulated pressure in the Nile Valley and Delta [11,12]. Agribusiness in the western desert is regarded as one of the main development axes of Egypt's strategic plan [13,14]. The Nubian Sandstone Aquifer (NSA) was considered a lifeline for the proposed rural communities in such remote areas [7].…”