For millennia, the Nile River provided Egypt with abundant water. However, rapid population growth (2.1% annually from 1989-2018) and economic expansion (4.4% annual GDP growth from 1989-2018) have significantly increased water demand. Dietary shifts, particularly increased consumption of animal products, have further exacerbated the situation. In 2017, Egypt's renewable water resources per capita (628 m³/yr) fell below the water scarcity threshold defined by the Falkenmark Index. This study aims to quantitatively detail the changes in water demand and use over six decades, providing a basis for projecting future demand and proposing solutions for more efficient water use. While previous research offered snapshots of water use and virtual water trade, this study provides a more detailed, year-by-year reconstruction, down to the individual crop level, improving understanding of the driving factors and enabling more accurate future projections based on empirical demand relationships. This detailed analysis facilitates the identification of opportunities for water saving, reuse, and improved overall efficiency.

The authors acknowledge previous work, including governmental literature, which presented snapshots of water use and virtual water trade in Egypt. However, this study differentiates itself through its detailed year-by-year reconstruction of water use trends at the individual crop level. The improved understanding of factors driving these trends and the utilization of this context to project future water demand based on empirical demand relationships represent key innovations. The paper also references studies on water footprint accounting for agriculture at global and regional scales, which support the methodological approach used in this research.

The study employs a bottom-up, crop-based analysis of agricultural water use, integrating extensive datasets from the Food and Agriculture Organization of the United Nations (FAO), the World Bank, and the United Nations Population Division. The analysis focuses on major water-consuming crops, including cereals, fruits, vegetables, and various industrial crops. Production, import, and export data are utilized to quantify water demand. The concept of virtual water, the amount of water embedded in traded goods, is crucial in assessing the total water demand met through imports. An empirical model is developed to relate water demand to population and economic growth rates, allowing for projections of future water demand under different scenarios. Irrigation application efficiency, calculated using proportions of irrigation types and their associated efficiencies, is accounted for to refine the estimations of water consumption. The model incorporates several assumptions, including the assumption that all additional demand will be met through imports as Egypt is already operating at its in-country production limit. The model also accounts for policy-driven changes in demand for specific crops, keeping their per capita demand constant while acknowledging that population growth still results in an increase in their total tonnage demand. Blue water numbers are employed to quantify water consumption for crops, acknowledging that the study focuses on irrigated water from the Nile.

The analysis reveals that Egypt began fully utilizing available local water resources in the late 1970s. Since then, the nation has met the increasing water demand through a combination of increased virtual water imports and improved water reuse. The authors' bottom-up reconstruction of historical water use shows that Egypt's direct consumption of Nile water averaged roughly 61.5 km³/year from 1988 to 2017, exceeding the share allocated by the 1959 Nile Agreement with Sudan. This surplus is attributed to unconsumed water from Sudan and increases in Nile flow. Virtual water imports significantly contributed to meeting the increased water demand, reaching 40 km³ in the 2010s. Projections based on the empirical model indicate that, under nominal scenarios of population and economic growth (similar to the past 30 years), Egypt will import more virtual water than the average Nile water use within this decade. By 2030, significant increases in virtual water imports are projected across most population and economic growth scenarios. A nominal scenario with GDP per capita growth matching the 1988-2017 average (2.3%) and population growth matching the UN Medium Variant projection in 2035 (1.7%) shows a substantial increase in virtual water imports, driven by compounding population and economic growth, further increasing per capita consumption. The model also provides a hindcast, closely aligning with the sum of in-country Nile water use and virtual water imports, further validating the model's accuracy. The study emphasizes the importance of improving irrigation application efficiency to bend the demand curve downwards.

The findings highlight the critical water scarcity situation in Egypt and the need for continued and strengthened adaptations to rising water demand. The authors suggest that strategies focusing on agricultural productivity improvements should acknowledge the limited resource of water by implementing a robust water pricing system. Smart management of agricultural export and import portfolios can leverage Egypt's high agricultural yields by exporting high-value, water-efficient crops and importing lower-value, less efficient crops. Inter-basin connectivity becomes crucial for importing water-intensive products like meat and allocating water resources more efficiently. Reducing population growth rates through methods like healthcare expansion and education is identified as crucial for mitigating water scarcity. However, no single solution suffices, as increased industrial demand due to economic growth and diversification and increased municipal demand due to tourism and urbanization add further pressure. The impact of the Grand Ethiopian Renaissance Dam (GERD) is acknowledged as a potential additional stressor, along with the effects of climate change. Climate change is projected to increase Nile interannual variability and heighten the need for storage, as well as exacerbate the effects of sea-level rise, saltwater intrusion, and increased temperatures affecting agricultural productivity and evaporation.

The research concludes that while Egypt's relationship with the Nile remains crucial, the level of dependence is shifting. In the near future, Egypt will rely on external virtual water to the same extent as the Nile, requiring policy adaptations. The study emphasizes the need for optimal management of internal water demand, international cooperation with neighboring countries, and the importance of Egypt serving as a model for water-scarce nations and a leader in the Nile Basin. Failure to make necessary changes will have severe ecological consequences for the entire region.

The study acknowledges that water use data for Egypt suffers from inconsistencies and limited availability across different sources and time periods. The analysis depends on the accuracy of various data inputs, including agricultural statistics, water requirement estimates, and irrigation application efficiency figures, which introduce a level of uncertainty. Furthermore, the study does not explicitly model the impacts of climate change, which could alter future water availability and demand.