Fig. 1: Context for water challenges in Egypt.

a Egyptian population [red line] and world population [black line] from 1 to 2020 C.E³. (Supplementary Table 1.4). b Qualitative comparison of stable Nile Flood heights from 641 to 1451 [black line – left axis]¹³ and decreasing modern yearly average discharge from Aswan Dam [red line – right axis] and flow at Dongola [blue line – right axis]^{16, 17} (Supplementary Tables 1.14 and 1.20). We note that the reader should not interpret a 1:1 correlation between the y-axes, and that the two separate groupings of data have been presented together to reflect that there has been little change in the Nile based on geologic survey¹⁵. c Gross Domestic Product (Constant 2010 $US) [black line] and GDP per Capita [red line] in Egypt⁶ (Supplementary Table 1.6). d Relative change in per capita food supply (kg/capita/year) relative to 1961 for meat [red line], cereals [black line], and pulses (beans, chickpeas, lentils) [blue line]. 1961 values for meat, cereal, and pulses are 10.71, 161.43, and 6.5 kg/capita/yr respectively⁷ (Supplementary Table 1.10).