Reply to Comment on ‘Egypt’s water budget deficit and suggested mitigation policies for the Grand Ethiopian Renaissance Dam filling scenarios’ by Kevin Wheeler et al’

We thank Wheeler et al for positively confirming our results’ reproducibility; however, we show herein that their critique misrepresents the aim, approach, and interpretations reported in Heggy et al (2021 Environ. Res. Lett. 16 074022), which remain valid. The reply herein demonstrates that Wheeler et al incorrectly interpreted Heggy et al’s (2021 Environ. Res. Lett. 16 074022) estimates of the median unmitigated total water budget deficit for Egypt of 31 BCM yr⁻¹ to be entirely caused by GERD. The comment overlooks the fact that this estimated value is the sum of Egypt’s existing intrinsic deficit (18.5 BCM yr⁻¹), the initial reservoir seepage (2.5 BCM yr⁻¹), and the median dam impoundment (9.5 BCM yr⁻¹) under different GERD filling scenarios ranging from 2.5 to 29.6 years as shown in figure 2 and section 3.1 in Heggy et al (2021 Environ. Res. Lett. 16 074022). Consequently, our evaluation of the deficit was mistakenly deemed exaggerated as well as the socioeconomic impacts that rely on its estimate. These misinterpretations led to inappropriate comparisons between the results of the unmitigated total water budget deficit under the shortest filling scenario in Heggy et al (2021 Environ. Res. Lett. 16 074022) with longer ones from other studies that focus exclusively on GERD impoundment and assess the economic impacts of water shortage after applying several suggested mitigations that are not yet formally agreed upon, implemented, or budgeted. Instead, Heggy et al (2021 Environ. Res. Lett. 16 074022) provided a holistic evaluation of the current status of the total water budget deficit in Egypt (including intrinsic and GERD components) and its equivalent economic representation to support decision-makers in better implementing the fourth statement of the declaration of principles between the Nile’s riparian countries. The suggestion that the results of the unmitigated scenarios in Heggy et al (2021 Environ. Res. Lett. 16 074022) should match those of the mitigated ones cited in Wheeler et al is erroneous from both hydrological and policy perspectives.