Egypt's water budget deficit and suggested mitigation policies for the Grand Ethiopian Renaissance Dam filling scenarios

The scenarios incorporated in our analysis of the water budget deficit in Egypt include the impact of the GERD filling scenarios and the associated storage capacities, and are summarized as follows (table 1):

• (a)  
  Donia and Negm (2018) assumed three storage capacity scenarios: 74, 35, and 18.5 BCM and three filling period scenarios: 5, 10, and 20 years. The results indicated that with the five-year filling period of the GERD at a storage capacity of 74 BCM, the AHD reservoir will empty and will reach its minimum water level of 147 m by the fifth year.
• (b)  
  Keith et al (2017) examined seven filling rate strategies: retaining 100%, 50%, 25%, 20%, 15%, 10%, and 5% of the Blue Nile inflow. Their analysis showed that annual reservoir fill rates of 8%–15% can be beneficial for hydroelectric power generation for Ethiopia with a minimal effect on stream flow into Egypt assuming no significant impact of climate change until 2039. They also concluded that larger fill rates beyond the policy of 15% will have adverse impacts on the stream inflow. For example, with a 100% fill rate policy (equivalent to 2.5 years to reach full supply level (FSL)) will result in a 55% reduction of stream flow.
• (c)  
  King and Block (2014) examined five policies; three policies with impounding 5%, 10% or 25% of total monthly inflow, while the other two policies are conditional on exceeding the historical average streamflow (HASF) or 90% of the HASF. The results showed that the 5% filling policy will not significantly affect downstream flow but also will not help reaching the FSL of the reservoir. On the other hand, the 25% policy, can reduce the average downstream flows by more than 10 BCM per year.
• (d)  
  Liersch et al (2017) assumed three scenarios based on monthly minimal discharges to be released downstream: 75%, 50% and 25%. Each of these scenarios was simulated with three seepage rate assumptions (low, medium, and high), resulting in 18 filling scenarios considering climate change under wet and dry conditions. The results showed that with the release of Q₅₀ and Q₇₅ of average monthly discharge, the flows might be reduced by 10%–19% and 16%–44%, respectively, while releasing monthly Q₂₅ discharges will reduce only 5%–13% of the average monthly discharge to downstream countries and the FSL will be reached in eight years. The simulated evaporative losses during the filling process correspond to 6.5%–8.7% of average annual inflows while the seepage losses ranged between negligible to 24%–32% of inflows. The maximal seepage loss scenario is particularly highlighted in the present study.
• (e)  
  Omran and Negm (2018) indicated that in a scenario of filling the GERD in seven years, Egypt will face a significant shortage in water quantity associated with a reduction of 20% to 30% of electricity production from the AHD.
• (f)  
  Wheeler et al (2016) analyzed five different annual release scenarios: 25, 30, 35, 40, and 45 BCM yr⁻¹. The results indicated that reducing the risks to stream inflow into Egypt and energy generation can be achieved through combinations of agreed annual releases from the GERD as well as adopting a drought management policy for the AHD.
• (g)  
  Zhang et al (2015) considered five filling policies: impounding of 5, 10, and 25% of the Blue Nile inflow and retaining quantities greater than HASF or 90% of HASF with possible precipitation changes of −20, −10, −5, 0, +5, +10, +15, and +20% by the year 2060. The results showed that impounding 10% or 25% of monthly streamflow will result in a 6% or 14% average reduction in streamflow into Egypt during the first 5 years, respectively.
• (h)  
  Zhang et al (2016) proposed two scenarios with fractional impounding: 10 and 25% of inflow, one threshold filling strategy that allows any streamflow volume in excess of the HASF to be impounded in the reservoir and three absolute filling strategies: 4, 6, and 8 years. The results indicated that the 25%, 6 years and 8 years scenarios can provide the best scenarios for both upstream and downstream countries.

In order to assess the total water budget deficit, the best mitigation policies and the socio-economic impacts of each of the filling scenarios for the GERD, we use three methods that are summarized herein.

To constrain the ambiguity around the forecasts in Egypt's total water budget deficit during the suggested filling periods of the GERD, we use the estimates of the water budget deficit from the water budget model in Mazzoni et al (2018) and considering future population projections under the Shared Socioeconomic Pathways, Regional rivalry (SSP3) scenario. The SSP3 scenario is favorably selected because it incorporates the highest challenges towards mitigation and adaptation, with strong regional rivalry (Mazzoni et al 2018). Moreover, we implement the different filling scenarios in terms of time scales and retained volumes that we derive from a thorough literature review and collect the most recent analysis. Table 1 summarizes these different filling scenarios or strategies adopted by each study. We then derive the additional average annual water deficit for Egypt generated by the GERD filling and by the losses due to seepage and evaporation from Liersch et al (2017) and Wheeler et al (2020). A special emphasis is given to the water loss from the GERD due to seepage due to two reasons. First, the seepage losses have been largely underestimated in previous studies that dealt with evaluating the impact of the GERD and second, the seepage-related losses can reach annually up to 15 BCM compared to a much lesser annual evaporation-related losses of only 3.8 BCM (Liersch et al 2017).

In our analysis, we only select studies published on the topic in the last 5 years since some of the main technical specifications of the GERD have been publicly released only lately (such as the dam total capacity). Among all considered studies, different filling policies have been explored by either considering an a priori fixed number of years for the duration of the filling period, by using fractional retention rates of the total monthly stream flow entering in the reservoir that guarantees a permanent impoundment of water every month to fill-up the dam, or again by employing threshold-based policies, with retention rates conditional to a certain fixed value, which instead do not assure retention for storage in the years where the stream flow is lower than the selected baseline. To be able to compare the outcomes of the different studies we average their results across the climatic scenarios that they have considered in their analysis to match our use of the SSP3 one.

In table 2, we summarize what are all the most plausible proposed strategies that Egypt could undertake to mitigate the short-term and temporary effects of the GERD filling in terms of water deficit in particular: AHD Operation reduction (i.e. AHD rules to be readjusted to cope with the water reduction), groundwater extraction expansion, crop type selection, modernizing the irrigation system, changing fields canals to pipes, increasing wastewater reuse, rain harvesting, expanding desalination and reducing evaporation in lake Nasser. We then develop a corresponding feasibility index calculated through a first-order duration-cost-benefit analysis of the proposed mitigation strategies to obtain a parametric indicator that allows us to evaluate the practicability of each possible solution. The index is expressed as an inversely proportional function of the time required for implementing the strategy (i.e. hereafter is referred to as implementation swiftness) and its annual costs, and directly proportional to the benefits in terms of water volume in BCM yr⁻¹:

$$\begin{align*}{\text{Feasibility Index}}\; =\; & f\left( {\text{Duratio}}{{\text{n}}^{ - 1}},{\text{ Cost}}{{\text{s}}^{ - 1}}, \right.\\ & \times \quad \left. {\text{Benefits}} \right),\end{align*}$$

$$\begin{align*}{\text{Feasibility Index}}& = { }{\beta _D}{ }{\left( {\frac{1}{{{\text{Duration}}}}} \right)_{{\text{norm}}}}\\ & \quad + {\beta _C}{ }{\left( {\frac{1}{{{\text{Costs}}}}} \right)_{{\text{norm}}}}\\ & \quad + {\beta _B}{\text{ Benefit}}{{\text{s}}_{{\text{norm}}}}.\end{align*}$$

The three coefficients ${\beta _D}$, ${\beta _D}$, and ${\beta _D}$ are set equal to 1/3 to give the same weight to each variable. For the duration variable, we select five scenarios with their respective incremental abstract values: short term = 1, short-mid term = 2, mid term = 3, mid-long term = 4, and long term = 5. For the costs, we account for both the yearly expenditure due to the capital expense (CAPEX) costs depreciated over the lifetime span of the solution itself and the annual operating expense (OPEX) costs. We first derive a lower and upper bound for all the variables for each mitigation strategy, we then normalize each variable to a [0,1] interval, and we finally compute the overall feasibility index as a weighted sum of the three components. Given that there are different ranges and values for the costs and the implementation time of each measure, a range of values is given for the feasibility index of each mitigation strategy.

We use a simplified economic model to assess the impacts of the total water budget deficit under the different GERD's filling scenarios on the evolution of Egypt's agricultural GDP. This model presents a first-order analysis providing a lower limit estimate of the equivalent economic impact of the total water budget deficit on the agricultural sector due to loss in crop productivity arising from land degradation from lack of irrigation) and not accounting for the consequences on the industrial sector that are difficult to assess due to the lack of published records. The model (suppl. figure S1 available online at stacks.iop.org/ERL/16/074022/mmedia) uses average GDP growth rates projections from historical data for three cases: low (1.76%), medium (4.47%), or high (7.16%) growth rates from projections of Egypt's GDP (World Bank 2016). These projections represent the non-GERD GDP estimates. We then calculate the decrease in GDP for the 3, 5, 7, 10, and 21 years GERD filling scenarios. We finally calculate the GDP per capita using historical data and the population projections from the 2019 Revision of World Population Prospects (UN World Population Prospects 2019) for both the GERD and non-GERD cases. Yearly water budget loss and equivalent land loss are approximated using relationships from Mazzoni et al (2018) and Hamada (2017) respectively, where the loss of each 5 BCM would result in total degradation of ∼0.42 million hectares (sim1.2 million feddan). Egypt's total agricultural land area (∼9.1 million feddan equivalent to ∼3.822 million hectares) is valuated as Egypt's agricultural GDP to calculate the decrease in GDP due to total degradation often expressed in the local unit feddan (one Feddan is equal to 4200 m²). We also assess the increase in the unemployment due to land degradation in the agricultural sector (which employ a fourth of the work force in Egypt) using the average number of farmers per feddan from the Egyptian Ministry of Water Resources and Irrigation (MWRI 2014).

Figure 1 shows the resulting distribution of the outputs of each considered scenario in terms of years needed to fill the GERD and the expected annual total water budget deficit of Egyptian renewable freshwater supply by this process. Clearly, each selected filling rate will have different implications on the time to fill the reservoir and thus a proportional effect on the downstream flow reductions. As a result, we found that the estimated required time to fill up the GERD is distributed between a minimum of 2.5 and a maximum of 29.6 years, with a mean value of 10.86 (median: 9.19, Q1: 5.79, and Q3: 13.97 years). For more details on the effect on annual flows into Egypt, figure 2 summarizes in a box-plot format the statistical distribution of the resulting annual water deficit caused by the GERD filling, the seepage inferred from Liersch et al (2017), and the forecasted intrinsic Egyptian water budget gap derived from Mazzoni et al (2018). The main component of the overall water deficit for Egypt originates from the intrinsic water gap between the internal demand and the presently available renewable water supply. This difference, corresponding to 18.35 BCM yr⁻¹ in median value, is currently compensated by the reuse of drainage water within the Nile Delta and by unlawful withdrawal of deep groundwater (CAPMAS 2018). Both contribute to deteriorate the overall water quality (Mohie and Moussa 2016). It is worth mentioning that the above-mentioned amount of water deficit in Egypt does not include the annual groundwater recharge from Lake Nasser and northern Sudan to the Nubian Aquifer (Abdelmohsen et al 2019, Sultan et al 2013, Abdelmohsen et al 2020). It was estimated using a two-dimensional groundwater flow model that, at lake level of 178 meters above sea level (masl), the Nubian aquifer receives an annual recharge of 6 BCM yr⁻¹ compared to 0.7 BCM yr⁻¹, when the lake level drops to 170 masl. Collectively, the annual groundwater recharge from Lake Nasser and the northern Sudan basin can reach up to 8.5 BCM yr⁻¹ during periods of intensified precipitation on equatorial Africa (e.g. the period between 2012 and 2015; Abdelmohsen et al 2019). The amount of annual groundwater recharge from precipitation over the northern Sudan platform, which can be roughly estimated from the GRACE terrestrial water storage as 2.5 BCM yr⁻¹ (Abdelmohsen et al 2019), will not be affected by the construction of the GERD, yet the different scenarios for the GERD will consequently affect Lake Nasser levels and hence the annual recharge to the deep Nubian Aquifer will be significantly impeded. The response of the Nubian Aquifer to the different scenarios of the GERD filling should be investigated to estimate a reliable total water budget deficit in Egypt.

Zoom In Zoom Out Reset image size

Zoom In Zoom Out Reset image size

The other two components (i.e. water impounding during the filling period and seepage from the GERD), which are instead directly related to the construction of the GERD, collectively create an additional median water gap of ∼12.15 BCM yr⁻¹ considering all the expected lengths for the filling periods of the dam. The decrease in streamflow for Egypt due to the seepage losses in the GERD, not considering the outliers, could range from a minimum of 43 MCM yr⁻¹ to a maximum of 10.4 BCM yr⁻¹ (median: 2.5, Q1: 0.185, and Q3: 4.9 BCM yr⁻¹) assuming the total inflow to range between 43.2 and 53.3 BCM and seepage rates of 1% and 32% (Liersch et al 2017). However, for Egypt, the actual main reduction in the annual water supply is due to the filling itself of the upstream dam. The estimated loss, excluding outliers, ranges between 2.72 and 22.67 BCM yr⁻¹ (median: 9.64, Q1: 6.13, and Q3: 13.22 BCM yr⁻¹). In percentage, the effects of the GERD would create an additional increase of the present water deficit for Egypt between +34.4% and +98.7%, of which in average ∼83% is due to the filling and the remaining ∼17% to the seepage assuming a maximal seepage rate. If we account for all the components, Egypt may experience in the years of filling of the GERD a total annual water deficit from 24.7 to 36.5 BCM yr⁻¹ (distributed in percentage as: 32% due to GERD filling, 8% for seepage under GERD, and 60% of intrinsic water budget deficit), which corresponds to an average +35.5% of its current internal annual water demand. It is worth mentioning that these estimates represent the worst-case scenario, where no actions are taken from the Egyptian authorities to mitigate these expected rates of water deficits due to technical shortage or political instability. Additionally, enhanced flood events over the White Nile can positively impact the Egyptian water budget by introducing more than 25 BCM to Lake Nasser over a period of three years (e.g. the flooding event between 1999 and 2001; Bastawesy et al 2008).

Figure 3 shows the resulting feasibility of each proposed solution and the relative contribution of each mitigation strategy that we considered for computing the index that ranges from 0 (non feasible) to 1 (feasible). Inspection of the feasibility index estimations (figure 3) indicates that among all the proposed solutions to address the water budget deficit, the most practical option (feasibility index >50%) for Egypt in the short term would be to temporarily reduce or even completely suspend the operations at the AHD to partially offset the lower streamflow during the filling of the GERD. The loss in the Aswan basin reservoir can be recovered and distributed in the following years after the GERD starts operating when the main Nile streamflow will return to its regular rate. This would, of course, drastically reduce the electricity production from the Aswan hydropower plant (here accounted as cost for the proposed strategy) and to account for all the subsequent effects of this option. Other effective solutions include maximizing groundwater withdrawal (feasibility index >35%), although here we do not account for the environmental effects on degradation of fossil aquifers systems. However, this measure is highly cost effective compared to other measures (figure 3; table 2), yet the total production of current wells cannot bridge the GERD-induced water deficit gap with a total potential of 4.65 BCM yr⁻¹ (Omran and Negm 2018). This solution could be improved through the expansion of groundwater extraction from shallow aquifers east and west of the Nile Delta (Abotalib et al 2016, El-Saadawy et al 2020, Hegazy et al 2020, Khalil et al 2021). Furthermore, the largely unexplored fractured limestone aquifers east and west of the Nile Valley represent valuable corridors for expanding groundwater extraction due to: (1) the fractured and karstified nature of the aquifer that results in high groundwater yield of up to 1600 m³ d⁻¹ (Yousif et al 2018), (2) the abundant recharge from the deep Nubian aquifer through artesian upwelling along faults and thus naturally bringing deep water (up to 1500 m) to shallow levels (<600 m) at no cost (Hussein et al 2017, Abotalib and Heggy 2018; Abotalib et al 2019), and (3) the low water salinity for domestic and agricultural purposes (<3000 mg l⁻¹; Ibrahim and Lyons 2017, Yousif et al 2018). The feasibility index estimation also shows that changing the agriculture system toward the cultivation of crops that require less water could also be a feasible solution (feasibility index >20%). The current crop water use rate in Egypt is 1.4 m³ m⁻² yr⁻¹ (Mohie El Din and Moussa 2016) and thus 53.7 BCM of water every year is needed to irrigate the 9.1 million feddans. Replacement of the sugarcane with sugar beet and limitation of the rice cultivation to the official number of feddans (almost 1 million feddan, which is 850 000 feddan below the actual rice lands in Egypt 1.9 million feddan), the crop water use rate will be as low as 1 m³ m⁻² yr⁻¹ (Din et al 2016), which only requires 38.3 BCM to irrigate the 9.1 million feddans. Other options have a feasibility index lower than 10%, which means that they either require too much time for their implementation or the cost is too high, again resulting in a low efficacy in mitigating the water deficit. For example, modernizing the irrigation system is a costly and time-consuming process, where upgrading the irrigation systems of only 3140 ha in Upper Egypt costs up to 11.6 million US dollars (Takouleu 2020). The current irrigation system is a surface irrigation system (i.e. flood irrigation) that depends almost entirely on the AHD to regulate water through more than 29 000 km of canals and subcanals leading to the loss of more than 3 BCM of Nile water annually through evaporation in addition to the water shortage at canal tail end. These negative impacts of the surface irrigation encourage the Egyptian government to apply modern methods of irrigations such as sprinkler systems, drip irrigation and bubble irrigation (Abdelhafez et al 2020) as well as to line the irrigation canals (Khalil et al 2021).

Zoom In Zoom Out Reset image size

Growth rate GDP projections for agriculture and for total GDP per capita can be found in figures 4 and 5, respectively, considering the sum of the water losses in figure 2. In the years 2022, 2023 and 2024, our first order model suggests an equivalent agricultural GDP losses arising from the unmitigated total water budget deficit, for the total filling period, of ∼$51 billion for the 3 years filling scenario, ∼$28 billion for the 5 years filling scenario, ∼$17 billion for the 10 years filling scenario, and ∼$10 billion for the 21 year filling scenario. These economical losses reflect the degradation in crop production due to the unmitigated deficit in necessary irrigation water to maintain agricultural activities. The above reduces the existing cultivation area as explained in sections 2.4 and 3.2 and hence the associated agricultural GDP. The losses in the agricultural sector (i.e. Agricultural GDP) will decrease the total projected GDP per capita for Egypt for the years 2022, 2023 and 2024 from $ 2815, $ 2890 and $ 2968, for the case without the GERD, down to $ 2633, $ 2703 and $ 2777 when accounting only for the agricultural losses arising from the unmitigated total water budget deficit under the GERD short-term filling scenarios.

Zoom In Zoom Out Reset image size

Zoom In Zoom Out Reset image size

Unemployment projections for Egypt's agricultural sector are shown in figure 6 and the supplemental tables. Of Egypt's 28.8 million employed, about 5.5 million work in the agricultural sector (Central Agency for Public Mobilization and Statistics, (CAPMAS) 2018). Approximately each ∼1.4 feddan (0.6 ha) of agricultural land employ one person; hence the unmitigated total water budget deficit under the GERD proposed three-year short term filling scenario may degrade 2.8 million hectares of land, which would result in 4.75 million jobs losses in downstream in Egypt. This would result in an alarming loss of over three quarters of Egypt's agricultural land and resulting in more than 60% of agricultural workers unemployed. The total unemployment rate would rise from the current 11% to a future 25%.

Zoom In Zoom Out Reset image size

Our economic impacts model's accuracy is limited by a few key factors. Firstly, it does not account for time the Nile will need to restore full flow after GERD filling ends, and as a result, does not account for the economic effects in the years following the GERD's filling. The immediate upshoot in GDP during the year after the filling period ends is highly unlikely as many of the environmental and socioeconomic impacts could be irreversible. The 10 to 21 years filling scenarios, with the lowest net present value impact on Egypt's GDP, thus appears to be the best scenarios with long-term manageable economic impacts to a country that is already highly stressed by socio-economic instabilities and rapid increase in population. Secondly, the model hypothesizes that for every unit loss in the Nile River inflow, its distributaries will experience an equal unit loss of water. The downstream impacts such as land loss and available water for industrial and municipal use are more likely to be manifested as a non-linear decrease at a much higher rate for every unit decrease in the Nile itself. Furthermore, the model assumes that the distribution rates of water across agriculture, industry, and municipal use will remain unchanged. Lastly, these figures do not include the economical impacts on the growing food manufacturing and processing sector which contributed to ∼6% of Egypt's GDP in 2019 (USDA, 2020). Other service industries connected to industry and agriculture are likely to experience significant consequences because of decreased production capabilities. As such, the results on the equivalent decrease in the GDP per capita and the rise of unemployment should be considered as lower limits, the economic damage considering all the above factors will be higher.