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The countries within the Nile Basin have become increasingly water stressed with each passing year due to the intensification of climate change, and disagreements about water allocation rights between these countries only exacerbate the issue. For about a century, Ethiopia and Egypt have been quarrelling over rights to the Nile’s waters with no resolution in sight. In 2011, Ethiopia began construction of the Grand Ethiopian Renaissance Dam (GERD), which increased tensions. As of 2023, the dam’s construction was completed but negotiations have made no meaningful progress. The dam worsens political relations but impacts the environment, economy, and society in both positive and negative ways. Considering these impacts and the example of the demolition of the Klamath River dams, it was determined that dam demolition would be the most beneficial and equitable course of action, in the long run, for all the Nile River riparian countries. A policy memo was then constructed advocating for demolition of the GERD.

Transboundary waters account for a significant portion of global freshwater resources, yet their management is often challenging. The Nile River basin faces significant challenges owing to the complex history and unique context of the basin. Examining the experience of other transboundary basins can offer insights for the effective management of the Nile waters. This paper aims to extract contextual lessons for the Nile from global transboundary water management practices. To that end, we performed a scoping literature search to identify well-researched transboundary water management practices from across the world, selected key case studies, and analyzed their management practices. We discussed the context of the Nile and organized the unique challenges of the basin in five themes, and we discussed how global experiences could provide valuable insights for the Nile basin within each theme. Trust building, the need for equitable water use frameworks, a strong river basin organization, the nuanced role of external actors, and the impact of broader political context were major themes that emerged from the analysis of the Nile context. Within each theme, we presented experiences from multiple basins to inform transboundary water management in the Nile basin. [ABSTRACT FROM AUTHOR]

Climate change and its variability impact water availability in wetlands, jeopardizing their ecosystems. This study focuses on the Sudd Wetland, Africa’s most extensive and one of the world’s largest tropical wetland systems. We analyzed historical climate data (temperature, rainfall) in the Sudd and its upstream regions to assess climate impacts on the wetland’s health (NDVI) and water conditions (surface water extent, lake height) using spatial and temporal trends. The study unveils distinct seasonal and long-term variations in vegetation and temporal fluctuations in surface water dynamics within the Sudd Wetland. While central areas experienced declining NDVI (vegetation cover), peripheries showed an increase. The wetland gained open water surface area, with a slight rise in permanent water (3%) and a significant increase in seasonal inundations (19%). All monitored water bodies in the Sudd displayed a gradual increase in surface water height. Climate shifts are observed as rising temperatures and increased rainfall trends. Annual and seasonal temperatures rose across the basin, with the January-Feburary season experiencing the most significant increase (~ 1.3 °C). Rainfall trends were mostly flat, except for the south-central and southeastern regions, where a statistically significant increase ranging from 5 mm to 17 mm per year was observed. Conclusive evidence from this paper could be used to assess water policy and management in the region while protecting key parts of the hydrologic cycle. [ABSTRACT FROM AUTHOR]

This study utilized the machine learning algorithm called "Bagging" to gain a better understanding of the relationships between climate variability, crop yields, and the agricultural contributions to the gross domestic product (agrigdp) in the Nile basin. The multiple stepwise regression model (MSRM) was also used as a comparison. The time series data collected from 1961 to 2016 for four main crops (groundnuts, sorghum, wheat, and sugarcane), rainfall, air temperature (minimum, mean, and maximum), and agrigdp were divided into 70% for training and 30% for testing using R packages. The results indicated that the Bagging algorithm improved crop yield predictions by 18%—63% compared to the MSRM. All crops demonstrated a greater sensitivity to climate variability, resulting in a low probability of achieving the highest attainable crop yield: 18% – 33% for groundnut, 18%—38% for sorghum, 21%—41% for wheat, and 22%—56% for sugarcane. The climate variability also led to a basin-wide loss of 35 million US$ in the agrigdp, with a basin-wide probability of 29%—61% for attaining the highest agrigdp. The algorithm clearly identified the ideal climatic conditions for reaching the highest attainable crop yields and agrigdp in the Nile Basin. The central factor was found to be air temperature, particularly the mean temperature, with anomalies of ± 0.5 °C responsible for 17%—69% of crop yield losses. Strategies for adapting to and managing risks associated with climate variability should focus on on-farm air temperature management practices, technologies such as greenhouses, and plant breeding. [ABSTRACT FROM AUTHOR]

Transboundary waters account for a significant portion of global freshwater resources, yet their management is often challenging. The Nile River basin faces significant challenges owing to the complex history and unique context of the basin. Examining the experience of other transboundary basins can offer insights for the effective management of the Nile waters. This paper aims to extract contextual lessons for the Nile from global transboundary water management practices. To that end, we performed a scoping literature search to identify well-researched transboundary water management practices from across the world, selected key case studies, and analyzed their management practices. We discussed the context of the Nile and organized the unique challenges of the basin in five themes, and we discussed how global experiences could provide valuable insights for the Nile basin within each theme. Trust building, the need for equitable water use frameworks, a strong river basin organization, the nuanced role of external actors, and the impact of broader political context were major themes that emerged from the analysis of the Nile context. Within each theme, we presented experiences from multiple basins to inform transboundary water management in the Nile basin.

Hydrological modeling is important to provide relevant hydrologic information from limited data. In this study, Hydrologic Modeling System (HEC-HMS) was used to simulate the rainfall–runoff relationship for the Dabus subbasin of the Blue Nile Basin. Daily precipitation and stream flow data from 2002 to 2019 were used as key input data for the model, together with soil and land use/land cover data, and a digital elevation model of the study area. Arc-GIS was employed in combination with Arc Hydro and HEC-GeoHMS tools for terrain processing and translating spatial information into model files for HEC-HMS, respectively. Model calibration was done with data from 2002 to 2014, while the validation was done from 2015 to 2019. Nash-Sutcliffe simulation efficiency (NSE), observation standardized ratio (RSR), and coefficient of correlation (R2) were used to assess the performance of the model. With NSE, RSR, and R2 values of 0.784, 0.334, and 0.816 for calibration, and 0.793, 0.323, and 0.875 for validation, the model simulation of stream flows was found in good agreement with the observed values. Therefore, the HEC-HMS model can be utilized to predict stream flows in ungauged catchments in the Dabus subbasin from measured rainfall data for proper water resource planning and management. HIGHLIGHTS Rainfall–runoff relationship for data-scarce subbasin in the Blue Nile Basin was developed using HEC-HMS hydrological model.; Arc-GIS was combined with ARC hydro and HEC-GEoHMS tools for terrain and basin processing to provide suitable inputs to the HEC-HMS model.; The HEC-HMS hydrological model to simulate stream flow from rainfall data for the ungauged catchments in the subbasin is reliable and acceptable.;

Climate change poses a fundamental threat to agriculture within the Nile basin due to the magnitude of projected impacts and low adaptive capacity. So far, climate change impacts on agriculture for the basin have mostly been assessed for single-cropping systems, which may bias the results considering that the basin is dominated by different cropping systems, with about one-third of the crop area under double cropping. In this study, we simulate single- and double-cropping systems in the Nile basin and assess the climate change impacts on different cropping systems under two scenarios, i.e. “no adaptation” and “adaptation to a late-maturing cultivar”. We find that the mean crop yields of maize, soybean and wheat decrease with future warming without cultivar adaptation. We attribute this to the shortening of the growing season due to increased temperature. The decrease is stronger in all single-cropping systems (12.6–45.5%) than in double-cropping systems (5.9–26.6%). The relative magnitude of yield reduction varies spatially with the greatest reduction in the northern part of the basin experiencing the strongest warming. In a scenario with cultivar adaptation, mean crop yields show a stronger increase in double-cropping systems (14.4–35.2%) than single-cropping systems (8.3–13.7%). In this scenario, farmers could possibly benefit from increasing cropping intensities while adapting to late-maturing cultivars. This study underscores the importance of accounting for multiple-cropping systems in agricultural assessments under climate change within the Nile basin. [ABSTRACT FROM AUTHOR]

An accurate crop yield forecast at a reasonable cost is required for increasing production and securing food. Therefore, spectral reflectance was measured with a spectroradiometer (k 350-2500 nm) to predict grain yield (GY) and aboveground biomass yield (ABY) of teff and finger millet in Ethiopia. We calculated six spectral vegetation indices (SVIs): enhanced vegetation index (EVI), normalized difference VI (NDVI), soil-adjusted VI (SAVI), green (GNDVI), green chlorophyll VI (GCVI), and simple ratio (SR). Linear regression models fitted validation data with coefficient of determination (R2 ) of 0.73, and root mean square error (RMSE) of 0.11 for teff GY, R2 of 0.45 and RMSE of 0.52 for teff ABY, R2 of 0.92 and RMSE of 0.22 for finger millet GY, and R2 of 0.90 and RMSE of 0.24 for finger millet ABY. The study demonstrates the potential of spectroradiometer-derived SVIs to predict finger millet and teff production in the catchment. [ABSTRACT FROM AUTHOR]

The effect of a policy intervention is estimated as the difference between a state of the world without the intervention – the dynamic baseline – and with the intervention. Negotiations on managing transboundary water resources confront three kinds of problems in specifying the dynamic baseline: unexamined baselines, uncertain baselines and contested baselines. This paper focuses on contested baselines. Controversy may arise from different ethical or political assessments of the appropriate choice of the state of the world without the policy intervention. The Grand Ethiopian Renaissance Dam on the Nile highlights the importance of understanding contested baselines involving transboundary water resources. [ABSTRACT FROM AUTHOR]

Study region: Nile basin. Study focus: Several studies have shown a relationship between climate change and changes in sediment yield. However, there are limited modeling applications that study this relationship at regional scales mainly due to data availability and computational cost. This study proposes a methodological framework using the SWAT+ model to predict and project sediment yield at a regional scale in data-scarce regions using global datasets. We implement a framework that (a) incorporates topographic factors from high/medium resolution DEMs (b) incorporates crop phenology data (c) introduces an areal threshold to linearize sediment yield in large model units and (d) apply a hydrological mass balance calibration. We test this methodology in the Nile Basin using a model application with (revised) and without (default) the framework under historical and future climate projections. New hydrological insights for the region: Results show improved sediment yield estimates in the revised model, both in absolute values and spatial distribution when compared to measured and reported estimates. The contemporary long term (1989 – 2019) annual mean sediment yield in the revised model was 1.79 t ha−1 yr−1 and projected to increase by 61 % (44 % more than the default estimates) in the future period (2071 – 2100), with the greatest sediment yield increase in the eastern part of the basin. Thus, the proposed framework improves and influences modeled and predicted sediment yield respectively.

Degradation of crop and grazing lands is a pervasive problem that negatively impacts agricultural productivity and livelihoods of crop-livestock farmers in the Blue Nile basin of Ethiopia. Area enclosure together with a cut and carry livestock feeding system is often advocated as an approach for the regeneration of degraded grazing lands. This paper reports the results of a two-year farmer participatory study conducted to assess the effects of infiltration trenches (ITs) and Chloris gayana Kunth (Rhodes grass; cultivar Masaba; tetraploid; C4 grass species) reseeding on restoration of degraded grazing lands. A split plot design was used with IT as the main plot and C. gayana reseeding as a sub-plot on 28 private grazing plots under enclosure. The results showed that IT alone increased soil moisture content and prolonged the growing period. IT and C. gayana reseeding together significantly (P ≤ 0.05) increased herbage dry matter yield and improved soil chemical properties. The highest mean herbage dry matter yield (21 Mg ha−1 per cut) was recorded for plots treated with IT and reseeded with C. gayana. The higher herbage dry matter yield was attributed to increased soil moisture and the resultant prolonged growing period induced by the trenches coupled with the ability of C. gayana to effectively utilize the retained water. The results suggest that an integrated land management approach involving enclosure, in-situ water conservation and C. gayana reseeding can rapidly increase biomass productivity on degraded grazing lands while also enhancing soil quality with concomitant livelihood benefits for farmers. [ABSTRACT FROM AUTHOR]

This paper deals with the dispute between Egypt and Ethiopia over the legality of the construction of the Grand Ethiopian Renaissance Dam on the Blue Nile river and the legal principles of international law of watercourses as applicable to the dam which may be applied to resolve the dispute peacefully. [ABSTRACT FROM AUTHOR]

It is not shortage or lack of water that leads to conflict but the way how water is governed and managed. It is said that water will be, much more than oil, the major geopolitical issue of the 21st century. Although it is difficult to demonstrate this, it is clear that the increasing scarcity of the resource, on the one hand, and the configuration of its availability, on the other, are conflict-generating. In the particular case of the African continent, the large catchment basins of the Nile, Niger and Chad, shared by many states of unequal power, are the scene of inefficient hydro-diplomacy. Indeed, north to south, the Nile Delta is 161 km long and covers the coastline of Egypt from Alexandria in the west to Port Said in the east. Egypt with 100 mln population is de facto the principal hydro-hegemon state in the Nile basin. Nevertheless, a couple of riparian states, as Ethiopia (105 mln population), have taken measures in order to challenge this status quo: the signature and launching of the Nile Basin Initiative (NBI), the signature of Cooperative Framework Agreement (CFA), the construction of the Grand Ethiopian Renaissance Dam (GERD) and the signing of the Declaration of Principles Agreement. The article attempts to analyse the urgency of the problem of water resources allocation in Africa with particular focus to the Nile basin and the complexity of agreements regulating the issue dating back to the colonial era. The study also emphasizes the difficulties bilateral and multilateral aids faced while trying to solve a conflict. As Nile for many states is not just a source of water, it is the host of a fragile ecosystem, essential for maintaining the environmental and ecological balance of North-East Africa.

The objective of this study is to trace the historical evolution of the present Nile Basin regulatory framework and examine its influence on the current interactions among Nile riparian states. This research adopts a case-study design, with in-depth qualitative analysis of the Nile Basin as an example of the complex transboundary relations over shared waters. It uses an analytical framework derived from the New Institutional Economics (NIE) to analyse the evolution of the institutional framework that has governed the Nile basin and how it affected the annual water share allocated to each riparian country. The study argues that the historical beliefs and social norms of the riparian societies have been among the major factors that influenced the cooperation attempts during the past century and determined their outcomes. Therefore, a prerequisite to develop sustainable cooperation is levelling the playing field by addressing the beliefs and norms that have prevented cooperation while identifying the beliefs that can support cooperation. [ABSTRACT FROM AUTHOR]

The construction of the Grand Ethiopian Renaissance Dam (GERD) on the Nile River has triggered much debate between Ethiopia, Sudan, and Egypt on the dam's effects. Once completed, the GERD will be Africa's largest hydropower plant. This study analyzes the implications of cooperative long‐term operation of the GERD for Nile riverine flooding downstream of the dam. A daily river system model of the Eastern Nile is developed and used to examine how cooperative long‐term operation of the GERD would affect the occurrence of three flood alarm levels (alert, critical, and flooding) in Sudan downstream of the dam. A reconnaissance‐level flood inundation model is developed for the Nile within Khartoum State (Sudan's capital) to assess the GERD's impacts on the flood extent in the state based on simulated flows from the river system model. Assuming the GERD is operated to achieve a 90% power reliability and active upstream‐downstream data sharing between Ethiopia and Sudan on the dam's daily outflows, results show that the GERD would reduce the occurrence of the three alarm levels. Based on 34 simulated river flow sequences, the proportion of years with at least one flooding alarm day at Khartoum Gage declined from 37% without the GERD to 11% with the GERD. Seasonal coordination and planning between Ethiopia and Sudan are necessary to mitigate the remaining riverine flood hazard. Although cooperative long‐term operation of the GERD could play a positive role in reducing the riverine flood hazard in Sudan, the associated river flow alterations would adversely impact recession agriculture and the environment. [ABSTRACT FROM AUTHOR]

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When it comes to conflicts over the allocation of freshwater supply, who bears the burden, at what cost, and at what scale are important questions. While science can contribute to resolution of certain water allocation disputes, more scientific certainty will not resolve most water allocation controversies. Water stress in Africa and in the Middle East—particularly in the Nile Basin—is likely to lead to a range of conflicts, not because there is not enough scientific information to go around, but for other reasons. Water stress is likely to emerge as an increasingly important concern because population growth, current allocation practices, unchecked demand, and underinvestment in infrastructure are not being appropriately addressed. An effective way to resolve water crisis is to reframe conflicting needs and uses of water as opportunities for joint decision-making about this shared resource. The authors use the Nile Basin to illustrate how such informal problem-solving and decision-making can be initiated. [ABSTRACT FROM PUBLISHER]

Abstract Compound extremes—particularly hot and dry years—can reduce crop yields and result in acute water scarcity. These risks are particularly pronounced in the Upper Nile Basin, a chronically water stressed agricultural region that includes western Ethiopia, South Sudan, and Uganda. While the causes of humanitarian crises in the Nile Basin are complex and involve governance, conflict, and climate, we demonstrate that nearly all recent regional crop failures have occurred amid hot and dry conditions and low runoff supplies. Using an observational ensemble, we find that such hot and dry years have been more frequent in recent decades, driven by increasing regional temperatures. This trend is likely to continue despite climate model projections of increasing regional precipitation. By the late 21st century, the frequency of hot and dry years may rise by a factor of 1.5–3, even if warming is limited to 2 °C. Regional water scarcity will continue to be a chronic issue for the Upper Nile from population growth alone, but runoff deficits during future hot and dry years will amplify this effect, leaving an additional 5–15% of the future population facing water scarcity. Climate change, along with the region's complex water politics, dependence on subsistence agriculture, and history of geopolitical instability, places the region at risk of severe food and water shortages as hot and dry years become more frequent. Adaptation and climate‐resilient water management policies informed by an understanding of compound extremes will be essential to manage these risks.

The importance of cooperation on transboundary waters is stated as a target in the United Nations 2030 Agenda for Sustainable Development Goals (SDG6: water). Cooperation on transboundary water management is critical, particularly because it concerns issues across multiple states, SDGs and targets regarding agriculture, energy, ecosystems, climate adaptation, health, and peace and security. The percentage of transboundary basin area within a country that has an “operational arrangement” for water cooperation is used as the main indicator of such cooperation in the SDGs for “equitable and reasonable use“ of water resources (SDG 6.5.2). However, no clear criteria and explanation are available for what exactly constitutes an “equitable and reasonable use” in any such “operational arrangements.” Furthermore, it is understandable that any such arrangements may be shaped by differences in historical, legal, and political contexts and hence may be inherently unjust. Here, we highlight the limitations of SDG indicators, particularly SDG 6.5.2, to monitor equity of resource sharing in transboundary river systems. Using Walzer’s theory of morality of the state and cosmopolitanism as a framework, we examine the Nile basin as a case study to demonstrate the shortcomings of current SDG criteria and indicators. Our article contributes ideas of “operationalizing” theoretical justice toward a more equitable water management in transboundary rivers.

This study examines management approaches for hydropower generation and irrigation and domestic water supply for the Tekeze-Atbara, a transboundary river between Ethiopia, Eritrea and Sudan, in above- and below-normal hydrologic conditions, considering current and future water demand scenarios. Satellite data are used to substitute for unavailable or inaccessible ground meteorological and dam data. Based on three examined coordination scenarios, the analysis finds that coordinating the management of the Sudanese dams would bring significant benefits to water supply and energy generation. An optimization analysis is necessary to reveal the full value of coordination of dams in the Tekeze-Atbara Basin. [ABSTRACT FROM AUTHOR]

Water-related conflict chronology can be grouped around two broad sets of ideas: On the one hand is material-related conflict such as water stress and under-development; while on the other is management-related conflict including state-failure and lack of governance. In line with the latter form of conflict, this paper gives a specific consideration to the three types of causal factors looming with the potential for conflict over the Nile basin: Political tensions among stakeholders, lack of all-inclusive agreement on management of the Nile water, and states' unilateral actions. By identifying these causal factors, this study limits itself to focus on the initial phase of conflict resolutions, that is diagnosing sources to select some aspects of perceived reality and make them more salient in the methodological context. Based on Johan Galtung's theoretical approaches on conflict dynamics, the paper explores two areas that are lacking in current literature. It accounts for the sources of conflict over the Nile basin hinging on three variables, while mapping the nature of the on-going negotiation process around Ethiopia's "Grand Ethiopian Renaissance Dam" construction. This process is distributive in form and offers a collaborative (win-win) form of negotiations to cement the latter and to redress current predicaments. [ABSTRACT FROM AUTHOR]

The Grand Ethiopian Renaissance Dam (GERD) filling and operation is a highly sensitive issue for Egypt and Sudan. A recently accepted manuscript by Heggy et al (2021 Environ. Res. Lett. 16 074022) assessed the water deficit for Egypt based on different scenarios for the first filling of GERD lake and estimated 31 billion cubic meters per year under a 3 year filling scenario. We would like to present grossly mischaracterized assumptions, inaccurate data, and controversial conclusions found in this accepted manuscript through this rebuttal. Although the accepted manuscript does not include any new analysis of the River Nile Hydrology, the results of previous substantive studies were misinterpreted or ignored. Moreover, we have serious concerns about the basic hydrological assumptions that are the basis for the economic impacts and the potential loss of the Egyptian agricultural lands. The main methodological flaws of concerns are (a) how the deficit is calculated, losses from GERD, especially the evaporation losses that contradicts several previous studies (e.g. Wheeler et al 2016 Water Int. 41 611–34; Eldardiry and Hossain 2020 J. Hydrol. 125708; Wheeler et al 2020 Nat. Commun. 11 1–9); (b) neglecting the normal role of High Aswan Dam (HAD) reservoir and directly linking the deficit of the water budget to an immediate loss of agricultural lands with all other associated exaggerated economic impacts estimates; (c) including highly exaggerated seepage losses from the GERD lake; (d) neglecting the updated situation of Aswan High Dam reservoir levels and the GERD’s infrastructure itself, and (e) quantifying the impacts of potential changes of water level on HAD reservoir on the Nubian aquifer. We herein present a direct fact-checking approach including the studies cited in the accepted manuscript. We believe that this critical comment paper can serve as a basis for defending scientific integrity and contributes to cooperation and peace in the region.

Achieving a water, food, and energy (WFE) nexus balance through policy interventions is challenging in a transboundary river basin because of the dynamic nature and intersectoral complexity that may cross borders. The Nile basin is shared by a number of riparian countries and is currently experiencing rapid population and economic growth. This has sparked new developments to meet the growing water, food, and energy demands, alleviate poverty, and improve the livelihood in the basin. Such developments could result in basinwide cooperation or trigger conflicts among the riparian countries. A system dynamics model was developed for the entire Nile basin and integrated with the food and energy sectors in Egypt to investigate the future of the WFE nexus with and without the Grand Ethiopian Renaissance Dam (GERD) during filling and subsequent operation using basinwide stochastically generated flows. Different filling rates from 10% to 100% of the average monthly flow are considered during the filling process. Results suggest that the GERD filling and operation would affect the WFE nexus in Egypt, with the impact likely to be significant if the filling process occurred during a dry period. Food production from irrigated agriculture would be reduced by 9%–19% during filling and by about 4% during GERD operation compared with the case without it. The irrigation water supply and hydropower generation in Sudan will be reduced during the filling phase of the GERD, but this is expected to be improved during the dam operation phase as a result of the regulation afforded by the GERD. Ethiopian hydropower generation is expected to be boosted by the GERD during the filling and operation of the dam, adding an average of 15,000 GWh/year once GERD comes online. Lastly, the results reveal the urgency of cooperation and coordination among the riparian countries to minimize the regional risks and maximize the regional rewards associated with the GERD. [ABSTRACT FROM AUTHOR]

The current study represents the first molecular characterization of freshwater fish species in Egypt from two major fish resources; the River Nile and Lake Nasser. A total of 160 DNA barcodes using a 655-bp-long fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene were generated from 37 species belonging to 32 genera that represent 15 families from nine orders. The studied species were identified using different molecular-based identification approaches, in addition to the morphological identification, including neighbor-joining (NJ) trees, Barcode Index Number, and Automatic Barcode Gap Discovery (ABGD). The average genetic divergence based on the Kimura two-parameter model (K2P) within orders, families, genera, and species were 0.175, 0.067, 0.02, and 0.008, respectively. The minimum and maximum K2P distance-based genetic divergences were 0.0 and 0.154, respectively. Nucleotide diversity (π) varied among families and ranged between 0.0% for families Malapteruridae, Auchenoglanididae, Schilbeidae, Anguillidae, Centropomidae and Tetraodontidae and 17% for family Cyprinidae. The current study cautions against the lack of species coverage at public databases which limits the accurate identification of newly surveyed species and recommends that multiple methods are encouraged for accurate species identification. The findings of the current study also support that COI barcode enabled effective fish species identification in River Nile and Lake Nasser. Moreover, the results of the current study will establish a comprehensive DNA barcode library for freshwater fishes along the River Nile in Egypt. Egyptian freshwater fish DNA barcodes will contribute substantially to future efforts in monitoring, conservation, and management of fisheries in Egypt. [ABSTRACT FROM AUTHOR]

The Nile River stretches from south to north throughout the Nile River Basin (NRB) in Northeast Africa. Ethiopia, where the Blue Nile originates, has begun the construction of the Grand Ethiopian Renaissance Dam (GERD), which will be used to generate electricity. However, the impact of the GERD on land deformation caused by significant water relocation has not been rigorously considered in the scientific research. In this study, we develop a novel approach for predicting large-scale land deformation induced by the construction of the GERD reservoir. We also investigate the limitations of using the Gravity Recovery and Climate Experiment Follow On (GRACE-FO) mission to detect GERD-induced land deformation. We simulated three land deformation scenarios related to filling the expected reservoir volume, 70 km3, using 5-, 10-, and 15-year filling scenarios. The results indicated: (i) trends in downward vertical displacement estimated at −17.79 ± 0.02, −8.90 ± 0.09, and −5.94 ± 0.05 mm/year, for the 5-, 10-, and 15-year filling scenarios, respectively; (ii) the western (eastern) parts of the GERD reservoir are estimated to move toward the reservoir’s center by +0.98 ± 0.01 (−0.98 ± 0.01), +0.48 ± 0.00 (−0.48 ± 0.00), and +0.33 ± 0.00 (−0.33 ± 0.00) mm/year, under the 5-, 10- and 15-year filling strategies, respectively; (iii) the northern part of the GERD reservoir is moving southward by +1.28 ± 0.02, +0.64 ± 0.01, and +0.43 ± 0.00 mm/year, while the southern part is moving northward by −3.75 ± 0.04, −1.87 ± 0.02, and −1.25 ± 0.01 mm/year, during the three examined scenarios, respectively; and (iv) the GRACE-FO mission can only detect 15% of the large-scale land deformation produced by the GERD reservoir. Methods and results demonstrated in this study provide insights into possible impacts of reservoir impoundment on land surface deformation, which can be adopted into the GERD project or similar future dam construction plans.