Search Results (28)

The construction of the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile has heightened transboundary water tensions in the Nile River Basin, particularly affecting downstream Sudan and Egypt. This study leverages African Earth Observation Data Cubes, specifically Digital Earth Africa’s Water Observations from Space (WOfS) platform, to quantify the hydrological impacts of GERD’s three filling phases (2019–2022) on Sudan’s Roseires Dam. Using Sentinel-2 satellite data processed through the Open Data Cube framework, we analyzed water extent changes from 2018 to 2023, capturing pre- and post-filling dynamics. Results show that GERD’s water spread area increased from 80 km² in 2019 to 528 km² in 2022, while Roseires Dam’s water extent decreased by 9 km² over the same period, with a notable 5 km² loss prior to GERD’s operation (2018–2019). These changes, validated against PERSIANN-CDR rainfall data, correlate with GERD’s filling operations, alongside climatic factors like evapotranspiration and reduced rainfall. The study highlights the potential of Earth Observation (EO) technologies to support transparent, data-driven transboundary water governance. Despite the Cooperative Framework Agreement (CFA) ratified by six upstream states in 2024, mistrust persists due to Egypt and Sudan’s non-ratification. We propose enhancing the Nile Basin Initiative’s Decision Support System with EO data and AI-driven models to optimize water allocation and foster cooperative filling strategies. Benefit-sharing mechanisms, such as energy trade from GERD, could mitigate downstream losses, aligning with the CFA’s equitable utilization principles and the UN Watercourses Convention. This research underscores the critical role of EO-driven frameworks in resolving Nile Basin conflicts and achieving Sustainable Development Goal 6 for sustainable water management. Full article

Transboundary water disputes arise as nations compete over shared water resources, exacerbated by climate change, socio-economic inequalities, and geopolitical tensions. These disputes, prominent in river basins like the Nile, Euphrates–Tigris, and Indus, threaten regional stability, water security, and ecological sustainability. This study investigates the drivers of such conflicts, evaluates the role of historical treaties, and examines the socio-economic and political dynamics, including hydro-hegemony and power imbalances, that influence governance. The research addresses the two following key questions: what factors drive transboundary water disputes, and what lessons from past conflicts and cooperation can guide future governance frameworks? Using a descriptive approach, the study critically analyses the literature and case studies to identify actionable insights. Specific objectives include analyzing drivers of conflict, assessing treaty efficacy, and deriving sustainable water-sharing strategies. Findings reveal that climate variability, population growth, and outdated agreements intensify challenges. In the Nile River Basin, Ethiopia’s Grand Ethiopian Renaissance Dam (GERD) strains relations, while in the Indus Basin, the outdated Indus Waters Treaty struggles to address modern demands. Similarly, unilateral actions in the Euphrates–Tigris River Basin (ETRB) exacerbate socio-political instability. The study underscores the importance of inclusive governance, equitable treaties, and integrated strategies, such as integrated water resources management and climate adaptation, to balance ecological, socio-economic, and geopolitical priorities. Linking these efforts to the Sustainable Development Goals highlights their potential to transform conflict into opportunities for regional stability and shared prosperity. Full article

Irrigation schemes represent the backbone of Sudan’s food security and economy. The Gezira, Rahad, and El-Gunied irrigation schemes depend mainly on the Blue Nile as their primary water source. However, the construction of the Grand Ethiopian Renaissance Dam (GERD) in the Blue Nile at the Sudan border has changed water flow regulations along the Blue Nile. Therefore, the Sudanese irrigation schemes that depend on the Blue Nile are affected by the operation and management of the GERD. This study used datasets derived from the Moderate Resolution Imaging Spectroradiometer (MODIS), specifically the enhanced vegetation index (EVI) and crop water use efficiency (CWUE), alongside climate time-series data obtained from the Climate Research Unit, to evaluate the performance of irrigation schemes in Sudan affected by climate variability and the construction and filling of the GERD. The analysis was carried out using R version 4.4.1 and spreadsheets. A dummy variable approach was employed to examine the effects of the GERD on the EVI, given the limited timeframe of the study, whilst Grey Relational Analysis was applied to investigate the influence of selected climate variables on the EVI. The results revealed that in the Gezira scheme, the impact of the GERD on the EVI was minimal, with rainfall and temperature identified as the predominant factors. In contrast, the construction of the GERD had significant negative repercussions on the EVI in the Rahad scheme, while it positively affected the El-Gunied scheme. The advantageous effects observed in the El-Gunied scheme were linked to the mitigation measures employed by the heightening of the Roseires Dam in Sudan since 2013. The Rahad and El-Gunied schemes exhibited heightened sensitivity to GERD-induced changes, primarily due to their reliance on irrigation water sourced from pumping stations dependent on Blue Nile water levels. Additionally, this study forecasts a decrease in cropping intensity attributed to the GERD, estimating reductions of 3.9% in Rahad, 1.5% in Gezira, and 0.8% in El-Gunied. Ultimately, this study highlights the detrimental impact of the GERD on Blue Nile water levels as a significant adverse factor associated with its construction and filling, which has led to a marked decline in CWUE across the irrigation schemes. The research underscores the intricate inter-relationship among environmental, political, institutional, and infrastructural elements that shapes irrigation efficiency and water management practices. This study concludes that enhancing irrigation efficiency and assessing the performance of irrigation schemes require significant consideration of institutional, economic, and political factors, especially in Sub-Saharan Africa. Full article

The Nile Basin has long been the subject of extensive research, reflecting its importance, which spans from its historical role in the development of ancient civilizations to its current significance in supporting rapidly changing socioeconomic conditions of the basin countries. This review synthesizes studies focusing on the past and future climate, hydrologic, and drought outlooks of the basin, and explores the roles played by large-scale atmospheric phenomena and water infrastructure on the basin’s climate and hydrology. Overall, the studies underscore the complexity of the Nile hydrological system and the necessity for improved modeling and data integration. This review serves as a guide to areas warranting further research by highlighting the uncertainties and inconsistencies among the different studies. It underscores the interconnectedness of climatic and hydrological processes in the basin and encourages the use of diverse data sources to address the data scarcity issue and ensemble models to reduce modeling uncertainty in future research. By summarizing the data and modeling resources employed in these studies, this review also provides a valuable resource for future modeling efforts to understand and explore of the basin’s complex climatic and hydrological dynamics. Full article

The Grand Ethiopian Renaissance Dam (GERD) on the Nile River has become a focal point in the fields of water diplomacy, economics, and environmental considerations in the Nile Basin. Announced during the Arab Spring in 2011, the GERD aims to address Ethiopia’s significant energy shortfall and foster regional economic growth by potentially doubling the country’s electricity output. However, this ambition has heightened tensions with downstream countries, especially Egypt and Sudan, which rely heavily on the Nile for their water needs. This paper examines the ongoing conflict surrounding the GERD, focusing on the deadlock situation despite considerable scholarly attention to its economic, political, and environmental dimensions. The analysis presented in this paper reveals the roots of contention by analyzing past treaties and the present negotiation status, illustrating the complex interplay between development goals, environmental sustainability, and regional water security. The paper advocates for a revised legal framework that moves beyond past agreements towards a more inclusive, cooperative management strategy for the Nile’s waters. It proposes the development of a new treaty between Egypt, Ethiopia, and Sudan, grounded in their 2015 Declaration of Principles agreement and inspired by successful international dispute resolutions. It also discusses the potential of neutral third-party interventions to facilitate unbiased negotiations grounded in the Graph Model for Conflict Resolution, emphasizing the importance of equitable and sustainable water governance. In essence, this research calls for a collaborative approach to resolve the GERD conflict, emphasizing the need for agreements that harmonize developmental ambitions with the water security of the Nile Basin nations. Full article

Some dams globally have negatively affected downstream structures. Constructing subsidiary weirs may solve this problem. This novel study focuses on investigating the parameters of seepage beneath the original structure and the proposed subsidiary weir. Conformal mapping and finite element methods are used for the analysis. The proposed subsidiary weir consists of a sloping central apron, flat aprons on both the downstream and upstream ends, and upstream and downstream sheet piles of varying depths. The existing structure also has sheet piles of different depths at its upstream and downstream ends, with an impervious layer situated at a specific depth below both the structures. The study derives equations for the simulation of the upwards pressure on both the structures, seepage rate, and exit gradient along the downstream bed and the filter at an intermediate location. Our own developed software for the analysis and a commercial software for numerical methods named Finite Element Heat Transfer (FEHT)-version-1are used to calculate these parameters. The accuracy of the analytical and numerical methods is verified by comparing the results with experimental data, which demonstrate a good level of agreement. This study also simulates the impacts of various factors, such as sheet pile configurations, the depth of the stratum beneath the structure, the ratio of effective heads, and the length of the intermediate filter. Full article

Dams are built for different purposes, but failure of a dam could result in extreme disasters such as floods. The Grand Ethiopian Renaissance Dam (GERD) was mainly built for power generation, but concerns about its safety, location and site conditions have led the downstream countries to investigate the GERD’s stability. This paper aims to investigate the impact of the failure of the dam on the downstream countries using the Hydrologic Engineering Center River Analysis System (HEC-RAS). Outflow hydrographs and flood inundation maps were provided through a hypothetical dam break scenario. An unsteady flow hydrodynamic routing with a 2D model was used to simulate the failure of the dam. A sensitivity analysis study of the output’s findings against breach parameters was also performed. The breach outflow discharge increases as the breach dimension increases. However, the peak discharge decreases with increasing breach formation time. Moreover, to prepare emergency action plans, it is important to predict the inundation depth, levels, arrival of flood waves, flood coverage area and water velocity. Furthermore, the results showed that Khartoum would turn into lakes within about 10 days and flood water depth would exceed 11 m at some locations in residential areas. Moreover, the flood waves overtopped the Roseires, Sennar and Merowe dams by 11, 7 and 20 m, respectively. In addition, the level of Lake Nasser would reach 188 m above sea level and the Aswan High Dam might be in great danger. Full article

An assessment of climate impacts in the hydrologic system of the Blue Nile basin is useful for enhancing water management planning and basin-wide policymaking. Climate change adaptation activities predominantly require an understanding of the range of impacts on the water resource. In this study, we assessed climate change impacts on the Blue Nile River using 30-year in situ climate data (1981–2010) and five bias-corrected General Circulation Models (GCMs) for future (2026–2045) climate projections of RCP8.5. Both historical and GCM precipitation projections show inter-annual and spatial variability, with the most significant increases in the rainy season and a significant decrease in the dry season. The results suggest the probability of an increase in total precipitation. The intensity and frequency of future extreme rainfall events will also increase. Moreover, the hydrological model simulation results show a likely increase in total river flow, peak discharges, flood inundation, and evapotranspiration that will lead to a higher risk of floods and droughts in the future. These results suggest that the operation of water storage systems (e.g., the Grand Ethiopian Renaissance Dam) should be optimized for Disaster Risk Reduction (DRR) and irrigation management in addition to their intended purposes in the Nile basin. Full article

Ethiopia began constructing the Grand Ethiopian Renaissance Dam (GERD) in 2011 on the Blue Nile near the borders of Sudan for electricity production. The dam was constructed as a roller-compacted concrete (RCC) gravity-type dam, comprising two power stations, three spillways, and the Saddle Dam. The main dam is expected to be 145 m high and 1780 m long. After filling of the dam, the estimated volume of Nile water to be bounded is about 74 billion m³. The first filling of the dam reservoir started in July 2020. It is crucial to monitor the newly impounded lake and its size for the water security balance for the Nile countries. We used remote sensing techniques and a geographic information system to analyze different satellite images, including multi-looking Sentinel-2, Landsat-9, and Sentinel-1 (SAR), to monitor the changes in the volume of water from 21 July 2020 to 28 August 2022. The volume of Nile water during and after the first, second, and third filling was estimated for the Grand Ethiopian Renaissance Dam (GERD) Reservoir Lake and compared for future hazards and environmental impacts. The proposed monitoring and early warning system of the Nile Basin lakes is essential to act as a confidence-building measure and provide an opportunity for cooperation between the Nile Basin countries. Full article

With the increasing number of reservoirs on the Nile River Basin, it has become important to understand the reservoir operations in the basin for coordinated water management among the various countries. With the lack of a proper framework for data sharing amongst the Nile basin countries, satellite remote sensing provides a simple transparent way to continuously monitor the changes taking place in reservoirs in all regions of the Nile River Basin. This paper presents a comparison between Sentinel-1- and Sentinel-2-derived reservoir water levels and the altimetry-based water level from G-REALM (Global Reservoirs and Lakes Monitor) for three major reservoirs downstream of the Millennium Reservoir impounded by the Grand Ethiopian Renaissance Dam (GERD) on the Nile River for the period of 2014–2021. Water surface extents were derived from Sentinel-1 using dynamic thresholds and from Sentinel-2 with the use of the NDWI (Normalized Difference Water Index). The water levels were estimated using a DEM-based contour matching technique. For Roseires Reservoir, the water levels from Sentinel agreed well with those from G-REALM (RMSE = 0.92 m; R² = 0.82). For Lake Nasser, the water levels also agreed well (RMSE = 0.72 m; R² = 0.85). For Lake Merowe, there was a significant mismatch in the derived water levels, mostly due to a lack of sufficient data from both sources. Overall, satellite imagery from Sentinel provides a very good alternative to altimetry-based water levels for the Nile River Basin. Full article

The construction of large-scale water reservoir facilities in transboundary river basins always arouses intense concern and controversy. The Grand Ethiopian Renaissance Dam (GERD) under construction in Ethiopia is perceived to affect water security in Egypt and Sudan. Therefore, this study investigated the water and sediment balance of the Blue Nile River (BNR) basin and identified the spatio-temporal variation in sediment and water yields along with the construction of GERD using Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) sediment and water yield models. The BNR basin experienced increasing water and sediment yields between 1992 and 2020 and has shown a growth trend since 2020. The lion’s share of water and sediment yields come from upstream of the GERD. Taken together, these results imply that the construction of the GERD will serve as a water storage and silt trap for Sudan and Egypt. Full article

This paper explores the possibility of achieving SDG 6.5 by 2030 in the Nile Basin by exploring the hydro-politics between the three main riparian states, Egypt, Ethiopia, and Sudan. Through a literature review of relevant sources, it is ascertained that, historically, Egypt has maintained a hegemonic control of the Nile through disputed treaties negotiated by Great Britain. However, the state-financed construction of the Grand Ethiopian Renaissance Dam (GERD) has the potential to shift this hegemonic control of the Nile Basin in favour of Ethiopia. While this construction may act as a source of political tension and low-scale conflict in the region, this paper critically examines how the implementation of a sustainable dam filling rate, Integrated Water Resource Management (IWRM), and the Nile Basin Initiative (NBI) can foster transboundary water cooperation between the three major players. In line with previous research, we argue that the GERD’s main effect is mostly positive, especially if the three main riparian states are actively cooperating and are considering advice from the scientific community. Full article

The impacts of climate change on the Nile River and Grand Ethiopian Renaissance Dam (GERD) along with the increased water demand downstream suggest an urgent need for more efficient management of the reservoir system that is well-informed by accurate modeling and optimization of the reservoir operation. This study provides an updated water balance model for Aswan High Dam Reservoir, which was validated using combined heterogeneous sources of information, including in situ gauge data, bias-corrected reanalyzed data, and remote sensing information. To investigate the future challenges, the spatial distribution of the annual/seasonal Aswan High Dam Reservoir surface air temperature trends over the period from 1979 to 2018 was studied. An increase of around 0.48 °C per decade in average annual temperature was detected, a trend that is expected to continue until 2100. Moreover, a set of machine learning models were developed and utilized to bias-correct the reanalyzed inflow and outflow data available for Aswan High Dam Reservoir. Finally, a policy tree optimization model was developed to inform the decision-making process and operation of the reservoir system. Results from the historical test simulations show that including reliable inflow data, accurate estimation of evaporation losses, and including new regulations and added projects, such as the Toshka Project, greatly affect the simulation results and guide managers through how the reservoir system should be operated in the future. Full article

Aswan High Dam Lake (AHDL) is one of the most relevant hot spots at both local and global levels after construction of the Grand Ethiopian Renaissance Dam (GERD) was announced. The management of AHDL is a vital task, which requires the input of reliable information such as the lake bathymetry, water level, and the water surface area. Traditional, bathymetric methods are still very expensive and difficult to operate. Nowadays, satellite data and remote sensing techniques are easily accessible. In particular, datasets produced by operational missions are freely and globally available, and may provide efficient and inexpensive solutions for the retrieval of quantitative parameters concerning strategic water bodies, such as AHDL. This work identifies the performance of Sentinel-3A optical imagery data in the visible and NIR bands from the two optical instruments SLSTR and OLCI, and proposes the integration with Sentinel-3A radar altimetry from SRAL instrument applied to AHDL. This preliminary and first study investigated the relationship between the reflectance data and in situ data for water depth after a bathymetric campaign in the deep-water region using statistical regression models. These statistical models showed promising results in terms of correlation value (R² > 0.8) and normalized root mean square errors (NRMSE < 0.4). Also, Heron’s formula was applied to combine optical imagery and Sentinel-3 altimetry water level datasets to estimate water storage variations in AHDL. In addition, equations governing the relationship between water level, water surface area, and water volume were analyzed. The work is very useful for all authorities and stakeholders dealing with large water bodies. Full article

The destruction of cultural heritage caused by dams represents a major issue especially in an age of climate change and narrowly focused development policies. To counteract this phenomenon, archaeologists and cultural heritage experts have relied upon rescue archaeology practices generally limited to fieldwork methodologies, while remote sensing of satellite imagery remains under-considered. To bridge this gap, we build on a multidisciplinary collaboration exploring the potential of Synthetic Aperture Radar (SAR) and open access multispectral satellite imagery, for quantifying the archaeological evidence located within a prospective reservoir area before dam construction. Based on previous research by Marchetti (2020) claiming the necessity for ad hoc protocols to document and monitor the impact of dams on cultural heritage, we selected two complementary situations: the planned dam of Halabiyeh in Syria and the under construction Grand Ethiopian Renaissance Dam (GERD) in Ethiopia. These case studies were analyzed with state-of-the-art methodologies to develop a feasible workflow that may contribute to fostering the use of satellite imagery in operational contexts such as those represented by these particular cases, and be replicated by archaeologists in other areas. The workflow is designed to be integrated to ground-truthing methodologies into two dedicated protocols named Pre-Construction Archaeological Risk Assessment (PCARA) and Pre-Flooding Rescue Archaeological Program (PFRAP) which could eventually become a standard procedure for rescue archaeology in dams areas. Full article