Water-food-energy nexus for transboundary cooperation in Eastern Africa

Establishing cooperation in transboundary rivers is challenging especially with the weak or non-existent river basin institutions. A nexus-based approach is developed to explore cooperation opportunities in transboundary river basins while considering system operation and coordination under uncertain hydrologic river regimes. The proposed approach is applied to the Nile river basin with a special focus on the Grand Ethiopian Renaissance Dam (GERD), assuming two possible governance positions: with or without cooperation. A cooperation mechanism is developed to allocate additional releases from the GERD when necessary, while a unilateral position assumes that the GERD is operated to maximize hydropower generation regardless of downstream users' needs. The GERD operation modes were analysed considering operation of downstream reservoirs and varying demands in Egypt. Results show that average basin-wide hydropower generation is likely to increase by about 547 GWh/year (1%) if cooperation is adopted when compared to the unilateral position. In Sudan, hydropower generation and water supply are expected to enhance in the unilateral position and would improve further with cooperation. Furthermore, elevated low flows by the GERD are likely to improve the WFE nexus outcomes in Egypt under full cooperation governance scenario with a small reduction in GERD hydropower generation (2,000 GWh/year (19%)).

Mosul Dam, NW Iraq: Is a Safe Dam??

Mosul Dam is located in the northwestern part of Iraq impounding the Tigris River; about 60 km north of Mosul city. This project is multipurpose project; to provide water for irrigation, flood control and hydropower generation. The dam is 113 m high and 3650 m long including the spillway. The dam is earth fill type with a mud core. The dam was designed to impound 11.11 km3 because it is based and underlain by gypsum beds alternated with limestone and marl. Therefore, it is planned to use continuous grouting to fill the karst caverns. The used quantity exceeded 95000 tons of solid grouting materials since 1986 up to 2014. After all, is the dam safe? The details are given in the current article.

Analyzing the Applicability of Random Forest-Based Models for the Forecast of Run-of-River Hydropower Generation

Analyzing the impact of climate variables into the operational planning processes is essential for the robust implementation of a sustainable power system. This paper deals with the modeling of the run-of-river hydropower production based on climate variables on the European scale. A better understanding of future run-of-river generation patterns has important implications for power systems with increasing shares of solar and wind power. Run-of-river plants are less intermittent than solar or wind but also less dispatchable than dams with storage capacity. However, translating time series of climate data (precipitation and air temperature) into time series of run-of-river-based hydropower generation is not an easy task as it is necessary to capture the complex relationship between the availability of water and the generation of electricity. This task is also more complex when performed for a large interconnected area. In this work, a model is built for several European countries by using machine learning techniques. In particular, we compare the accuracy of models based on the Random Forest algorithm and show that a more accurate model is obtained when a finer spatial resolution of climate data is introduced. We then discuss the practical applicability of a machine learning model for the medium term forecasts and show that some very context specific but influential events are hard to capture.

Deriving reservoir operating rules considering ecological demands of multiple stations

Reservoirs play important roles in hydropower generation, flood control, water supply, and navigation. However, the regulation of reservoirs is challenged due to their adverse influences on river ecosystems. This study uses ecoflow as an ecological indicator for reservoir operation to indicate the extent of natural flow alteration. Three reservoir optimization models are established to derive ecological operating rule curves. Model 1 only considers the maximization of average annual hydropower generation and the assurance rate of hydropower generation. Model 2 incorporates ecological objectives and constraints. Model 3 not only considers the hydropower objectives but also simulates the runoff and calculates the ecological indicator values of multiple downstream stations. The three models are optimized by a simulation-optimization framework. The reservoir ecological operating rule curves are derived for the case study of China's Three Gorges Reservoir. The results represent feasible schemes for reservoir operation by considering both hydropower and ecological demands. The average annual power generation and assurance rate of a preferred optimized scheme for Model 3 are increased by 1.06% and 2.50%, respectively. Furthermore, ecological benefits of the three hydrologic stations are also improved. In summary, the ecological indicator ecoflow and optimization models could be helpful for reservoir ecological operations.

Simulation Of the Conical Gravitational Water Vortex Turbine (GWVT) Design in Producing Optimum Force for Energy Production

Sustainable electricity power supply is crucial especially for less populated rural area. Micro hydropower generation in rural area is important in providing electricity especially in off-grid electricity area. This study aims to predict and harness power from micro hydropower generation through conical gravitational water vortex turbine (GWVT) via SOLIDWORKS flow simulation. Conical GWVT under study was designed as fully enclosed system with conical turbine basin. Two different turbine orientations were simulated i.e., vertical and horizontal at different blade angle designs i.e., 25°, 45°, 75°, 90°, and 120° and with different number of blades i.e., 8, 12, and 18 while forces were harnessed at tangential (z-axis) direction. The simulation results showed that it was possible to run and produce force from conical GWVT design in a fully enclosed system. It was found that vertical turbine orientation produced a slightly higher force than horizontally orientated turbine, using 12 runner blades at 90° angles where the distributed forces were 15.31N and 14.12N respectively, at tangential (z-axis) direction. The results are useful to predict turbine’s torque for small capacity micro hydropower electricity generation prior to actual conical GWVT set up, in rural area, to minimise cost implication and construction issues.