Optimal Operation of Hydropower Reservoirs under Climate Change: The Case of Tekeze Reservoir, Eastern Nile

Abera, Fikru F.; Asfaw, Dereje H.; Engida, Agizew Nigussie; Melesse, Assefa M.

doi:10.3390/w10030273

Cited by 38 publications

(30 citation statements)

References 57 publications

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“…They used a combination of different regional climate model, and they showed potential increase in precipitation that my lead to an increase in energy production. Abera et al [60] in the same basin found also a similar pattern in precipitation and temperature increase, with consequent increase of discharge. They find a potential increase of the water volume stored in the reservoir, leading to an increase in production, similarly to what we found here for the GERD reservoir.…”

Section: Limitations and Outlookssupporting

confidence: 55%

Impact of Prospective Climate Change Scenarios upon Hydropower Potential of Ethiopia in GERD and GIBE Dams

Bombelli

Tomiet

Bianchi

et al. 2021

Water

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Ethiopia is growing fast, and the country has a dire need of energy. To avoid environmental damages, however, Ethiopia is looking for green energy polices, including hydropower exploitation, with large water availability (i.e., the Blue Nile, the greatest tributary of Nile river). Besides other dams on the Omo river, the GIBE family, Ethiopia is now building the largest hydropower plant of Africa, the GERD (Grand Ethiopian Renaissance Dam), on the Blue Nile river, leading to tensions between Ethiopia, and Egypt, due to potentially conflictive water management. In addition, present and prospective climate change may affect reservoirs’ operation, and this thereby is relevant for downstream water users, population, and environment. Here, we evaluated water management for the GERD, and GIBE III dams, under present, and future hydrological conditions until 2100. We used two models, namely, Poli-Hydro and Poli-Power, to describe (i) hydrological budget, and flow routing and (ii) optimal/maximum hydropower production from the two dams, under unconstrained (i.e., no release downstream besides MIF) and constrained (i.e., with fair release downstream) simulation. We then used climate change scenarios from the reports CMIP5/6 of the Intergovernmental Panel on Climate Change (IPCC) until 2100, to assess future hydropower production. Our results demonstrate that the filling phase of the GERD, particularly critical, have optimal filling time of 5 years or so. Stream flows at GERD could be greater than the present ones (control run CR) at half century (2050–2059), but there could be large decrease at the end of century (2090–2099). Energy production at half century may increase, and then decrease until the end of century. In GIBE III discharges would increase both at half century, and at the end of century, and so would energy production. Constrained, and unconstrained simulation provide in practice similar results, suggesting potential for shared water management in both plants.

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Section: Limitations and Outlookssupporting

confidence: 55%

Impact of Prospective Climate Change Scenarios upon Hydropower Potential of Ethiopia in GERD and GIBE Dams

Bombelli

Tomiet

Bianchi

et al. 2021

Water

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“…According to , the suspended sediment response to climate change generally followed the patterns of simulated changes in streamflow. Climate change can also affect future reservoir planning and management [18]. The volume variability of lake is more responsive to extreme climate events than to other anthropogenic factors [7].…”

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confidence: 99%

The Effect of Climate Change on Loss of Lake Volume: Case of Sedimentation in Central Rift Valley Basin, Ethiopia

et al. 2018

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Evaluating the impact of climate change on sediment yield has become one of the major topics in climate research. The purpose of this study was to investigate sediment yield contribution to lake volume change under changing climatic conditions in the Central Rift Valley Basin. The ensemble mean of five regional climate models (RCMs) in the coordinated regional climate downscaling experiment (CORDEX)-Africa was considered for the purpose of this study. The climate variables (precipitation, minimum and maximum temperatures) in RCMs were bias corrected against observed data using linear scaling (LS), power transformation (PT), variance of scaling (VS), and quantile mapping (QM). Two emission scenarios, the Representative Concentration Pathways, RCP4.5 and RCP8.5, were considered for the future scenario period . Better results were obtained when the ensemble values of the bias correction methods were used. Hence, the projected values of climate variables after bias correction were used in the Soil and Water Assessment Tool (SWAT) hydrological model to estimate the sediment yield contribution to lake volume change due to climate change. The results show that the average projected precipitation will decrease by 7.97% and 2.55% under RCP4.5 and RCP8.5, respectively. On average, the maximum temperature will increase by 1.73 • C and 2.36 • C under RCP4.5 and RCP8.5, respectively, while the minimum temperature will increase by 2.16 • C and 3.07 • C under RCP4.5 and RCP8.5, respectively. The average annual sediment yield contributions to Lake Ziway were 431.05 ton/km 2 and 322.82 ton/km 2 for the Meki and Ketar rivers, respectively, in the historical period . The study also reveals that the annual sediment yield that was estimated for the Meki River was 323 ton/km 2 and 382 ton/km 2 under RCP4.5 and under RCP8.5, respectively. The sediment estimations for the Ketar River were 157 ton/km 2 and 211 ton/km 2 under RCP4.5 under RCP8.5, respectively. This will decrease the rate of volume change in Lake Ziway by 38% under RCP4.5 and by 23% under RCP8.5. The results show that the life expectancy of the lake is likely to increase under climate change scenarios. This will help water resources managers make informed decisions regarding the planning, management, and mitigation of the river basins.Hydrology 2018, 5, 67 2 of 18 reservoirs, ponds, and rivers. The sedimentation of the water bodies reduces their capacity and the useful lifespan of the reservoir. Sediment yield can be described as the amount of sediment that would enter into a reservoir located at the outlet of the basin [1]. It is the net result of soil erosion and processes of sediment accumulation, so it depends on variables that control water and sediment discharge to reservoirs [2]. Sediment yield is influenced by many factors, which include topography, soil, climate, land use, and drainage characteristics [3][4][5][6]. The problem of sedimentation is aggravated by human activities and climate change. A study conducted by Belete [7] on Lake Hawasa showed that sediment...

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“…Abera, Asfaw, Engida, and Melesse () studied optimal operation (using HEC‐ResPRM model) under climate change for the Tekeze (hydropower) reservoir on the Eastern Nile (294,040 km 2 in Ethiopia and Sudan, see also Kim & Kaluarachchi, ). Outputs of the Downscaling Experiment over African domain (CORDEX‐Africa) under RCP4.5 and RCP8.5 resulted into an increase of power storage potential up to +25% and +30% under RCP4.5 and RCP8.5 until 2100, in response to an increase of monthly inflows except in May to June.…”

Section: Discussionmentioning

confidence: 99%

Operation of two major reservoirs of Iran under IPCC scenarios during the XXI century

Akbari‐Alashti

Soncini

Dinpashoh

et al. 2018

Hydrological Processes

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We assess the effects of prospective climate change until 2100 on water management of two major reservoirs of Iran, namely, Dez (3.34 × 109 m3) and Alavian (6 × 107 m3). We tune the Poly‐Hydro model suited for simulation of hydrological cycle in high altitude snow‐fed catchments. We assess optimal operation rules (ORs) for the reservoirs using three algorithms under dynamic and static operation and linear and non‐linear decision rules during control run (1990–2010 for Dez and 2000–2010 for Alavian). We use projected climate scenarios (plus statistical downscaling) from three general circulation models, EC‐Earth, CCSM4, and ECHAM6, and three emission scenarios, or representative concentration pathways (RCPs), RCP2.6, RCP4.5, and RCP8.5, for a grand total of nine scenarios, to mimic evolution of the hydrological cycle under future climate until 2100. We subsequently test the ORs under the future hydrological scenarios (at half century and end of century) and the need for reoptimization. Poly‐Hydro model when benchmarked against historical data well mimics the hydrological budget of both catchments, including the main processes of evapotranspiration and streamflows. Teaching–learning‐based optimization delivers the best performance in both reservoirs according to objective scores and is used for future operation. Our projections in Dez catchment depict decreased precipitation along the XXI century, with −1% on average (of the nine scenarios) at half century and −6% at the end of century, with changes in streamflows on average −7% yearly and −13% yearly, respectively. In Alavian, precipitation would decrease by −10% on average at half century and −13% at the end of century, with streamflows −14% yearly and −18% yearly, respectively. Under the projected future hydrology, reservoirs' operation would provide lower performance (i.e., larger lack of water) than now, especially for Alavian dam. Our results provide evidence of potentially decreasing water availability and less effective water management in water stressed areas like Northern Iran here during this century.

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Optimal Operation of Hydropower Reservoirs under Climate Change: The Case of Tekeze Reservoir, Eastern Nile

Cited by 38 publications

References 57 publications

Impact of Prospective Climate Change Scenarios upon Hydropower Potential of Ethiopia in GERD and GIBE Dams

Impact of Prospective Climate Change Scenarios upon Hydropower Potential of Ethiopia in GERD and GIBE Dams

The Effect of Climate Change on Loss of Lake Volume: Case of Sedimentation in Central Rift Valley Basin, Ethiopia

Operation of two major reservoirs of Iran under IPCC scenarios during the XXI century

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