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Open AccessEditor’s ChoiceArticle

Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia)

1
Department of Geography, Ghent University, 9000 Gent, Belgium
2
Department of Geography and Environmental Studies, Mekelle University, Mek’ele 7000, Ethiopia
3
Department of Engineering Management, Antwerp University, 2000 Antwerpen, Belgium
*
Author to whom correspondence should be addressed.
Water 2020, 12(8), 2237; https://doi.org/10.3390/w12082237
Received: 30 June 2020 / Revised: 5 August 2020 / Accepted: 7 August 2020 / Published: 8 August 2020
(This article belongs to the Special Issue Fluvial Geomorphology and River Management)
Due to renewed interest in hydropower dams in the face of climate change, it is important to assess dam operations and management in combination with downstream impacts on rivers in (semi-)arid environments. In this study, the impacts of the Tekeze hydropower dam on downstream hydrology and river morphology were investigated, including impacts under normal and extreme reservoir operation conditions. Field observations, in-depth interviews, repeat terrestrial photographs, multi-year high-resolution satellite images, daily reservoir water levels and data on hourly to daily energy production were collected and studied. The results show that high flows (Q5) have declined (with factor 5), low flows (Q95) have increased (with factor 27), seasonal flow patterns have smoothened, river beds have incised (up to 4 m) and locally aggraded near tributary confluences. The active river bed has narrowed by 31%, which was accelerated by the gradual emergence of Tamarix nilotica and fruit plantations. A new post-dam equilibrium had been reached until it was disrupted by the 2018 emergency release, caused by reservoir management and above-normal reservoir inflow, and causing extensive erosion and agricultural losses downstream. Increased floodplain occupation for irrigated agriculture consequently provides an additional argument for reservoir operation optimization to avoid future risks for riparian communities. View Full-Text
Keywords: river regulation; hydropower generation; downstream hydrology; downstream river morphology; reservoir operation and management river regulation; hydropower generation; downstream hydrology; downstream river morphology; reservoir operation and management
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MDPI and ACS Style

Annys, S.; Ghebreyohannes, T.; Nyssen, J. Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia). Water 2020, 12, 2237. https://doi.org/10.3390/w12082237

AMA Style

Annys S, Ghebreyohannes T, Nyssen J. Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia). Water. 2020; 12(8):2237. https://doi.org/10.3390/w12082237

Chicago/Turabian Style

Annys, Sofie; Ghebreyohannes, Tesfaalem; Nyssen, Jan. 2020. "Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia)" Water 12, no. 8: 2237. https://doi.org/10.3390/w12082237

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