Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia)
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 mo...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-08-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/12/8/2237 |
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| author | Sofie Annys Tesfaalem Ghebreyohannes Jan Nyssen |
| author_facet | Sofie Annys Tesfaalem Ghebreyohannes Jan Nyssen |
| author_sort | Sofie Annys |
| collection | DOAJ |
| description | 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 (Q<sub>5</sub>) have declined (with factor 5), low flows (Q<sub>95</sub>) 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 <i>Tamarix nilotica</i> 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. |
| first_indexed | 2024-03-10T17:45:34Z |
| format | Article |
| id | doaj.art-0bc3a30a021f42bcb0271fe86a61b48b |
| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-10T17:45:34Z |
| publishDate | 2020-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Water |
| spelling | doaj.art-0bc3a30a021f42bcb0271fe86a61b48b2023-11-20T09:32:16ZengMDPI AGWater2073-44412020-08-01128223710.3390/w12082237Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia)Sofie Annys0Tesfaalem Ghebreyohannes1Jan Nyssen2Department of Geography, Ghent University, 9000 Gent, BelgiumDepartment of Geography and Environmental Studies, Mekelle University, Mek’ele 7000, EthiopiaDepartment of Geography, Ghent University, 9000 Gent, BelgiumDue 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 (Q<sub>5</sub>) have declined (with factor 5), low flows (Q<sub>95</sub>) 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 <i>Tamarix nilotica</i> 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.https://www.mdpi.com/2073-4441/12/8/2237river regulationhydropower generationdownstream hydrologydownstream river morphologyreservoir operation and management |
| spellingShingle | Sofie Annys Tesfaalem Ghebreyohannes Jan Nyssen Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia) Water river regulation hydropower generation downstream hydrology downstream river morphology reservoir operation and management |
| title | Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia) |
| title_full | Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia) |
| title_fullStr | Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia) |
| title_full_unstemmed | Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia) |
| title_short | Impact of Hydropower Dam Operation and Management on Downstream Hydrogeomorphology in Semi-Arid Environments (Tekeze, Northern Ethiopia) |
| title_sort | impact of hydropower dam operation and management on downstream hydrogeomorphology in semi arid environments tekeze northern ethiopia |
| topic | river regulation hydropower generation downstream hydrology downstream river morphology reservoir operation and management |
| url | https://www.mdpi.com/2073-4441/12/8/2237 |
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