Assessment of siltation and nutrient enrichment of Gilgel Gibe dam, Southwest Ethiopia

Devi, Rani; Tesfahune, Esubalew; Legesse, Worku; Deboch, Bishaw; Beyene, Abebe

doi:10.1016/j.biortech.2007.03.013

Cited by 75 publications

(59 citation statements)

References 2 publications

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“…Although the conservation measures might have reduced the discharge during the rain phase slightly, the amount of rainfall was clearly more important in determining the total amount of discharge (Table 3, Tables S1 and S2). Other studies have shown that upland conservation practices decreased direct runoff in Ethiopia [18,22,41] and elsewhere in the world [42,43]. The effect on discharge of the soil and conservation practices at the outlet in the Guale watershed was minimal, while in the Tikur-Wuha watershed, which could store the additional amount of infiltrated water, the direct runoff was decreased for comparable amounts of annual rainfall (Table 3, Tables S1 and S2).…”

Section: Overall Impact Of Soil and Water Conservation On Hydrologicamentioning

confidence: 86%

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Impact of Soil Depth and Topography on the Effectiveness of Conservation Practices on Discharge and Soil Loss in the Ethiopian Highlands

Akale

Dagnew

Belete

et al. 2017

Land

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Abstract:Restoration of degraded landscapes through the implementation of soil and water conservation practices is considered a viable option to increase agricultural production by enhancing ecosystems. However, in the humid Ethiopian highlands, little information is available on the impact of conservation practices despite wide scale implementation. The objective of this research was to document the effect of conservation practices on discharge and sediment concentration and load in watersheds that have different soil depths and topography. Precipitation, discharge, and sediment concentration were measured from 2010 to 2012 in two watersheds in close proximity and located in the Lake Tana basin, Ethiopia: Tikur-Wuha and Guale watersheds. The Tikur-Wuha watershed has deep soils and a gentle slope stream channel. The Guale watershed has shallow soils and a steep slope stream channel. In early 2011, the local community installed upland conservation measures consisting of stone and soil bunds, waterways, cutoff drains, infiltration furrows, gully rehabilitation, and enclosures. The results show that conservation practices marginally decreased direct runoff in both watersheds and increased base flow in the Tikur-Wuha watershed. Average sediment concentration decreased by 81% in Tikur-Wuha and 45% in Guale. The practices intended to increase infiltration were most effective in the Tikur-Wuha watershed because the deep soil could store the infiltrated water and release it over a longer period of time after the rainy season than the steeper Guale watershed with shallow soils.

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Section: Overall Impact Of Soil and Water Conservation On Hydrologicamentioning

confidence: 86%

“…Similarly, in the Koga watershed of the Lake Tana basin, 45% of the watershed is vulnerable to soil erosion [17]. Sheet erosion from the Gilgel Gibe catchment area, in southeastern Ethiopia, is estimated to be about 45 Tg y −1 [18].…”

Section: Introductionmentioning

confidence: 99%

Impact of Soil Depth and Topography on the Effectiveness of Conservation Practices on Discharge and Soil Loss in the Ethiopian Highlands

Akale

Dagnew

Belete

et al. 2017

Land

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“…It is therefore not unexpected that algal blooms occurred in the reservoir. Devi et al (2008) previously cautioned that the Gilgel Gibe I reservoir would become enriched with nutrients, which could induce eutrophication. In March 2008, measurements of chlorophyll a content ranged from 5 to 7 Kg/L, indicating a mesotrophic state (Duan et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Hydrological and anthropogenic influence in the Gilgel Gibe I reservoir (Ethiopia) on macroinvertebrate assemblages

Ambelu

Lock

Goethals

2013

Lake and Reservoir Management

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Ambelu A, Lock K, Goethals PLM. 2013. Hydrological and anthropogenic influence in the Gilgel Gibe I reservoir (Ethiopia) on macroinvertebrate assemblages. Lake Reserv Manage. 29:143-150.The Gilgel Gibe reservoir, which was built to fulfill the energy demand and the electricity export ambitions of Ethiopia, was characterized by low macroinvertebrate diversity mainly due to water level fluctuations, trampling of the littoral zone by cattle, nutrient input, and siltation from the catchment flow. The downstream river system was also affected by the dam due to a strongly decreased discharge as the water is diverted to Gilgel Gibe II hydropower plant through a 25 km underground tunnel. The study was based on seasonal macroinvertebrate sampling, water quality analyses, measurement of daily water level fluctuation, and recording of major anthropogenic activities. Hierarchical cluster analysis and canonical correspondence analysis were performed to determine relationships between the macroinvertebrate community composition and the environmental variables in the reservoir. The cluster analysis, Kruskal-Wallis ANOVA, and MANOVA permutation tests, revealed that differences in physicochemical water quality parameters and ecological quality metrics based on macroinvertebrates existed between the samples taken during periods with low, medium, and high water level seasons. Remedial actions could be important at basin and reservoir level to solve the identified problems and to improve the ecological water quality.

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“…Deforestation, overgrazing, and cultivation of slopes unsuitable for agriculture significantly enhance land degradation in Jimma [37]. Four catchments in Jimma with very high erosion susceptibility drain to the Gilgel Gibe hydropower dam, indicating the need for immediate actions to deal with erosion in order to protect the dam from siltation [38]. The construction of soil bunds and biological stabilization with, e.g., elephant grass or Sesbania sp, have proven to be efficient measures to reduce soil erosion in the Ethiopian highlands [37].…”

Section: Water Qualitymentioning

confidence: 99%

Water Quality Assessment of Streams and Wetlands in a Fast Growing East African City

Troyer

Mereta

Goethals

et al. 2016

Water

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Abstract:The combination of rapid urbanization, industrialization, population growth, and low environmental awareness poses a major threat to worldwide valuable freshwater resources, which provide important ecosystem services to humans. There is an urgent need to monitor and assess these resources, as this information is indispensable for sustainable decision-making and management. In this context, we analyzed the chemical and ecological water quality of the riverine environment of a fast growing city in Southwest Ethiopia for which we proposed possible remediation options that were evaluated with an empirical model. The chemical and ecological water quality was assessed at 53 sampling locations using the oxygen Prati index and the ETHbios, which is a biotic index based on macroinvertebrates. In addition, a microbiological analysis was performed to estimate the degree of fecal contamination. Finally, we analyzed the relationship between the oxygen content and the organic pollution to simulate the effect of organics removal from waste streams on the chemical water quality. Our results showed that the average values for dissolved oxygen (4.2 mg DO¨L´1) and nutrients (0.9 mg oPO 4 3´¨L´1 and 12.8 mg TAN¨L´1) exceeded international standards. Moreover, high turbidity levels revealed that land erosion is a severe problem in the region. Along the rivers, a significant increase in oxygen consumption and in nutrient concentrations was observed, indicating organic pollution originating from different diffuse and point sources of pollution. The lack of proper sanitation also led to exceedingly high abundances of fecal coliforms in the surface water (>320 MPN¨mL´1). However, fecal contamination was strongly reduced (>92%) after the polluted river water passed Boye wetland, indicating the purification potential of natural wetlands and the importance of conserving and protecting those ecosystems. The simulation results of the model showed that water quality could be substantially improved if municipal, industrial, and institutional wastewater was efficiently collected and transported to a treatment facility. Waste stabilization ponds and constructed wetlands are highly promising techniques, as they provide a cheap, effective, reliable, and sustainable way to purify wastewater. It is advised that the environmental awareness of the people via sensitization, education, and law enforcement is increased, as this is essential for sustainable development.

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Assessment of siltation and nutrient enrichment of Gilgel Gibe dam, Southwest Ethiopia

Cited by 75 publications

References 2 publications

Impact of Soil Depth and Topography on the Effectiveness of Conservation Practices on Discharge and Soil Loss in the Ethiopian Highlands

Impact of Soil Depth and Topography on the Effectiveness of Conservation Practices on Discharge and Soil Loss in the Ethiopian Highlands

Hydrological and anthropogenic influence in the Gilgel Gibe I reservoir (Ethiopia) on macroinvertebrate assemblages

Water Quality Assessment of Streams and Wetlands in a Fast Growing East African City

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