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Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershed—Ethiopia



Author(s)

Tamene Adugna Demissie1, Fokke Saathoff2, Yilma Seleshi3 and Alemayehu Gebissa2

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DOI:10.17265/1934-7359/2013.10.007

1. Department of Civil Engineering, Jimma Institute of Tehnology, Jimma University, Jimma 378, Ethiopia
2. Institute for Environmental Engineering, University of Rostock, Rostock 18051, Germany
3. Civil Engineering Department, Addis Ababa Institute of Technology, Addis Ababa University, Addis Ababa 150461, Ethiopia

Soil erosion/sedimentation is an immense problem threatening the live storage capacity of dam reservoirs in Ethiopia. This in turn reduces the power generation capacities of hydropower reservoirs. Therefore, studies which give insight into soil erosion/sedimentation mechanisms and mitigation methods is important. The high rate of soil erosion/sedimentation threats the lifespan of Gilgel Gibe-1 hydropower reservoir. The problem of sedimentation in Gilgel Gibe-1 will also affect Gilgel Gibe-2 which uses the water released from Gilgel Gibe-1. The sustainability of these hydropower plants needs catchment management practices that will reduce soil erosion. This paper presents the results of monthly and yearly sediment yield simulations experiments conducted for Gilgel Gibe-1 under different BMP (best management practice) scenarios. The scenarios applied in this paper are: (1) maintaining existing conditions; (2) introducing filter strips; (3) applying stone/soil bunds; (4) reforestation. The SWAT (soil and water assessment tool) was used to model soil erosion, identify soil erosion prone areas and assess the impact of BMPs on sediment reduction via simulations. The simulation results showed that applying filter strips, stone bunds and reforestation scenarios could reduce the current sediment yields at soil erosion prone areas and at the outlet of the catchment area which is the inlet to Gilgel Gibe-1 reservoir.

BMPs, SWAT, sedimentation.