JWARP  Vol.7 No.16 , November 2015
Performance Evaluation of Sediment Basins: Case Study of Keya Hydropower Plant in Rwanda
Abstract: Keya Hydropower Plant (HPP) is a run-off-river plant which can be an effective green solution contributing to the current energy demand in Rwanda but a huge amount of sediment contained in water of Sebeya River on which this plant is built results in loss of the plant capacity. The aim of this study was to conduct the performance evaluation of Keya HPP sediment basin located in Rubavu district, western province of Rwanda. Specifically, laboratory tests of sediment, efficiency of the basin, assessment of sedimentation problems on HPP operations, proposition of technical options for increasing the removal efficiency of sediment basin and other options for reducing sediment at the source of generation were performed using different methods including interviews and questioning Keya hydropower technicians, field sediment sampling followed by hydrometer and Particle Size Distribution (PSD) analysis. Analysis was made in University of Rwanda (UR) Soil Mechanics laboratory. MICROSOFT EXCEL and Graphisoft Archicad 18 softwares with Massachusetts Institute of Technology (MIT) soil classification were used as data analysis tools. Results showed that the overall efficiency removal of the diversion headwork was 85%. However, after comparing sediment concentration at the inlet and outlet of the sediment basin, it was found that the basin removed only 22% of sediment from diverted water toward the turbine. This means that 78% of sediment escapes the basin to cause erosion on the turbine components resulting in reduction of the plant capacity from 2.2 MW to 900 KW. To ensure sustainable solution to sediment issues in Keya HPP, an upstream sediment trap reservoir is proposed. It is recommended also that Rwanda Energy Group (REG) should work together with Rwanda Natural Resource Authority (RNRA) at national level to ensure sustainable development of erosion control in the Sebeya catchment area.
Cite this paper: Munyaneza, O. , Majoro, F. , Mutake, S. and Hagenimana, E. (2015) Performance Evaluation of Sediment Basins: Case Study of Keya Hydropower Plant in Rwanda. Journal of Water Resource and Protection, 7, 1387-1398. doi: 10.4236/jwarp.2015.716112.

[1]   Lysne, D., Glover, B., Stole, H. and Tesaker, E. (2003) Sediment Transport and Sediment Handling. Hydraulic Design. Norwegian University of Sciences and Technology, Noruega-Trondneim.

[2]   Thapa, B. and Dahlhaug, O.G. (2003) Sand Erosion in Hydraulic Turbines and Wear Rate. International Conference on Hydropower, Hydro Africa-2003, ICG, Arusha, 17-19 November 2003.

[3]   Envirotech (2014) Environmental Audit for hydropower Plants Lot 3, Kigali. Energy, Water and Sanitation (EWSA).

[4]   Masters, G.M. (2004) Renewable and Efficient Electric Power Systems. Wiley Interscience.

[5]   Ardüser, C. and Karcheter, L. (2009) Civil Works for Micro Hydro Power Units. (C. S. Prof. Dr.-Ing.Peter Gonsowski, Ed.) School of Architecture, Civil Engineering and Geomatics, University of Applied Science, Ladhak.

[6]   OSSBERGER (2012) OSSBERGER Cross Flow Turbine.

[7]   Morris, G. and Fan, J. (1989) Reservoir Sedimentation Handbook. McGraw-Hill Publishing Company, New York.

[8]   Teffera, A. and Leikun, M. (1999) Soil Mechanics. Addis Ababa University, Addis Ababa.

[9]   Rwanda Natural Resources Authority (RNRA) (2014) Technical Study of Designing a Retention Pond for Controlling Flood at Sebeya River. Kigali, Republic of Rwanda.

[10]   Neopane, H.P. (2010) Sediment Erosion in Hydro Turbine. Norwegian University of Science and Technology (NTNU), Trondheim.

[11]   Batuca, D.G. (2000) Silting and Desilting of Reservoirs.

[12]   Pandey, V. (2011) Research Report on Feasibility Study of Micro Hyrdopower in Nepal. Nepal Engineering College, Bhaktapur.

[13]   MINAGRI (2011) Dam and Irrigation Sites, Final Design of 4 Sites for Land. Report Submitted to Ministry of Agriculture and Animal Resources (MINAGRI). G. Karavokyris & Partners Consulting Engineers S.A. and P. Antonaropoulos & Associates S.A.