Assessment Of Soil Erosion Potential And Its Impacts On Hydroelectricity Generation And Potable Water Treatment In Sebeya Catchment, Rwanda

Abstract

This study assessed the potential of erosion and its impact on Gihira Water Treatment Plant and Gisenyi Hydropower Plant in Sebeya catchment, Rwanda. The study determined the perception of the population on the existence of erosion, its impacts, major contributing factors, and organisations that contribute in its control in Sebeya catchment; it also characterized the catchment for risk of erosion potential, and determined the impact of erosion on Gihira WTP and Gisenyi HPP. Questionnaire was used in determining the perception of the population about erosion in the catchment. Digital Elevation Models (DEM), different digitized land uses, soil types, rainfall and available maps were used to characterize the catchment for erosion potential. Statistical tests were used to assess the differences in electricity generation between the raining seasons and dry seasons and how sediment transported in Sebeya River influences clean water production and the cost of its treatment. Water turbidity was used to characterize the variability of water quality. The results show that both local population and relevant administration perceive the existence of soil erosion in the catchment and considered deforestation, soil types, steep slopes, rainfall, farming methods, mining activities, and informal settlement as the major factors contributing to erosion in the catchment. The obtained maps during characterization indicate high potential for erosion especially because of poor agricultural practices, deforestation, soil types and steep slopes at upstream end of the catchment. The Gisenyi HPP was found to be more efficient in power generation during the dry season than in the raining season. The level of variability of turbidity was found to be statistically significant with the value of F greater than Fc. Production of potable water affairs to be high in some dry months than some months in the raining season and the cost of production of cubic meter of water is lower during the dry season than the raining season as expected. It was concluded that erosion is an issue in Sebeya catchment; it is leading to loss of soil fertility and agricultural lands and it is negatively impacting on hydropower generation and clean water production. The initiatives put in place to control erosion are producing results. It is recommended that more of these initiatives be put in place.