Assessing The Impact Of Climate Change On Hydropower Generation In Kenya A Case Study Of Upper Tana River Basin

Abstract

Hydropower is currently Kenya’s second most dominant source of renewable electrical energy accounting for close to 49 per cent of power supply. The main source of hydropower in Kenya is the seven forks dams located in the Upper Tana river basin. Among the hydropower dams, Masinga Dam serves as a storage reservoir, controlling hydrology through a series of downstream hydroelectric reservoirs. The operation of Masinga dam is therefore crucial in meeting the power demands for the country, thus contributing significantly to the country’s economy. The main resource for hydropower generation is runoff which hugely depends on precipitation. Temperature and precipitation effects from global climate change could alter future hydrologic conditions in the upper Tana River basin and, as a result, hydropower generation. This research thesis is therefore a study that aims to assess the changes in hydropower generation in Kenya as a result of the changing climate, with a focus on the seven forks hydropower project. A simple approach assumes that hydropower systems will reduce generation if water supply reduces, and vice versa. The study uses a 30-year climate data to establish the precipitation trend and runoff variations of the study area. Based on the runoff changes, hydropower generation is estimated by relating the runoff changes to hydropower generation potential. The ArcSWAT model has been used for runoff analysis and simulation. ArcSWAT ArcGIS extension is a graphical user interface for the SWAT model developed to predict the impact of land management practices on water, sediment, and agricultural chemical yields in large, complex watersheds with varying soils, land use, and management conditions over long periods of time. The model is physically based and computationally efficient, uses readily available inputs and enables users to study long-term impacts. The results show that climate change is affecting the stream flow of the Upper Tana basin and hence leading to reduction in hydropower generation due to reduced or increased reservoir storage.