Climate change/variability implications on hydroelectricity generation in the Zambezi River Basin

Abstract

The study has analysed the effects of various factors on hydroelectric power generation potential to include climate change/variability, water demand, and installation of proposed hydroelectric power schemes in the Zambezi River Basin. An assessment of historical (1970–2000) power potential in relation to climate change/variability at existing hydro electric power schemes(Cahora Bassa, Kariba, Kafue Gorge and Itezhi-Tezhi) in the Zambezi River Basin was conducted. The correlation of hydroelectric power potential with climate change/variability aimed at observing the link and extent of influence of the latter on the former was investigated. In order to predict the future outlook of hydro electric power potential, General Circulation Models (GCM) were used to generate projected precipitation. The monthly simulated precipitation was extracted from the GCM for every sub basin and used to compute future precipitation. Further, future water demand in the sub basins of the Zambezi River Basin were estimated based on the respective population growth rate in each sub basin. Subsequently, water balance model, with projected precipitation and water demand input was used to determine projected run-offs of sub basins of the Zambezi River Basin. .Based on the projected run-offs of sub basins, reservoir storage capacities at existing hydro electric power schemes were estimated. The baseline assessment revealed a strong relationship between hydroelectric power potential and climate change/variability. The study also revealed that the main climate and other risks associated with current and future hydro electric power generation include projected dry years, floods and increasing water demand. The results indicate that the hydroelectric power potential has a tendency towards gradual reduction in its potential in all existing and proposed hydroelectric power schemes owing to climate change and increasing water demand.