Adaptation to the impacts of climate and demographic changes on water supply and demand in Nairobi, Kenya

Uncertainties, due to the impacts of climate change on water resources and demographic rise, pose challenges to the decision-making process in the management of water resources for urban cities thus, adequate planning ought to incorporate uncertainties. The study objective was to develop adaptation pathways using the Climate Risk Informed Decision Analysis (CRIDA) approach to enhance the water system performance. Using the hydrological model for the Thika-Chania Sub-catchment, the prediction of future water flows for 30 years period was done. A multivariate econometric approach was used to investigate the socio-economic factors on water use and forecasts on future water demand. The demand scenarios were based on different population growth patterns corresponding to the exponential growth and decreasing rate of increase growth, with per capita consumption scenarios of 85 and 170 lpd. The system performance was evaluated through stress testing to determine the behaviour under different scenarios. The results revealed an increasing supply–demand gap due to the impacts of climate and demographic changes. Adaptation strategies and their tipping points were established leading to the development of adaptation pathways. From the assessment of the flexible adaptation pathway, it was concluded that the non-revenue water strategy be considered as a priority project by the utility.