Will Nzoia Basin in Kenya See Water Deficiency in Coming Decades as a Result of Climate Change

Abstract

This study investigates the potential change in the hydrologic cycle in Nzoia basin, one ofthe semi-arid basins of east Africa. An ensemble of 16 Global Climate Models data under different emissions scenarios are used in this study. The basin is expected to receive an increase in precipitation in all scenarios; from 5% to 15% by theend of this century compared to the base period 1990-1999. However, a 2 to 5ºC increase in temperature is expected to create an overall drier climate with reduced runoffs. The decadal averaged seasonal trends show that all major hydrological components except the runoff are expected to increase. An increase in temperature, together with more precipitation, could significantly increase actual evapotranspiration, ultimately may result a decrease in runoff by 14% and 18% in the 2020s and 2090s respectively compared to the base period. The elasticity analysis showed that the change in runoff is more sensitive to a change in temperature than precipitation for the 2060s and 2090s; and suggested that temperature will continue to be the dominating factor in future climate. In general, Nzoia will very likely experience a drier climate, further exacerbating the biomass production and food security.