Impacts of climate change on water resources availability in Zambia: implications for irrigation development

The Zambian economy is predominantly based on exploitation of its natural resources. The water resources in particular are important for the socioeconomic development of the country. Managing water resources sustainably requires a good understanding of the current and future availability of these resources at local level: how much water is available, where is it available and when? This study assesses the spatial and temporal distribution of water resources and the impacts of projected climate change on water resource availability in Zambia. The study employs statistical downscaling of future climate scenarios and a water balance model in a hydrological modeling framework to assess the impacts of climate change on water availability. Unlike past studies done at national, regional or global levels, analysis in this study was done at the local river basin level. The main results indicate that temperature is projected to increase by 1.9 degrees C and 2.3 degrees C by 2050 and 2100, respectively, in Zambia. Rainfall is projected to decrease by about 3% by mid-century and only marginally by about 0.6% toward the end of the century across the country. These changes in rainfall and temperature will decrease water availability by 13% by the end of the century in 2100 at national level. At the river basin level, the northern basins are projected to stay the same or experience slight gains in water resources compared to those in the southern and western parts of Zambia where reductions up to 9% are projected. In particular, Zambezi, Kafue and Luangwa River basins are projected to have less water resources available due to reduced rainfall and higher temperatures. Two main implications for irrigation development follow in Zambia. More water-efficient irrigation technologies are needed and water resources will need to be better managed and regulated to cope with the projected water stresses due to climate change.