CR 76:59-72 (2018)  -  DOI: https://doi.org/10.3354/cr01528

ABSTRACT: Extreme precipitation exerts damaging impacts on both society and ecosystems. Understanding projections of extreme precipitation is part of a resilient response to its impacts. To avoid the generalities inherent in regional projections, projections focussing on an individual country are necessary. However, studies focusing on Zambia are still limited and, future climate variability is poorly understood. Here, the frequency and intensity of extreme precipitation over Zambia are analysed for the period 2021-2100 using an ensemble of 5 CMIP5 models from those recommended by the Intergovernmental Panel on Climate Change (IPCC). Our analyses demonstrate that there will be an increase in precipitation intensity and a decrease in frequency over Zambia from the middle of the 21st century. Notably, there is a significant increase in the maximum number of consecutive dry days and significant decreases in the number of days with at least 1 and 10 mm of precipitation. Annual total precipitation significantly reduces while the frequency of exceedance of the 95th and 99th percentile thresholds increases significantly. The annual maxima of 1 d and consecutive 5 d precipitation are also projected to increase. Results from the spatial analysis show that the greatest increase in the number of consecutive dry days is around Siavonga, Kasama and Isoka, up to the border of Zambia and Tanzania. The reduction in precipitation is projected to be steepest over Northwestern Province and lessens southwards. The steepness of these trends generally falls between -0.22 and 0.47 on Sen’s slope estimator at a significance level of 5%. In nearly all cases the risk of rejecting the null hypothesis H₀ when it is true is lower than 1%. Our study provides a novel overview of expected climate trends in Zambia, which can act as guidelines for strategic planning of flood and drought prevention.

KEY WORDS: Precipitation · Intensity · Frequency · Projections · CMIP5 · Zambia