Spectral analysis of drought risk: A case of Bloemfontein, South Africa

Drought is defined as an insidious hydrometeorological hazards with a potential to negatively impacts on society, economy and environment. The current study aimed at analysing the drought potential risks in the study area for the protection of economy, environment and human lives. A 42-year long rainfall/precipitation data were collected from an online database. Dataset was subjected to quality check, where outliers were detected, removed and replaced by Expectation Maximum algorithm aided by SPSS. A non-parametric Mann Kendall’s test for trends was applied to detect monotonic trends present in the dataset. XLSTAT software was used in fitting annual data for a suitable probability distribution. The annual data fitted normal probability distribution with parameters, s=183.143, m=530.451 using Kolmogorov-Smirnov test criterion. The spectral analysis showed that the study area is expected to experience drought events every 2 years. The government and other relevant stakeholder authorities are therefore cautioned to put measures in place for the protection of property, environment and human lives and agricultural activities against adverse effects of droughts.