Abstract
Climate variability poses a pressing shift to the hydrological cycle and diminishing water resources availability. This shift is a prevalent challenge for day-to-day activities in the Olifants River, South Africa. This study assessed rainfall, minimum and maximum temperature variability, trend analysis, and change point detection in the Olifants River using numerous statistical analysis methods, such as coefficient of variation, Kurtosis, skewness, Pettitt, Buishand, von Neumann, Standard normal homogeneity test (SNHT), Mann-Kendall, and Sen's slope tests for the period from 1988 to 2014. The results showed that annual rainfall in most stations had moderate variation, while limited stations were negatively skewed and not normally distributed. Most of the stations, such as X1E003, B5E004, and B1E003, showed less variability (CV < 20), while the rest of the stations showed moderate variation ranges (20 < CV < 30) for rainfall datasets. The results of kurtosis and skewness ranged from -0.41 to 1.10 and -0.12 to 0.46 for rainfall; -0.03 to 0.92 and -0.61 to -0.17 for maximum temperature; and 0.24 to 1.61 and -0.18 to 0.14 for minimum temperature, respectively. Furthermore, the majority of stations were negatively skewed for annual maximum and minimum temperatures. Unexpectedly, the homogeneity tests for annual rainfall and maximum temperature depicted favorable results, while a few stations were found to be non-homogeneous for minimum temperature. Specifically, the trend analysis indicators such as Kendall's tau, S, p-value and Sen’s slope showed ranges from -0.03 to 0.15, -11 to 53, 0.28 to 1.0, and -1.95 to 4.98 for rainfall; 0.08 to 0.15, 29 to 51, 0.30 to 0.56, and 0.009 to 0.025 for maximum temperature; and 0.13 to 0.24, 45 to 85, 0.08 to 0.36, 0.01 to 0.014 for minimum temperature, respectively. The trend analysis results revealed that the highest percentage of stations were showing an increasing trend, while the magnitude varied slightly for annual rainfall, maximum, and minimum temperatures. Sustainable and innovative climate variability mitigation measures must be initiated to reduce the effects of variability in agricultural productivity and environmental changes. Future researchers can investigate the effects of natural and anthropogenic activities on water resources and their implications for water availability.