An assessment of water security and hydrology resources in the face of climate variability : the case study of Nkonkobe Local Municipality, Eastern Cape, South Africa

Abstract

South Africa is regarded as a semi-arid and water scarce country due to its low annual precipitation with a mean annual rainfall of 490mm. This study seeks to assess the effects of water security in the face of climate variability on hydrological resources in Nkonkobe Local Municipality, Eastern Cape, South Africa. The main objective of the research was to investigate climate variability parameters affecting water security in the Nkonkobe Local Municipality. The variability and trends in rainfall and temperature were analysed using descriptive statistics. Bivariate (Pearson) Correlation analysis was used to describe the effect of rainfall distribution and reservoir’s holding capacity. A vulnerability index model was applied to determine the water security status in the study area. The results showed that the inter-annual rainfall variability trends are not statistically significant at the 95% confidence level since the P = 0,197. This means that there is no relationship in the inter-annual rainfall variability trends. The regression model is represented by y = 3.0184x + 70.329 with R² = 0.0499 suggests that there is a weak linear relationship. The intra – annual rainfall variability over time is not statistically significant at the 95% confidence level means that there is no strong relationship in the intra – annual rainfall variability trends. From the linear regression the precipitation concentration index (PCI) decreased from 14.1 to 12.4 mm. The rainfall distribution and reservoir holding capacity of Binfield reservoir test of significance was positive (p value: 0.01) indicating that the two variables had a strong relationship and same is for Kat River reservoir which has a statistically significant linear relationship (p <.005).Temperature distribution and reservoir holding capacity of Kat River and Binfield reservoir have a statistically significant linear relationship (p < 0.01) and (p ‹ .005) respectively. The Binfield Reservoir has high resilience to climate variability, but the magnitude of impact could be managed as it falls under Type IV where there is Low Impact. Kat River and Binfield reservoirs faces great exposure or sensitivity, this is evidenced by the reservoir holding capacity that is in the Type I of the vulnerability index. The vulnerability index showed that the reservoirs water security is highly vulnerable. One of the key findings of this research was that vulnerabilities to form and function can be linked. For example, where reservoir level fluctuations change in response to the change in the climate variabilities, this affects the water security of the reservoirs. The findings illustrate the importance to enhance adaptation efforts both at the micro (Nkonkobe Local Municipality) and macro (national) levels, particularly for communities where the reservoirs are more vulnerable to climate variability.