The Role of Water Quality on the Water-Agriculture-Health Nexus: An Assessment of Surface Water in Vaalharts, South Africa

Abstract

This paper evaluated the quality and suitability of surface water in the Vaalharts area, South Africa, for human consumption, drinking, and irrigation purposes. Water quality constituents include water pH, EC, TDS, HCO3-, Cl-, SO4, Mg, Ca, k, Na, NO3, F, Fe, PO4, As, Al, Mn, Cr, Cu, Zn, B, Cd, Hg, Pb, N, Sb, Se, and the biological parameter included E. coli along surface waters as well as canals and dams. Sodium Adsorption Ratio, Sodium Percentage, Permeability Index, Residual Sodium Carbonate, Kelley’s Ratio, Magnesium Hazard, and Potential salinity irrigation water parameters indicated that the majority of the water samples are suitable for irrigation. The water quality index values showed that the majority of the samples are unsuitable for drinking but suitable for irrigation and industrial uses. E. coli in the surface water samples in the study area show unsafe water quality with high and very high risk for human health. Based on the classifying criterion of the Heavy Metal Pollution Index and Heavy Metal Evaluation Index, all the water samples are above the critical limit, therefore, unsuitable for human consumption. The carcinogenic risk (CR) concentrations of As, Cr and Cd were above the target risk.