Water as key to the sustainable development goals of South Sudan – A water quality assessment of Eastern Equatoria State

Abstract

South Sudan, the world's newest nation is bestowed with huge fresh water resources. However, water resources management in South Sudan is lacking in water quality monitoring data and comprehensive plans of action for sustainable water resources development.Groundwater resources in particular have been exploited for domestic and irrigation use versus surface water. However, this groundwater withdrawal has not been monitored for its level and quality. To overcome this deficit, groundwater major ion chemistry in the South Sudan's Eastern Equatoria State was evaluated to determine its suitability for drinking, domestic, and irrigation purposes. A total of 176 groundwater samples were collected during wet (October 2014) and dry (April 2014) seasons. Sampling points were spread around the eight counties of Eastern Equatoria. Twenty two water samples were collected from each county. The samples were analysed for various physicochemical parameters including alkalinity, calcium hardness, conductivity, pH, salinity, TDS, total hardness, Na+, K+, Ca2+, Mg2+, Ba2+, CrT, Cd2+, Cu2+, FeT, Ni2+, Zn2+, Pb2+, NO3-, Cl-, F-, SO42-, PO43-, and SiO2. Groundwater irrigation quality indices including chlorinity index, Kelli Index, magnesium ratio, percentage of sodium must be replaced by sodium percentage (%Na), permeability index (PI), residual sodium carbonate (RSC), salinity index, sodicity index, and sodium absorption ratio (SAR), were calculated to determine the groundwater suitability for agricultural uses. The results were compared with South Sudan water quality guidelines (SSWQGs) and the WHO standards. Most of the water quality parameters met the WHO standards and SSWQGs prescribed for drinking and domestic purposes. The calculated irrigation water quality indices indicated the water suitability for irrigation.