Hydrochemical Appraisal of Groundwater in Gash River Basin, Eastern Sudan

Abstract

The main goal of the present study is to evaluate the groundwater quality in Gash River Basin, Eastern Sudan. Groundwater is the main source in the area for all purposes: drinking, industrial as well as agricultural. Twenty-seven groundwater samples from agricultural farms in and around Kassala town were analyzed for their major ion concentrations. The TDS content of the collected samples ranged from 245.9 to 869.20 mg/l, whereas the EC values were below the maximum permissible limit of 1400 µS/cm prescribed by WHO for drinking water. The cation and anion concentrations were in the following order: Ca²⁺ > Na⁺ > Mg⁺² > K⁺ and ${{{\text{HCO}}_{3}}^{ - }} > {\text{Cl}}^{ - } > {{{\text{SO}}_{4}}^{2 - }} >{{{\text{NO}}_{3}}^{ - }}$. The main groundwater types identified are Ca–(Mg)–HCO₃ and Na–HCO₃ types. The samples fall in the water–rock interaction zone on the Gibb’s plot. Carbonates dissolution, silicates weathering and ion exchange are the major chemical processes controlling the groundwater chemistry in the study area. The groundwater in the area is suitable for irrigation in terms of sodium adsorption ratio SAR and residual sodium carbonate RSC, both of which are below the permissible limit, 10 and 1.25, respectively.