20. Hydrochemical Suitability of High Discharge Springs for Domestic and Irrigation Purposes in the Upper Blue Nile Basin, Ethiopia

This study shows the physio-chemical suitability of high discharge springs for domestic, livestock, and irrigation use in the Upper Blue Nile Basin, Ethiopia. Temperature, electrical conductivity (EC), total dissolved solids (TDS) and pH were measured during field investigation and in laboratory analysis. The results showed that the mean concentrations of cations (Na, Ca, K and Mg) were 14.66, 20.96, 5.32 and 12.35 mg/l, respectively, while those of anions (Cl, HCO₃, SO₄ and NO₃) were 5.08, 154.67, 1.84 and 12.17 mg/l, respectively. The mean concentrations of total hardness, alkalinity, TDS, EC and pH were 140.68 mg/l, 148.33 mg/l, 291.82 mg/l, 460.45 µ and 7.15, respectively. Based on the concentration of ions, CSPG1 and CSPG2 were found to be Ca²⁺ > Na⁺ > Mg²⁺ > K⁺. Birshelko, Tikurit, Lomi and AND3 springs have abundant cations Ca²⁺ > Mg²⁺ > Na⁺ > K⁺, while TSS1 springs have Mg²⁺ > Ca²⁺ > Na⁺ > K⁺, which are located in the Infranz and Andasa sub-basins. In the springs of TBL_SPG2, TBL_SPG3 and TBL_SPG4, which originate along the Birr sub-basin, the concentrations of cations were Na⁺ > Ca²⁺ > K⁺ > Mg²⁺, while the concentrations of anions from all springs were HCO₃ > NO₃ > Cl > SO₄. Three major water types were identified, which are Ca–Mg–HCO₃, Mg–Ca–HCO₃ and Na–Ca–HCO₃, which label springs as fresh (shallow) groundwater, transitional (mixed) groundwater and regional (alkaline) water type. The concentration of hardness except TBL_SPG4 (Geray) spring, the rest are moderately hard to hard water type which consume more soap and scaling the pipe of water supply source. Except for CSPG1, CSPG2 and Lomi spring, the concentration of K is unsuitable for domestic purposes and is above the permissible limits of the WHO and Ethiopian Standards. CSP1, CSPG2, ASPG1 and Lomi springs show high NO₃ concentrations that desire to be protected from uncontrolled sewerage systems and agricultural activity.