Chemical Characteristics of Phreatic Water in Yinchuan Plain and Their Control Factors

Based on the geology and hydrogeology, the chemical characteristics of phreatic water in Yinchuan plain are analyzed according to the analysis results of 272 water samples collected in 2003. The factors controlling the composition of phreatic water are investigated. Results show the TDS, concentrations of Na⁺, Cl^- of phreatic water generally increase along the direction from SW to NE, the chemical types changes in the sequences of HCO₃ ^-rarrHCO₃ ^-+SO₄ ^2-rarrSO₄ ^2-rarrHCO₃ ^-rarrSO₄ ^2-+Cl^-rarrCl^-+SO₄ ^2-. The factors controlling and affecting the chemical composition of phreatic water in Yinchuan plain are mainly geological and hydrogeological conditions, the composition of recharge water, the soluble salt content of soils, water-rock interaction, and concentration by evaporation. To improve the quality of phreatic water in Yinchuan Plain, the development intensity of shallow groundwater should be increased, so as to lower the level of groundwater further and quicken its circulation.