Stable isotopes (δDVSMOW and δ18OVSMOW) and hydrochemical characteristics were analyzed to determine the groundwater and surface water characteristics of the Taizi River Basin in Northeast China. Total dissolved solids and major ion concentrations gradually increase along the Taizi River, and only parts of the middle and lower reaches were slightly reduced by replenishment from the Hun River and the tributaries of the eastern mountainous areas. The hydrochemical evolution of the surface water and groundwater may be due to a combination of mineral dissolution, mixing processes, cation exchange, and evaporation along the groundwater flow path. The geochemical and isotopic characteristics of the waters suggest that the surface water from the piedmont recharges the groundwater through faults and that precipitation near the mountain reservoirs contributes immensely to both water types. Lateral groundwater movement from the piedmont may be an effective source for replenishing river water in the middle and lower reaches. The geochemical and isotopic characteristics of the groundwater and surface water interaction in the Taizi River Basin contribute toward their comprehensive management.
Keywords: Geochemical evolution; Groundwater–surface water relationship; Hydrochemistry type; Northeast China; Stable isotope; Taizi River.