Abstract: The hydrochemical characteristics and water quality status of karst confined water in Dawu water source of Shandong Province were investigated using mathematical statistics, correlation analysis, Piper's plot, Gibbs model and ion ratio method by analyzing 57 groundwater samples taken in 2017. The major ion characteristics and causes were examined, and the water quality was assessed by comprehensive evaluation method. Results reveal that Ca²⁺ and Na⁺ are the major cations of groundwater, accounting for 82.8% of the total cations; HCO₃^-, SO₄^2-, and Cl^- are the main anions, accounting for 91.9% of the total anions. HCO₃·SO₄-Ca· Mg(Ca), HCO₃·SO₄·Cl-Ca·Mg(Ca), and HCO₃·Cl-Ca·Mg(Ca) are dominant hydrochemical patterns. The hydrochemical components are mainly controlled by weathering and dissolution of carbonate rock. The groundwater quality is above class Ⅲ, which accounts for 47.4% of the total water samples, while Ⅳ and Ⅴ classes occupy 52.6% of the total water samples.

Key words: groundwater, hydrochemical characteristics, water quality evaluation, Dawu water source, correlation analysis