Abstract:

Hydrochemical monitoring data of about 20 years and chemical analyses of groundwater samples collected in 2002 and 2003 in Beihai are analyzed and classified with methods of hydrochemical diagrams and Q-cluster analysis. The results show that groundwater in the northern part of the study area is mainly of Ca·Na-HCO₃ type and the hydrochemical characteristics of groundwater exhibit the effects of infiltration and dissolution of precipitation. Groundwater in the southern area is mainly of Na-Cl or Na·Ca-Cl type and the hydrochemical characteristics of groundwater follow a forward-hydrochemical evolution. Under natural conditions the ground-water in Beihai is characterized by low total dissolved solids(TDS)and low pH. The low TDS of groundwater is attributed to low TDS of rainwater, low contents of soluble salts in the aquifer media, quick water circulation and a long term of dissolution of the groundwater system.

Key words: groundwater, hydrochemistry, cluster analysis, coastal aquifer, Beihai