Hydrogeological and hydrogeochemical studies for salt water intrusion on the south coast of Laizhou Bay, China

Sea water intrusion has occurred on the east and southeast coasts of Laizho u Bay, China, since the 1970s (Wu et al, 1993). In 1981, on the adjacent so uth coast, the intrusion of salt water originating from brine was observed. In this area, the salt water intrusion was caused by the excessive pumping of fresh water in aquifers, Moreover, the simultaneous pumping of fresh wa ter and salt water/brine formed a complicated ground water flow field. The data obtained from observation webs were used to analyze the origin of the salt water and brine, and the genesis of the bicarbonate/sodium water zone. All data suggest that the brine originated from ancient sea water, and tha t the bicarbonate/sodium water was formed by cation exchange, The variation s of chemical compositions along representative flowpaths and the relations hips between such variations and salt water intrusion were also discussed.