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2007 Ground Water Summit |
Monday, April 30, 2007
4:30 p.m. - 7:30 p.m.
Tuesday, May 1, 2007
9:30 a.m. - 1:30 p.m.
Tuesday, May 1, 2007
4:30 p.m. - 7:30 p.m.
Hydrochemical Evolution of Ground Water in Shenzhen after Land Reclamation: Major Ion Chemistry of Coastal Ground Water
The need for more valuable land has encouraged reclamation in coastal areas of Shenzhen in the past decades. Land reclamation can alter the fresh-salt water relationships in coastal aquifers. The purpose of this study is therefore to identify the effect of land reclamation on groundwater chemistry especially the major ions in the groundwater bodies and examine the spatial and temporal variations of groundwater chemistry after land reclamation. Coastal land reclamation activities prolonged the groundwater flow path from land to sea and may hamper the connection of the coastal groundwater and the sea water. So in some extent land reclamation decrease the pressure of sea water intrusion. Inspection of major ionic composition of more than 200 groundwater samples in this study area indicated that three different water types located in different zones on the rout to the sea: Ca-HCO3 type groundwater; K+Na-Ca-HCO3-Cl type groundwater and Na-Cl saline groundwater. In particular, the Na-Cl type groundwater was close to the coastal line and the Ca-HCO3 type groundwater was about 2 kilometers away from the coastal line. Meanwhile the rMg/rCa and the (rMg+rCa)/rNa ratios strongly implicated that the Ca-HCO3 type groundwater gradually evolve to the K+Na-Ca-HCO3-Cl type groundwater after land reclamation. In a broad sense, the reactions responsible for the groundwater hydrochemical evolution in the study area were ion exchanges when the equilibrium of the coastal groundwater and seawater was disturbed by land reclamation. Temporal variations of (rMg+rCa)/rCl ratios also indicated that Ca-HCO3 type groundwater was changed for K+Na-Ca- HCO3-Cl type groundwater.