Abstract:

In the Taiyuan basin, the statistical methods and geochemical model have been systematically used to study the hydrochemical types of groundwaters, spatial distribution of geochemistry, and evolutional mechanism. The results show that the shallow groundwater of the basin can be divided into the fresh groundwater in the border of the basin, the salt groundwater in the center of the basin, the high mineralization degree sulphate groundwater. The third type of the shallow groundwater has been recharged by the bedrock fissure groundwater rich in SO₄^2-in the border of the basin. The moderate deep groundwaters of the basin have been divided into the moderate deep groundwater in the border of the basin, the moderate deep groundwater in the center of the basin, and the moderate deep mixed groundwater. There are two kinds of hydrochemical mechanisms of the groundwater evolution:the first is that the groundwater is recharged by the high mineralization sulphate karst groundwater; the second is that the increase of TDS of groundwater is attributed to the evaporation during the evolution process. From the border to the center in the Taiyuan basin, the moderate deep groundwater obviously show the hydrochemical distributional regularities,and there are two high value areas in the center of the Taiyuan basin. The hydrochemical types of the groundwater are successively Ca·MgHCO₃→Na·CaHCO₃·SO₄→Na·MgHCO₃·Cl→NaHCO_3。

Key words: Taiyuan basin, groundwater, hydrogeochemistry characteristic, evolutional mechanism