Abstract
Groundwater hydrochemical evolution has influences on the rational use and conservation of water resources. This paper which
takes MapGIS as the platform is aimed at demonstrating the evolution of shallow groundwater hydrochemistry in Guanzhong
basin (China) by adopting mathematical statistics, ratios of ion pair equivalents, geochemical simulation. The direction of
evolution is dependent on the geological, geomorphological, and hydrogeological conditions of the study area. The spatial
distribution of hydro-chemical types, mineralization, hardness and ion content are horizontally zoned. In the areas both south and
north of the Wei River and west of the Jing River, the shallow groundwater hydrochemical evolution is constrained by water -
rock interactions. While in the north of the Wei River and east of the Jing River, the shallow groundwater hydrochemical
evolution is relatively complex because of the evaporation-concentration process, mixed dilution and water-rock interactions.
The causes of differences in water-rock interactions are mainly related to the relative dissolution/precipitation of calcite,
dolomite, gypsum，fluorite and halite, the dissolution/escape of CO2 and the positive ion exchange of Ca2+-Na+.