[Hydrochemical Characteristic and Reasoning Analysis in Siyi Town, Langznong City].

The characteristics of main ions in Siyi Town, Langzhong City was influenced by geologicai conditions, topography and hydrological and meteorological conditions and other factors. Here we analyzed the groundwater ions characteristics which will play an important role in mastering the groundwater types, chemical origin and water quality in this area. The testing data of main ions in river water and groundwater in this area were analyzed with statistics, Piper diagram, Gibbs figure, and correlation analysis, proportional relationship of main ions and equilibrium analysis method analysis. The results showed that Ca2+ and Mg2+, and HCO3- dominant among cations and anions, respectively, and the hydrogeochemical types can be classified into HCO3-Ca type, HCO3 + SO4-Ca type and HCO3-Ca + Mg type. Main ions of all water are mainly affected by leaching effect in rock weathering process, which are dominantly dissolved from dolomite and calcite.