Hydrochemical characteristics of groundwater in the Heihe River Basin

In arid environments, groundwater may represent the most important resource for most uses. The chemical evolution of the groundwater provides insight in the interaction of water with the environment and contributes to better resource management. In August 2008, a total of 39 groundwaters were collected, and major chemical ions were measured in order to reveal the hydrochemical component and geochemical processes and groundwater movement in the Heihe River Basin, northwest China. The results show that dominated by Na+, Ca2+, SO42-, HCO3- and Cl-. Most of the shallow groundwater is typically characterized by Na-Mg-SO4- Cl type and Na-Mg-SO4- HCO3 type in deep groundwater. Dissolution of gypsiferous rocks and/ or anhydrite -bearing rocks are important processes for chemical compositions of water in the study area, and produce water with increased Na+, Ca2+, SO42- concentrations, and also increased total dissolved solids in groundwater. Mineral dissolution/ weathering of evaporates dominates the major element hydrochemistry in the study area. There is no good hydrological connection to a greater extent for groundwater in the middle and lower reaches.