Interactions between surface water and groundwater in selected tributaries of the Wei River (China) revealed by hydrochemistry and stable isotopes

Fast population growth and rapid economic and societal development drive the massive extraction of groundwater, increasing complications for the relationship between surface water and groundwater. To study the surface water and groundwater interactions in the north and south tributaries of the Wei River (Xin and Jing Rivers), China, 17 surface water samples and 30 groundwater samples were collected and analyzed. Hydrochemistry and stable isotopes were used to study the surface water and groundwater interactions in the two rivers. The results showed that the main hydrochemical type of both surface water and groundwater in the Xin River watershed was HCO3-Ca•Mg, while that of the Jing River water was SO4•Cl-Na, and groundwater was of HCO3-Na type. The hydraulic connectivity between the surface water and groundwater of the two rivers was generally weak. The contributions of surface water, precipitation and lateral groundwater flow to groundwater in the Xin River were 48%, 34% and 18%, respectively, whereas in Jing River they were 27%, 51% and 22%. The river in the south of the Wei River has greater hydraulic connectivity than the river in the north. The results provide scientific basis for the integrated management of surface water and groundwater in the areas.