Hydrochemical characteristics of groundwater and their controlling mechanisms in irrigation and non-irrigation areas - A comparative study in the Guanzhong Plain of China

Gaining insight into groundwater chemistry and its evolution in irrigation areas is essential for optimizing irrigation strategies. This study explores the origins and influencing variables of groundwater chemistry across both irrigated and non-irrigated areas of the Guanzhong Plain, China, aiming to elucidate how irrigation practices impact hydrochemical changes. Hydrochemical data, isotopic data, multivariate statistical techniques and hydrochemical methods were used in this study. The findings underscored that groundwater in the non-irrigation areas had low total dissolved solids (TDS), with 90% of the groundwater samples exhibiting the HCO₃–Ca·Mg type. In comparison, groundwater from the irrigation areas showed elevated TDS levels and diverse hydrochemical types, including HCO₃–Ca·Mg, HCO₃–Na, and SO₄·Cl–Ca·Mg types. These categories collectively represented 88% of the water samples from the irrigation areas. Isotopic and hydrochemical analyses revealed that groundwater in the irrigation areas experienced more intense evaporation and cation exchange. Furthermore, anthropogenic activities like sewage and manure had a more pronounced effect on groundwater chemistry in the irrigation areas. Groundwater suitability for irrigation deteriorated from the western irrigation area to the eastern irrigation area. This research offers a robust scientific foundation for the careful management and conservation of groundwater resources in the region.