Evolution characteristics and genesis of shallow groundwater in Lücheng area of Danyang City

Based on the field investigation and sampling analysis, the hydrochemical characteristics, types and genesis of shallow groundwater in Lücheng area of Danyang City were analyzed by using the methods of statistics, Piper trigram, Gibbs model and correlation analysis.The results show that the pH value of shallow groundwater in this area has little change, belonging to neutral and slightly alkaline water. Ca²⁺ and Na⁺ were dominant in cations, while HCO₃^- was the absolute dominant in anion.The main hydrochemical types are HCO₃-Ca, HCO₃-Ca·Na, HCO₃·SO4-Ca·Na, HCO₃·Cl-Ca·Na and HCO₃-Ca·Na·Mg. In recent years, TDS of shallow groundwater shows a decreasing trend, indicating a certain degree of desalination phenomenon. It is found that the comprehensive effects of Quaternary sedimentary environment, rock weathering, hydrogeological conditions and human economic activities are the main reasons leading to the evolution characteristics and differences of shallow groundwater in this area.