The Hydrochemical Genesis Mechanism of Shallow Groundwater in the Kaifeng Section of the Lower Yellow River

ABSTRACT The lower Yellow River is a key watershed between the Haihe and Huaihe Rivers. The Kaifeng section, as a key river segment, holds significant geographical and ecological importance, and studying its shallow groundwater hydrochemistry is crucial for sustainable groundwater use. This study systematically analyzes the hydrochemical characteristics of shallow groundwater in the region using methods like Piper diagrams, Gibbs plots, ion ratios, and mathematical analysis to elucidate groundwater formation mechanisms, thereby filling a critical gap in systematic research on the influence of the Yellow River on adjacent groundwater systems. The findings show that shallow groundwater in the Kaifeng section is weakly alkaline, dominated by , Ca 2+ , Na + , and Mg 2+ , with HCO 3 ‐Ca (Mg, Na) type water accounting for 88.7%. The main hydrochemical mechanism is water‐rock interaction, with silicate and carbonate minerals as the primary sources. Moreover, groundwater composition is significantly influenced by lateral seepage from the Yellow River, especially on , Na + , and Ca 2+ concentrations. accounts for > 65.0% of anions, and Na + + Ca 2+ exceed 75.0% of cations. Groundwater recharge mainly comes from precipitation and river inflow. The ratios of , Na + , and Ca 2+ indicate that Yellow River seepage influence diminishes with distance, while rainfall impact increases.