The Yellow River has played an indispensable role in supporting Chinese civilization because it provides water resources and rich soil for agriculture. This study analyzes the major ions and the isotopic ratios of the hydrogen (δD), oxygen (δ¹⁸O), and carbon (¹⁴C) of groundwater samples to identify the sources of recharge and the impact of the Yellow River on the Changqing-Xiaolipu karst aquifer. The major ion/Cl⁻ ratios generally follow the mixing line between the Yellow River and the karst groundwater recharge in the southern mountain areas, indicating the importance of mixing under natural influences in the Yellow River Basin. The dominant hydrochemical type of karst groundwater is Ca·Mg-HCO₃·SO₄, whereas that of Yellow River water is Ca·Na·Mg-SO₄·Cl. Most karst groundwater consists of 10–30% Yellow River water, indicating that the water resources of the Yellow River Basin are generally supplemented by the Yellow River. Therefore, the Yellow River must be considered during the characterization of the chemistry and budget of water resources in the Yellow River Basin.

Groundwater represents a critical resource for sustaining the livelihoods of both urban and rural populations, facilitating economic and social development, and preserving ecological equilibrium. This study leverages groundwater quality monitoring data from the northern Baiquan spring basin (NBSB) to elucidate groundwater hydrochemical characteristics and decipher the temporal variability in water quality. Findings suggest that groundwater within the NBSB is predominantly weakly alkaline and characterized as hard-fresh, with HCO₃⁻ and Ca²⁺ as the predominant ions, which collectively demarcate the hydrochemical type as predominantly HCO₃-Ca. The principal constituents of NBSB groundwater are influenced predominantly by the weathering of carbonates and silicates alongside the dissolution of gypsum and halite. Moreover, agricultural operations and similar human activities have exerted an impact on the hydrochemical attributes of NBSB’s groundwater. Generally, fluctuations in groundwater anion concentrations over time are more pronounced than those of cations, exemplified by a significant upward trend in the major ion concentrations at the BQ03 monitoring site in the later stages. While the general groundwater quality within the NBSB is deemed satisfactory, most monitoring sites have experienced an escalation in water quality indices over time, notably at BQ03, which warrants serious attention. The findings of this research contribute to the efficient management and sustainable utilization of groundwater resources in the NBSB.