Quantitative evaluation of the influence of rainfall changes and groundwater exploitation on the groundwater level: a case study of the northern Huangqihai Basin, China

Based on the hydrogeological perspective, the variation in the groundwater level (W) was selected as the analysis factor, and the rainfall changes and groundwater exploitation (Q(GE)) were considered to be the influencing factors. The influence of the two factors on W in the northern Huangqihai Basin was analyzed qualitatively and quantitatively. Results showed that both rainfall and Q(GE) showed increasing trends from 1996 to 2020 based on the M-K trend test, while the W values decreased. The correlation between Q(GE) and W was weaker in wet years than in normal years but was the highest in dry years. The mutation time was determined to be 2004. Based on the slope-changing ratio of the cumulative quantity method and the elastic coefficient method, it was determined that the contribution of rainfall changes to W was 22.08% and that of Q(GE) was 77.92%. This study highlights the effectiveness of the integration of qualitative analyses and quantitative evaluation for identifying the influence of external factors on groundwater and well documents that the elastic coefficient method can be used in this field. More attention should be focused on the scientific management of Q(GE) to minimize its negative influence on the sustainable development of groundwater.