Given the scarcity of groundwater resources in the North China Plain (NCP) – a region important to both ecological integrity and socioeconomic development – understanding the spatiotemporal evolution and seasonal fluctuations of groundwater levels (GWLs) helps support effective groundwater management. This study integrates the Self-Organizing Map (SOM), an improved Innovative Trend Analysis (ITA), the Geographically Weighted Regression (GWR) model, and the Seasonal AutoRegressive Integrated Moving Average with eXogenous regressors (SARIMAX) model to analyze GWL variations in the NCP affected by meteorological and irrigation factors from 2018 to 2023. Winter wheat irrigation was estimated based on daily water stress factors, and spring irrigation demand across the region was effectively quantified. The results reveal significant spatial variability in GWLs, with levels generally higher in the northeast and lower in the southwest. The improved ITA method shows that the shallow GWLs rose by 26% and 39% in the low and high value parts and the deep GWLs rose by 11% and 20% in the low and high value parts, respectively. This indicates an overall upward trend in GWLs across the NCP. Shallow aquifers exhibit greater sensitivity to environmental changes and increasing spatial heterogeneity, while deep aquifers are relatively stable, with decreasing spatial variability. Quantitative analysis using the GWR model confirms that precipitation is the main source of groundwater recharge, while potential evaporation and irrigation are the main causes of discharge. Spring irrigation, in particular, exerts a strong influence on shallow aquifer GWLs. The SARIMAX model further demonstrates clear seasonal patterns in GWLs, highlighting the lagged effects of different influencing factors. Precipitation and irrigation are identified as the dominant drivers of seasonal groundwater fluctuations in the NCP. These findings provide useful insights for improving the prediction and adaptive management of groundwater resources in the region. • A comprehensive framework for refined characterization of groundwater level dynamics in the North China Plain. • Irrigation and precipitation affect seasonal fluctuations in groundwater levels. • An improved method of fine approximation of winter wheat irrigation is proposed. • The trends of the factors affecting shallow and deep water aquifer are different.
Gao et al. (Wed,) studied this question.