Study on the Evolution and Driving Factors of Shallow Groundwater Depth in Zhengzhou City

Abstract

Groundwater is one of the main water supplies for Zhengzhou City. Changes in groundwater depth negatively affect the water supply and geological stability of the city. Based on groundwater monitoring data from 1999 to 2024, this paper investigates the spatiotemporal changes in shallow groundwater depth in Zhengzhou and their driving factors. Trend analysis, ordinary Kriging interpolation, and Pearson correlation analysis were first employed to characterize the spatiotemporal evolution patterns of groundwater depth. A principal component regression (PCR) framework was then applied to reduce multicollinearity among hydro-climatic and water-use variables and to quantify their integrated relationships with groundwater depth at individual monitoring wells. The main findings are as follows: (1) Over the past 25 years, groundwater depth in Zhengzhou has gradually increased, with an average decline rate of 0.68 m per year. The most rapid increase occurred from 1999 to 2012. (2) Spatially, groundwater depth is greatest in the central urban area (average 35.2 m) and decreases with distance from the city center, forming a depression cone in the downtown area. (3) Anthropogenic factors dominate groundwater depth variation. Groundwater extraction shows a strong positive correlation with groundwater depth, and standardized regression coefficients indicate that domestic water consumption and groundwater supply are the key drivers of groundwater deepening and recovery, respectively. Rapid urbanization has led to water table decline, while changes in precipitation have had relatively minor effects. (4) Socioeconomic factors, such as expansion of construction land, population growth, and industrialization, have also contributed to the increase in groundwater depth by raising water demand and reducing infiltration recharge. The PCR-based analysis provides a parsimonious and spatially explicit basis for understanding groundwater-depth dynamics in a rapidly urbanizing plain city and offers practical guidance for targeted groundwater management, extraction control, and ecological water replenishment in Zhengzhou and similar regions.