Comparative Study of Methods for Evaluating Shallow Groundwater in Plain Areas

【Objective】 Predicting change in groundwater table in response to natural and anthropogenic influence is a prerequisite in groundwater resource management. This paper compares several methods commonly used in studying groundwater dynamics based on the shallow groundwater exploration in plain areas in central China. 【Method】 The study was based on shallow groundwater resources in Puyang City in Henan province. We analyzed the groundwater dynamics in the region using three methods: water balance method, dewatering-volume method, and time series method. 【Result】 The time series method is applicable only to areas where groundwater development and utilization do not show considerable change with time. In contrast, the water balance method and dewatering volume method are more mechanistic, providing more accurate results as they consider potential changes in groundwater usage and management. As the dewatering volume method divides the studied region into subunits based on administrative regions rather than hydrogeological conditions, it could lead to significant differences when compared to measurements from monitoring boreholes. The water balance method considers factors such as current groundwater development, hydrogeological conditions and groundwater management measures, and it is hence more accurate for analyzing groundwater dynamics. 【Conclusion】 Results calculated by the improved groundwater balance method proposed in this paper are consistent with ground-truth data. It is more reliable for evaluating the response of shallow groundwater table to change in management and usages in plain areas.