Hydraulic response of water level to seismic wave, earth tide and barometric pressure in deep well：A case study of the Fanxian well in Henan Province

The dynamic response of water level in a deep well to periodic loading provides natural experimental data for studying the response mechanism of deep well-aquifer system. Taking the Fanxian well in Henan Province, China, as an example, the hydraulic response characteristics of well water level induced by seismic wave, solid tide and barometric pressure was analyzed by using different hydraulic response models. The hydraulic parameters of the Fanxian well-aquifer were estimated based on the relevant hydraulic response models. The results show that in the process of high-frequency loading, the water flow in the well-aquifer system is mainly horizontal; while in the process of low-frequency loading, it is combined with horizontal and vertical water flow. The transmissivity estimated by the seismic response model with high frequency by period of 10—10² s is 7.20×10⁻³ m²/s, which is larger than the value 2.02×10⁻⁶ m²/s estimated using tidal response model with low frequency of period of 3.75×10⁴ s, and the estimation using barometric response model with the medium frequency of period of 10²—10⁴ s is between them, as 3.44×10⁻⁵ m²/s. Based on those results, we conclude that the pattern of water flow in the well-aquifer system is related to the frequency of periodic loading, and the scale effect exists while estimating the hydraulic parameters of the aquifer based on different hydraulic response models. The understanding obtained in this study can not only provide theoretical mechanism explanation for dynamic response of well water level, but also provide technical support for in-situ hydraulic parameters measurement in target aquifer.