Quantitative analysis and discrimination of groundwater type in well-aquifer system

In this study, we quantitatively analyzed and determined groundwater types of well-aquifer system for the wells Banqiao, Dahuichang, Huanghua, Dadianzi, Fengzhen and Sanhaodi by using water level, barometric pressure and theoretical earth tide. Furthermore, combining with step response function of water level to barometric pressure in convolutional regression, barometric coefficient and tidal factor of M₂ wave are comparatively analyzed for each well in the studied period. The results show that: ① an obvious exponential relationship exists between lag time and step response function with “e” as the bottom, and the sign symbol of the coefficient before the base “e” could determine groundwater types of well-aquifer system; ② step response function is growing with lag time increase for artesian wells, and the larger the optimal step response function value is, the larger barometric coefficient and tidal factor of M₂ wave are, and the reverse is also true; ③ step response function decreases with latency increase for phreatic and half artesian wells, and because of hydraulic characteristics of aquifer, borehole structures and frequency of solid tidal waves, the relationship between the optimal step response function and barometric coefficient, tidal factor of M₂ wave is inconspicuous.