Comparison of transfer function models for well-aquifer system response to atmospheric loading

摘要

The analysis of well water level response to periodic loadings is an effective way of studying the response of a well-aquifer system to crustal strains, and barometric response analysis of well water levels is one technique used for this. In this study, the transfer function of the water level to barometric pressure in 11 wells in Mainland China was analyzed, with response frequencies ranging from 0.1 cpd to dozens of cpd (for most wells > 40 cpd). Results showed that the barometric response of the water levels in eight wells coincide with the theoretical Gain-ω curve. Flow properties and hydraulic parameters of the corresponding eight well-systems were also analyzed. Results of three wells did not fit well with the theoretical Gain-ω curve, likely owing to the water level responses, which were affected by other factors besides barometric loading, leading to noise signals in the water level data. Although the model suitable for all aquifers is more general, more input parameters make it difficult to use for fitting. Since wells located in semi-confined aquifers are more common in the field, especially those used to identify strain/stress in shallow crustal, so simplified models for semi-confined aquifer are more suitable for most of these wells.