Analysis of the abnormal variation of water level at Yingxiu well, Sichuan Province

From 2021 to 2022, the water level in the Yingxiu well showed a large anomalous annual decline. In this study, we analyzed the correlation between rainfall and the water level and conducted a quantitative exclusion analysis of the impact of rainfall on the water level. The environment surrounding the observation site were also investigated, geochemical tests were conducted on water samples, and stress changes in the wellbore aquifer system were analyzed to determine the abnormal cause of this annual change. The results showed that the annual change in the water level in Yingxiu well dropped significantly in 2022, and this was controlled by both rainfall factors and other factors. At the beginning of 2022, the parameters of the aquifer in the observation period fluctuated significantly, indicating that the annual water level gradient was related to the tectonic static stress of the aquifer that may be related to changes or adjustments in the regional tectonic stresses before and after a series of earthquakes with a magnitude 6 occurring from June to September 2022.