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Abstract:
The surface deformation monitoring of pumped storage power stations (PSPS) is essential for maintaining safety operation, since frequent and substantial variation of water level may increase the structure risk of PSPS. Due to the limitation of observations and the complicated effects caused by temperature, water level and structure performance, it is still a challenge to fully understand the long-term deformation mechanism of PSPS,. Take Xilongchi PSPS, the first high head PSPS in China, as an example, we collect 154 ascending Sentinel-1A images covering Xilongchi PSPS from March 2017 to October 2022, and more than 12 years’ GPS data of the five deformation monitoring stations on the upper reservoir. The deformation timeseries of the PSPS are then obtained by integrating GPS-InSAR techniques. Finally, the variational mode decomposition technique with strong anti-noise is utilized to extract the deformation characteristics. Our results show that the lower reservoir primarily exhibits sinking deformation, with a linear sinking rate of about 5.4 mm/y. The deformation decreases from the top to the bottom of the dam, which may be related to consolidation settlement. The surface of the upper reservoir is generally stable, with little apparent linear settlement deformation. However, its periodic deformation is evident and correlates with the changes of temperature and water level. Our work makes the first attempt to use long-term GPS and InSAR observations to monitor PSPS. The results demonstrate that GPS-InSAR integrated method would play an essential role in comprehending the deformation mechanism of PSPS around the globe.
