## 3 Methods and Materials Processing
### Materials Processing  
In this study, Sentinel-1A/B single look complex (SLC) SAR images were processed using the standard SBAS-InSAR processing flow in SARscape software (version number of 5.6) to obtain the average deformation rate and temporal deformation sequence results of the study area. Subsequently, a deformation thematic map of the study area was produced and analyzed using ArcGIS software (version number of 10.8). This comprised the following steps:  
* Preprocessing of SAR image data. To begin, we obtain SAR images and DEM that cover the study area, and we crop them based on the research scope to shorten the processing time. In addition, the satellite orbit information needs to be corrected using the POD data, and external DEM is used for registration to improve accuracy. Before this step, the DEM in the geographic coordinate system needs to be transformed into the DEM in the SAR image projection coordinate system;  
* Generation of the connection diagram. Baseline estimation is conducted on the pre-processed SAR image data, followed by the establishment of temporal baseline connection maps using appropriate temporal baseline thresholds. For this study, the spatial baseline threshold is set at 5% of the critical baseline, and the temporal baseline threshold is set at 60 days, resulting in the generation of 419 interferometric image pairs;  
* Interference processing. Interference processing of SAR image data to obtain multiple interferograms. In this study, a multi-look ratio of 4:1 was set for the range and azimuth directions to suppress speckle noise in the communication, and the Goldstein method was employed for residual phase filtering of the interferogram. A coherence threshold of 0.2 was set, and the Minimum Cost Flow (MCF) method was used for phase unwrapping. The obtained differential interferograms and unwrapped phase maps were visually interpreted, and 202 pairs with unsatisfactory interferometric and unwrapping effects were eliminated. Finally, the spatio-temporal baseline connection map is presented in Figure 4;* Refinement and reflattening. Orbit refinement and phase shift calculation are performed using cubic polynomials based on the selected ground control points (GCPs) to eliminate possible slope phases and correct for satellite orbits and phase shifts;
* Deformation inversion estimation. The first inversion is conducted to estimate the deformation rate and residual topography, and the corresponding wavelet decomposition level is set to remove the residual topography as needed. Subsequently, the second inversion is performed, with high-pass filtering in the time domain and low-pass filtering in the spatial domain, to eliminate the influence of atmospheric phase. Finally, the time series deformation results are obtained;
* Geocoding. The deformation results in the SAR coordinate system are converted to the geographic coordinate system of the reference DEM, and then the Arcgis software is used to create thematic maps, such as annual average surface deformation rate and cumulative deformation maps, for the subsequent related analysis. The time series used for wavelet analysis requires equally spaced temporal sampling. Despite the fixed 12-day revisit period of the Sentinel-1A/B satellite, some images may be missing or excluded from the SBAS-InSAR processing stream, resulting in a nonhomogeneous temporal distribution of the LOS deformation time series. Therefore, we used linear interpolation to fill in missing deformation data. It should be noted that linear interpolation does not introduce false periodicity, as its linear features only produce a constant or DC component in the frequency domain [47]. The rainfall and water level data collected in this study were sampled daily. To maintain the same sampling interval as in the InSAR time series, we downsampled the rainfall and water level data.