## 5 Conclusions  
1. Aiming at the limitations of current deformation monitoring means in the study area, the cooperative monitoring technology of SBAS-InSAR and GNSS was proposed. By employing SBAS-InSAR technology and high-resolution TerraSAR-X data, this study unveils the distribution and temporal sequence characteristics of deformations within the slope domain of the deep-dug expansive-soil channel section in the South-North Water-Diversion Middle-Route Project in China. The results exhibited two distinct deformation types: uplift and subsidence. Uplifted deformation was primarily concentrated downstream, while subsidence was predominantly observed in the middle and upstream regions of the section. The uplifted deformation areas surpassed the subsidence areas in both the extent and magnitude of occurrence, emphasizing their greater severity. Analysis of the temporal deformation characteristics at the measurement points within the deformation area revealed a cyclic pattern of \"uplift\(\rightarrow\)partial fallback\(\rightarrow\)uplift again\". Moreover, horizontal displacement demonstrated a continu \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Date**} & \multicolumn{3}{c}{**Level Measuring/mm**} & \multicolumn{3}{c}{**SBAS-InSAR/mm**} & \multicolumn{3}{c}{**Errors/mm**} \\  & **A1** & **A2** & **A3** & **A1** & **A2** & **A3** & **A1** & **A2** & **A3** \\ \hline
2 July 2020 & 3 & 4 & 4 & 4 & 5 & 5 & \(-1\) & \(-1\) & \(-1\) \\
24 July 2020 & 4 & 5 & 5 & 6 & 7 & 7 & \(-2\) & \(-2\) & \(-2\) \\
26 August 2020 & 12 & 13 & 13 & 14 & 15 & 15 & \(-2\) & \(-2\) & \(-2\) \\
9 October 2020 & 7 & 8 & 8 & 8 & 9 & 9 & \(-1\) & \(-1\) & \(-1\) \\
31 October 2020 & 4 & 5 & 5 & 5 & 6 & 6 & \(-1\) & \(-1\) & \(-1\) \\
3 December 2020 & 6 & 7 & 7 & 7 & 8 & 8 & \(-1\) & \(-1\) & \(-1\) \\
25 December 2020 & 5 & 6 & 7 & 6 & 8 & 8 & \(-1\) & \(-2\) & \(-1\) \\
5 January 2021 & 6 & 7 & 7 & 7 & 8 & 8 & \(-1\) & \(-1\) & \(-1\) \\
16 January 2021 & 10 & 11 & 11 & 11 & 12 & 12 & \(-1\) & \(-1\) & \(-1\) \\
7 February 2021 & 10 & 11 & 11 & 11 & 11 & 12 & \(-1\) & \(0\) & \(-1\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of level measuring vs. SBAS-InSAR. ous accumulation trend, with larger displacements occurring toward the inner part of the channel; (2) Combined with the geological engineering conditions of the study area, the deformation mechanism of the channel slope was elucidated. The study pointed out that the primary cause of the uplift deformation was the expansion of expansive soil upon contact with water. Conversely, the slight settlement was attributed to the combined effects of static loads from buildings, dynamic loads from large trucks, and the expansion of expansive soil in contact with water. Through the analysis of the soil moisture content and GNSS measurements, it was concluded that soil humidity exerted significant influence on vertical displacement at the surface. A lower soil moisture content corresponds to smaller vertical displacement, whereas higher soil moisture content results in larger vertical displacement. Moreover, there exists a strong positive correlation between surface vertical displacement and soil moisture; (3) Based on the study results and field research, it was observed that the surface of the channel slopes within the severely uplifted deformation area suffered varying degrees of damage, which was estimated to be further aggravated during the subsequent evolution of the soil in many dry-wet alternations. To comprehensively elucidate the deformation pattern and mechanism of the channel, we advocate for an extended duration of surface deformation monitoring in this area. This will facilitate a thorough understanding of the deformation process and enable appropriate repair measures to be recommended to ensure the safe operation of the channel.