## 1 Introduction  
In China, The Middle Route of the South-North Water Diversion Project, which is the \"lifeline\" for water supply to Beijing, Tianjin, Hebei, and Henan, has been operating uninterruptedly and overloaded for more than seven years. Since its official opening on 12 December 2014, supplying more than 50 billion cubic meters of water to the north and directly benefited 140 million people which is the source of water for 70-80% of Beijing and 100% of Tianjin. It has not only relieved the water shortage in large and medium-sized cities along the route but also greatly improved the ecology of rivers along the route. It created opportunities and space for economic restructuring and industrial transformation. It is of great significance for safety monitoring [1; 2; 3]. However, the country's heavy weapons are \"overdue\" and \"over the standard service\", so the risk of failure cannot be fully controlled and security monitoring is significant. At present, the safety monitoring of the South-North Water Diversion Project is mainly based on precision leveling measurement, GNSS (Global Navigation Satellite System) measurement and sensors installed inside the project. These methods have low spatial sampling density and can only obtain local point settlement. It is difficult to grasp the information of deformation at non-measurement points and the continuous deformation trend of the dam as a whole [4; 5; 6]. At the same time, the cost of human and material resources is high. The first two methods require the measurement personnel to enter the deformation area, which increases the danger; the latter method's sensors are difficult to maintain and will gradually lose sensitivity and even efficacy with the operation of the dam. There is an urgent need for a new method to measure the deformation of dams and surrounding landscapes in a large area at a low cost. InSAR (Interferometric Synthetic Aperture Radar) technology with all-day, all-weather, strong penetration, and surface domain deformation monitoring capability provides a new idea for wide-scale, high-precision safety monitoring of the South-North Water Diversion Project [7; 8; 9; 10; 11; 12]. The PS-InSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) technique proposed by [PERSON] et al. [13] can obtain millimeter-level deformation monitoring accuracy. The InSAR technique has been promoted in algorithm research [14; 15; 16; 17; 18; 19; 20; 21], surface subsidence [22; 23; 24], disaster warning [25; 26; 27; 28], permafrost deformation [29; 30; 31], and other fields have made significant breakthroughs. In recent years, InSAR technology has also been widely used in water conservancy project safety monitoring. [PERSON] et al. [32] first conducted a deformation census of the Middle Route of the South-North Water Diversion Project using Sentinel-1 images. Then, high-resolution images and level data were used to focus on analyzing the deformation results in areas, such as the Jiaozuo and Tianjin sections, verifying the feasibility of InSAR technology in long-span linear water conservancy projects. [PERSON] et al. [33] used PS-InSAR technology to monitor the Middle Route of the South-North Water Diversion Project in Henan Province. At the same time, it has found 20 deformation areas and 7 suspected deformation areas. Those studies further proved the effectiveness of InSAR technology applied to the spatial and temporal variation characteristics of the South-North Water Diversion Project Canal. [PERSON] et al. [34] used ENVISAT ASAR images and the D-InSAR (Differential Interferometric Synthetic Aperture Radar) technique to obtain the deformation monitoring results of the northern section of the South-North Water Diversion Project. It showed that the main reason for the poor stability of this section is the influence of geological and tectonic activities and urban surface subsidence. [PERSON] et al.