As the longest water transfer route in the world, the South-North Water Diversion Project (SNWDP) plays a key role in mitigating the serious water shortage problem in the arid north China, and thus the routine stability monitoring of this mega infrastructure becomes a critical issue to ensure continuous fresh water supply. Compared with traditional geodetic tools such as leveling and GNSS that can only measure deformation at discrete points along the canal, modern satellite Synthetic Aperture Radar Interferometry (InSAR) that can capture subtle ground deformation over wide areas is much more suitable to accomplish this challenging task. In this study, we carried out multi-scale InSAR analyses with multi-track Sentinel-1 data stacks to monitor deformation along the Middle Route canal of SNWDP. A coarse-resolution InSAR analysis was first carried out to map regional land subsidence in north China, and the result suggested that the Middle Route canal bypassed the huge subsidence funnel in the southeast part of Hebei province and exhibited overall stability. Afterwards, the results of relatively high-resolution InSAR analyses performed within the 5 km buffering zones along the entire canal revealed that a few sections were affected by significant embankment deformation or land subsidence. In particular, the high-filled canal sections are more prone to deform, such as the cases in Ye County and Jiaozuo City in Henan province. The validation of InSAR deformation measurements with synchronous leveling in Jiaozuo City indicated that a measurement accuracy of 6 mm was achieved. Another big problem identified is the severe uneven land subsidence along the Tianjin Branch Route, which may pose great threats upon the long-term safety of local water transfer operation, and must be handled properly to avoid further degradation.

作为世界上最长的输水路线，南水北调工程（SNWDP）在缓解北方干旱地区严重的水资源短缺问题方面发挥着关键作用，因此，对这一大型基础设施进行例行的稳定性监控变得至关重要问题，以确保持续的淡水供应。与传统的大地测量工具（例如水平仪和GNSS）只能测量运河离散点的变形相比，现代卫星合成孔径雷达干涉仪（InSAR）可以捕获大范围的细微地面变形，因此更适合完成这项艰巨的任务。在这项研究中，我们使用多轨Sentinel-1数据堆栈进行了多尺度InSAR分析，以监测SNWDP中线沿运河的变形。首先进行了粗分辨率的InSAR分析，绘制了华北地区的地面沉降图，结果表明，中线运河绕开了河北省东南部的巨大沉降漏斗，表现出整体稳定性。此后，在整个运河的5 km缓冲带内进行的相对高分辨率的InSAR分析结果表明，一些路段受到了明显的路堤变形或地面沉降的影响。特别是在河南省叶县和焦作市，高填方运河段更容易变形。焦作市同步调平InSAR变形测量结果的验证表明，测量精度达到了6 mm。