Monitoring Large-Scale Hydraulic Engineering Using Sentinel-1 InSAR: A Case Study of China's South-to-North Water Diversion Middle Route Project

The Middle Route of South-to-North Water Diversion (SNWD) Project,known as one of the greatest hydraulic projects of China, undertakes most of domestic and industrial water use in the Beijing–Tianjin area, as well as a part of ecological water use. The whole canal should be monitored to ensure a continuous water supply for water-receiving areas. Compared with traditional ground-based monitoring tools limited by the low distribution density, intensive labor force, and huge cost, the satellite synthetic aperture radar interferometry (InSAR) with wide coverage, high-frequency revisiting, and low cost is more suitable for monitoring large-scale infrastructures. In this study, we employed the Sentinel-1 data to monitor the canal of the Middle Route of the SNWD Project within Henan Province. The deformation rates along the canal were obtained by using persistent scatterer InSAR, from which a total of 20 deformed canal sections and seven suspected deformed canal sections were identified. Among them, the Shahe aqueduct is overall stable except for the Shahe Beam Aqueduct and Lushanpo Landing Aqueduct. The Yuzhou-Changge canal passes through a subsidence funnel with a maximum deformation rate of about –20 mm/year. The InSAR-derived deformation coincides well with the
in-situ
leveling measurements over the Yuzhou-Changge canal. Their correlation is 0.95 and the root mean square error of their differences is 2.41 mm/year. The results demonstrate the effectiveness of satellite InSAR for monitoring large-scale hydraulic engineering. It can be combined with ground leveling to achieve overall investigations and detailed monitoring, largely improving the efficiency and cost of the current ground monitoring system.