Monitoring land subsidence with InSAR in Amsterdam Rijnkanaal

The Amsterdam–Rijnkanaal is a critical inland waterway linking the port of Amsterdam with the River Rhine and the European hinterland. Recent hydrogeological monitoring has revealed signs of canal seepage toward adjacent polders, contributing to the development of seepage wells that . may be altering the hydrogeological equilibrium of the area. Additionally, long-term land subsidence may reduce the thickness, and thus the weight, of the surficial soil layers that resist upward pore-water pressures from the underlying sand layer. Understanding the extent and cause of these localised seepage wells and effects of land subsidence processes is essential for infrastructure safety and long-term maintenance of the canal. This feasibility study investigates the potential of satellite-based Interferometric Synthetic Aperture Radar (InSAR) to detect and monitor ground deformation along the Amsterdam–Rijnkanaal between 2019 and 2023. Open-access Sentinel-1 data from the European Ground Motion Service (EGMS) were analysed and integrated with geological (GeoTOP), hydrological (BRO piezometers), and model-based subsidence predictions (from both Waternet and Deltares Atlantis model). All data were harmonized in space and time to enable direct comparison of observed and modelled deformation patterns. The results show that InSAR provides consistent and spatially coherent deformation measurements in areas of high radar reflectivity, particularly along infrastructure and built-up areas. In contrast, vegetated and agricultural areas were seepage wells likely occur exhibit sparse InSAR coverage due to their low reflectivity. Average subsidence rates along the Amsterdam–Rijnkanaal are approximately –1 mm/year, with localized hotspots reaching up to –10 mm/year near major infrastructures. These patterns generally agree with natural subsidence predicted by the Atlantis model, compatible with areas prone to peat oxidation and soft-soil compaction, while few isolated zones show higher deformations possibly linked to canal seepage or local geotechnical variability. However, the InSAR measurements investigated in this study cannot demonstrate whether zones of higher deformation coincide with seepage-well locations, or if deformations are in any way related to seepage activity. Overall, this study demonstrates that InSAR is a valuable tool for detecting and characterizing deformation around the Amsterdam–Rijnkanaal, but its capabilities in vegetated areas where seepage wells likely form are currently limited. Future work can improve the capabilities of InSAR in rural area by installing, for example, corner reflectors in specific areas of interest. More investigations are also need to prove the link between subsidence and seepage activity.