Treffer: Challenges in comparing land subsidence measurements by PS-InSAR with simulations from coupled hydro-geomechanical modelling: a case study in Antwerp Harbour

Land subsidence is a serious problem in rapidly urbanizing areas like Antwerp, Belgium, where one known driver is the consolidation of Holocene sediments beneath the harbour’s backfill. However, the potential contribution of groundwater abstraction to subsidence remains poorly understood, as deformation measurements from interferometric synthetic aperture radar (InSAR) alone cannot pinpoint subsurface processes. This study addresses this gap by investigating whether groundwater-induced consolidation also plays a role in subsidence in Antwerp Harbour. In this work, deformation estimates derived from persistent scatterer InSAR (PS-InSAR) and a 3D-MODFLOW groundwater flow model, sequentially coupled to a 1D-geomechanical model implemented in Python. The model captures delayed consolidation in low-permeability units.For modelling, a region outside the harbour’s backfill was selected to exclude the influence of harbour sediment consolidation and isolate the potential role of groundwater abstraction, comparing observed and simulated deformations. Results show groundwater-induced consolidation contributes to subsidence rates of 1.78 mm/year (2009–2016), closely matching PS-InSAR estimates of –2.67, –2.39 and –2.43 mm/year from SkyGeo (2017–2022), EGMS (2019–2023), and TerraSAR-X (2019–2022), respectively. Validation of the PS-InSAR datasets was performed using GNSS station BEZA, with the EGMS showing the best fit. Results reveal groundwater level changes contribute to subsidence beyond natural sedimentconsolidation, although challenges such as data scarcity complicate direct comparisons. The insights point to groundwater as a likely additional factor in regional subsidence and emphasize the importance of improved data integration for refining hydro-geomechanical models to enhance subsidence predictions.
BRAIN-Belspo project LASUGEO, Monitoring LAnd SUbsidence caused by Groundwater exploitation through gEOdetic measurements