Analysis of Surface Deformation and Its Relationship with Land Use in the Reclamation Land of Tianjin Based on Time-Series InSAR

Global coastal reclamation areas face significant land subsidence threatening infrastructure and sustainable development. China’s large-scale projects show particularly severe subsidence. Tianjin’s Binhai New Area exemplifies this challenge with 413.6 km² of reclaimed land. Subsidence here is driven by soft soil consolidation, industrial loads, and dynamic land use changes. This study addresses coastal reclamation zones’ unique geology: thick soft clay layers, high porosity, and low soil strength. We employed optimized SBAS-InSAR technology using 48 Sentinel-1A radar images (2019–2022). This generated high-resolution annual deformation rate maps revealing a north-high, south-low subsidence gradient. Crucially, validation against leveling data confirmed reliability (RMSE = 5.70 mm, correlation > 0.95). Systematically quantified results demonstrate built areas and bare ground intensify subsidence through structural loads and soil compression. Land use transitions also exacerbate differential settlement. For coastal cities and reclamation zones, key strategies emerge. These include regulating structural loads in high-subsidence areas, managing soft soil consolidation, and implementing dynamic monitoring. Aligning development intensity with geological capacity is essential. Adopting adaptive spatial planning can mitigate subsidence hazards. This approach offers a scientific framework for enhancing global coastal resilience.