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

Abstract

Featured Application: This study employs time series Interferometric Synthetic Aperture Radar (InSAR) techniques to conduct high-precision monitoring of land subsidence in reclaimed urban areas of Tianjin’s Binhai New Area, and analyzes the influence of different land cover types and their dynamic changes on settlement patterns. The findings provide a scientific basis and technical support for infrastructure protection, sustainable spatial planning, and policy formulation in coastal reclaimed regions. Global coastal reclamation areas face significant land subsidence, threatening infrastructure and sustainable development. China’s large-scale projects show particularly severe subsidence. For example, Tianjin’s Binhai New Area contains 413.6 km2 of reclaimed land, and subsidence is driven by soft soil consolidation, industrial loads, and dynamic land use changes. This study addresses the unique geology of coastal reclamation zones: thick, soft clay layers; high porosity; and low soil strength. We employed optimized Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technology using 48 Sentinel-1A radar images (2019–2022), which generated high-resolution annual deformation rate maps revealing a north-high, south-low subsidence gradient. Crucially, validation against leveling data confirmed reliability. The systematically quantified results demonstrate built areas and the bare ground intensifies subsidence through structural loads and soil compression. Land use transitions also exacerbate differential settlement. For coastal cities and reclamation zones, key strategies emerge, including regulating structural loads in high-subsidence areas, managing soft soil consolidation, and implementing dynamic monitoring. Aligning development intensity with geological capacity is essential, and adopting adaptive spatial planning can mitigate subsidence hazards. This approach offers a scientific framework for enhancing global coastal resilience.