Spatiotemporal evolution of land subsidence in coastal reclamation areas: coupling anthropogenic land-use intensity and delayed soft-soil compression

Abstract

This study assesses long-term land subsidence in the Meishan Bonded Port Area, Ningbo, China, by integrating a borehole-constrained three-dimensional geomechanical model, multi-level settlement monitoring, a processed regional PS-InSAR-derived subsidence-rate map for 2022, and land-use intensity (LUI). Delayed soft-soil compression is represented through fixed, site-conditioned equivalent parameter corrections that do not simulate constitutive creep evolution. Spatial LUI is translated into temporally varying equivalent surface-load boundaries. A depth-specific descriptive evaluation at HMG06 and a regional spatial-consistency assessment against the processed 2022 PS-InSAR product show reasonable agreement in layer compression and spatial pattern, while neither comparison constitutes independent full-domain validation. Under the prescribed 2025–2035 baseline scenario, the southern reclamation zone remains the principal subsidence center, and the maximum annual rate decreases from 35 to 40 mm/year in 2025 to 15–20 mm/year in 2035. At the representative southern center, the first soft-soil layer contributes approximately 55%–60% of local modeled compression. Higher LUI-related loading may intensify modeled settlement where developed land overlaps compressible deposits. The results are conditional regional-screening estimates for risk-based planning rather than confidence-bounded forecasts or direct evidence of a specific creep mechanism.