Estimating vertical land motion-adjusted sea level rise in a data-sparse and vulnerable coastal region

Abstract

Sea level rise (SLR), driven by global warming, threatens coastal Bangladesh through inundation, land loss, and displacement. However, SLR estimates are often inconsistent or overestimated due to limited data and inadequate correction for vertical land motion (VLM). This study presents an integrated approach to accurately assess SLR by combining multi-station tide gauge (TG) records with satellite altimetry (SA) and interferometric synthetic aperture radar (InSAR) data across Bangladesh’s coastline. Relative SLR (RSLR) rates were derived from TGs, absolute SLR (ASLR) from SA, and InSAR-derived VLM trends were used to correct TG-based estimates. Results revealed strong seasonal variations, with sea levels peaking in April and lowest in September. Decadal trends indicated alternating phases of rise and fall. Annual SLR rates averaged 5.40 mm/year from TGs and 4.94 mm/year from SA, with notable spatial variations. VLM analysis showed subsidence at five TG sites and uplift at six. After VLM adjustments, all stations exhibited positive ASLR trends, averaging 4.58 mm/year. This study demonstrates that incorporating VLM and corrections of TG records significantly improves SLR estimation. The findings provided critical insights into the spatial and temporal dynamics of sea level change and provide a scientific basis for climate adaptation and infrastructure planning in Bangladesh’s vulnerable coastal zone.