Assessing Two-Decade Coastal Sea-Level Rise Trends in the Mekong Delta, Vietnam Using Multi-Mission Satellite Altimetry

Sea level rise due to thermal expansion of the ocean and melting Arctic ice poses a serious threat to low-lying coastal areas such as the Mekong Delta (MD), Vietnam. This study will assess sea-level rise trends in the coastal region of the Mekong Delta over two decades (2005–2024) based on various types of satellite altimetry data. The authors utilized 147,352 sea surface height (SSH) points from five types of altimetry satellites (Envisat, Saral/AltiKa, CryoSat-2, Sentinel-3A, Sentinel-3B) and applied the cross-over adjustment method to eliminate the time-varying dynamic sea surface height component (h _t ). This allowed for the construction of mean sea surface (MSS) models for four consecutive five-year periods (2005–2009, 2010–2014, 2015–2019, 2020–2024). Eight representative locations across the study area were selected, and a simple linear regression method was used to determine the local sea-level rise rate for the study region. The results indicate that the average sea-level rise rate for the study area is 3.92 mm/year. This finding is consistent with sea-level observations from tide gauge stations in the region (3.73 mm/year), thereby affirming the feasibility and effectiveness of applying altimetry data in assessing sea-level rise trends. The research findings will provide a solid scientific basis for climate change adaptation planning in the Mekong Delta