Assessing potential impacts of sea level rise on mangrove ecosystems in the Mekong Delta, Vietnam

Sea level rise (SLR) due to global climate change negatively impacts coastal zones, in particular wetland and mangrove ecosystems. Mangroves in the Mekong Delta (MD) in Vietnam provide critical ecosystem services in the region; however, escalated relative SLR is likely to affect all ecosystems in the region, with mangroves probably more vulnerable than others. Given the fact that documented information and studies on SLR impacts on mangroves are limited for the region, this study aims to investigate potential changes in mangrove distribution in response to future SLR scenarios in the coastal area in the south of the MD using the Sea Level Affects Marshes Model (SLAMM). Wetland maps for 2013 derived from Landsat 8 OLI sensor, digital elevation model (DEM), and localized site-specific parameters (i.e., subsidence/accretion, erosion, historic trend of SLR, and over-wash) were used as input for the SLAMM to simulate spatial distribution of mangroves under different relative SLR scenarios (i.e., RCP2.6, RCP4.5, RCP8.5, more extreme SLR), and surface elevation change (i.e., subsidence, stable, and accretion) scenarios by the year 2100. Simulation results show that the average annual mangrove losses are likely to be 0.54% and 0.22% for subsidence and stable scenarios, respectively. The findings demonstrate the considerable impacts of SLR on MD mangrove ecosystems and the strong influence of subsidence processes. Inundation was also identified as a main driver responsible for the mangrove loss by the end of this century. Our results are in agreement with findings of other studies at global scales and observed data at regional scales. The results also demonstrate the potential of the approach developed herein for simulating mangrove dynamics under future relative SLR scenarios in the region with acceptable accuracy. The findings from the present study are useful sources for development of proper strategies for minimizing the impacts of SLR on mangrove ecosystems and their vital associated services, to protect and conserve the mangrove ecosystems in the region.