Improved modelling of the impacts of sea level rise on coastal wetland plant communities

This study presents an enhanced methodology for modelling the impacts of sea level rise on coastal wetlands. The tool integrates dGPS-calibrated LiDAR data, isostatic uplift and sediment accretion rates to predict the location and extent of plant communities at three non-contiguous micro-topographical coastal wetlands in Estonia by 2100 in response to global sea level rise. Scenarios were run including sediment accretion, elevated sediment accretion and then discounting sediment accretion and dGPS calibration for comparison. Results showed an increase in surface elevation (related to sediment accretion and isostatic uplift) resulting in a decrease in local sea level in the majority of sites and scenarios in the north of the country, although a rise in local sea level is predicted in sites with limited allochthonous sediment supply, predominantly impacting higher elevation plant communities. Wetlands situated on the west coast are likely to maintain equilibrium with sea level as a result of lower sedimentation and isostatic uplift than more northerly sites. This study shows that dGPS-calibrated LiDAR data and sediment accretion are essential to maintain model validity in Baltic coastal wetlands due to their low relief and could considerably improve current sea level rise impact models for other regions.