A Multi-algorithm Approach of Modeling Coastal Wetland Eco-Geomorphology at the Global Scale

Coastal wetlands such as marshes and mangroves provide vital ecosystem services to the valuable wildlife and large populations living in the coastal regions. With the threats of accelerated sea-level rise, intensified storm surge and salinity intrusion and expansion of infrastructure, many empirical and modeling studies suggested that coastal wetlands may not be able to continue their vital functions and services at the needed levels. However, some high-profile studies published recently argued that by migrating landward, coastal wetlands may retain their habitats throughout this century. To resolve these conflicting results, we developed a 1-D transect-based hydrodynamic model and implemented a multi-algorithm approach within the transect modeling framework to represent four important eco-geomorphology processes (mineral accretion, organic matter accretion, storm surge erosion and landward migration). We validated the model framework comprehensively on both hydrodynamics (inundation, water flow velocity and bottom shear stress) and eco-geomorphology (mineral accretion and organic matter accretion) at three representative sites: a Spartina salt marsh site, a non-Spartina salt marsh site and a mangrove site. Using published data, we also validated the simulated long-term mineral accretion, organic matter accretion, storm surge erosion and landward migration at tens of coastal wetland sites across the globe. Simulations are being used to quantify and understand model uncertainty as a function of tidal range, coastal wetland vegetation and climate.