INVESTIGATING THE TRANSITION FROM FRESHWATER TO SALTWATER WETLANDS IN SOUTHEASTERN NORTH CAROLINA USING GIS, REMOTE SENSING, AND STATE-AND-TRANSITION SIMULATION SOFTWARE

Relative sea-level and predicted rate of sea-level rise can impact sedimentation patterns, tidal regime, and elevation in coastal wetlands which influences wetland stability, species presence, and the transition of one wetland type to another or loss of wetlands to open water. The transition/loss of coastal wetlands may increase susceptibility to flood inundation and shoreline erosion. The purpose of this project is to use decadal historic aerial photography from the 1950s through 2000s, recent satellite imagery, other geospatial data, and field data to investigate wetland transitions at two tidal creeks in the Cape Fear River, in southeastern North Carolina. Results have provided evidence documenting the wetland transitions. Notably, areas previously dominated by bald cypress (Taxodium distichum) have transitioned to emergent wetlands. Earlier studies that have hypothesized that coastal marshes have changed because of a changing salinity are now confirmed with the results from this project: the previously freshwater environments are now brackish salinities, are experiencing larger tidal amplitudes, and the types of vegetation have changed. Further analysis will quantify the rate and type of wetland transition and along with other biophysical variables (e.g. elevation, land cover and salinity) will be used to predict future wetland conditions using state-and-transition simulations (ST-SIM) through 2100 under increased relative sea-level predicted to be 0.3m to 2.5m.