FLORIDA GULF COAST MARSH SURFACE ELEVATION TABLE MESUREMENTS

Florida Gulf Coast marshes along the Big Bend are experiencing sea-level rise and an insufficient sediment supply to maintain the marshes surface elevation. Local mean sea level is rising at an approximate rate of 1.5 to 2.4 millimeters (mm) per year and the spring-fed or controlled (dammed) rivers of the Florida Gulf Coast do not provide sufficient sediments to maintain long-term health of the marshes. Marsh health is determined by several factors; sediment supply, sea-level rise, storm events, erosion rate of waves and marsh subsidence. Over the last 10 years, the Florida Geological Survey’s Coastal Research Program, in cooperation with the United States Geological Survey, installed Surface Elevation Tables (SET) at a number of river sites along the Florida Gulf Coast to measure elevation changes of the marsh surface. SET measurements were combined with feldspar marker horizon measurements to quantify changes in marsh topography. Due to the sediment starved nature of these marshes (-0.3 to -15.0 mm/year) and the inability to keep pace with sea level rise, the Big Bend coastal areas are at risk, documenting the dynamic and mobile nature of coastal environments.