Effects of Sea Level Rise on Salinity Intrusion in St. Marks River Estuary, Florida, U.S.A.

Effects of sea level rise on salinity intrusion in St. Mark River estuary has been investigated by the application of a 3D hydrodynamic model. The estuary receives freshwater inputs from two upstream tributaries, Wakular River and St. Mark River. The model has been calibrated by using the observed data measured in the estuary. Under the sea level rise of 0.85m, numerical modeling under the flow for the 4-month period in 2000 indicate that, the sea level rise can cause substantial increase of salinity near the lower Wakulla River, with the increase of 9.2 ppt for surface salinity and 12.7 ppt for bottom salinity. At mid estuary, surface salinity increases by 5.6 ppt, and bottom salinity increases by 3.8 ppt. Because the existence of freshwater and brackish marshes through much of the Wakulla River, the substantial increase of salinity by sea level rise of 0.85 m may have significant impact on the ecosystem in Wakala River tributary.