Sea-Level Rise Effects on Hurricane-Induced Salinity Transport in Apalachicola Bay

Salinity is an important indicator for estuarine ecosystem. Estuarine salinity can be affected by hurricane and sea-level rises. In this study, hydrodynamic modeling study has been conducted to investigate the effects of sea-level rise on hurricane-induced salinity in Apalachicola Bay. By using the dataset for the Hurricane Dennis occurred in July, 2005, model simulations were conducted under different sea-level rise scenarios. Results from model simulations show the effects of sea-level rise on the estuarine salinity transport during different phases of the storm surge. Generally, the increase of water level by either storm surge or sea-level rise results in the intrusion of majority saline sea water from the east to the west through East Pass. Salinity at two oyster bars responds to the storm surge and sea-level rise differently because Cat Point is located in the east and Dry Bar is in the west of the river mouth. In Cat Point, sea-level rise can cause substantial increase of salinity because it is located between the river mouth and East Pass. Salinity at the peak of the storm surge reaches 30 ppt even without sea-level rise. While salinity at the end of the storm surge reduces to about 20 ppt under no sea-level rise condition at Cat Point, it substantially increases to 30 ppt in response to a sea-level rise of 0.2 m. However, in Dry Bar, salinity is less sensitive to the sea-level rise and the storm surge. At the peak of the storm surge, salinity in Dry Bar is 30 ppt, 28 ppt, 30 ppt., under SLR 0.2 m, 0.5 m, and 1.2 m, respectively. However, near the end of the storm surge, salinity is 22 ppt, 22 ppt, and 27 ppt under 0.2 m, 0.5 m, and 1.2 m SLR conditions, respectively. This indicates that, after the storm surge, salinity in Dry Bar can recover to the normal range (below 26 ppt) if sea-level rise is less or equal to 0.5 m.