WIND DRIVEN SALINITY DISTRIBUTIONS IN THE EMILY AND RICHARDSON PREYER BUCKRIDGE COASTAL RESERVE, SOUTHERN ALLIGATOR RIVER ESTUARINE SYSTEM, EASTERN NORTH CAROLINA

The Emily and Richardson Preyer Buckridge Coastal Reserve is a low-lying, peatland-dominated freshwater wetland at the southern end of the Albemarle-Pamlico peninsula, Tyrrell County, eastern North Carolina. Drowned tributaries of the Alligator River estuarine system, the Frying Pan and Alligator River, surround the Reserve. Over the past century, the hydrology of the Reserve has been altered by the construction of a canal network that was dedicated to facilitating timber harvest and draining of adjacent agricultural lands. Brackish conditions observed in the canal network and groundwater system of the Reserve have been linked to saltwater intrusion emanating from the Alligator River. The purpose of this study was to determine the extent and mechanism of saltwater intrusion in the groundwater and surface water systems of the Reserve. Water levels, temperature, electrical conductivity (which was used as a measure of salinity) and weather data were used to assess the hydrology in the Reserve. The mechanism responsible for variations in salt concentrations was investigated by assessing spatial and temporal distributions of electrical conductivity. Results reveal that salinity levels in the Alligator River were more elevated under the influence of strong northerly winds. A change in the wind direction from north to south appeared to trigger the inflow of salt plumes into the canal network. The inflow typically occurred when the wind intensity was at least 10 mph. However, canals directly connected to the Alligator River appeared to be the most sensitive to changes in wind direction and intensity. The groundwater data revealed that salinity levels were higher in the south of the Reserve than in the north, and that there was generally less variability of electrical conductivity in groundwater than in surface water. The presence of the Intracoastal Waterway and variable winds appear to be the driving mechanism that controls salinity levels in the Alligator River and the Reserve. Any strategies for restoration and management should therefore account for the mechanisms that influence saltwater intrusion in the Reserve.