Figure 1. Map of CTD station, Fripp
Nearshore buoy, and drifter deployment
locations. Original cruise plans were for
drifter release northward closer to St.
Helena Sound, however fuel and time
constraints required early deployment.
Drifter deployment was just over onequarter nautical mile due east of the Fripp
Nearshore Buoy.
Figure 2. Salinity measured at the
Fripp Island NOAA buoy (32.270°N
80.4°W). The historic SC rainfall
ended on 05 October 2015, flowed
down the Edisto River, out St. Helena
Sound, and influenced the nearshore
environment for the next two weeks.
SSU deployed its surface drifters at
the tail end of that flood water
influence on 16 October 2015 (green
line) to track where the waters flowed
and mixed with the coastal ocean.
Figure 3. Section plots derived from the CTD data collected during the drifter
deployment cruise aboard the R/V Margaret Robinson. Top - Southerly (< 32°N)
freshwater plumes were Savannah River outfall. Just north of 32.1°N, off Hilton Head
Island, a clear salt and temperature separation occurred between the southerly
Savannah River water and freshwaters flowing out of Port Royal and St. Helena
Sounds. Port Royal Sound (~32.15°N) is a tidal dominated estuary and did not
contribute significantly to the offshore flood water plume. St. Helena Sound, a mixed or
river-dominated estuary that drains the Edisto River, although not specifically sampled
due to logistical limitations, is the very likely source of surface freshwater plume off
Fripp Island that the Fripp Nearshore Buoy and CTD deployments observed.