Researchers to monitor Savannah River salinity during harbor expansion
CLEMSON — Clemson University wetland ecologists at the Belle W. Baruch Institute of Coastal Ecology and Forest Science will spend the next year monitoring water salinity levels and vegetation changes at sites in and around the Savannah National Wildlife Refuge.
The research is part of a program designed to evaluate environmental impacts resulting from the Savannah Harbor Expansion Project. It is supported by $360,000 in funding from the U.S. Army Corps of Engineers.
Clemson researcher Jamie Duberstein and his team will install recorders programmed to measure salinity at various depths at hourly intervals, sample vegetation along transects that extend into the heart of the marshes and incorporate satellite imagery as part of a GIS mapping analysis.
They will collect the data at 12 sites located 26 to 30 miles upriver from Fort Pulaski, where the Savannah River Estuary meets the Atlantic Ocean.
The Corps will use the data as a baseline for monitoring the effectiveness of modifications it will make to upper-harbor tidal creeks to alleviate the potential environmental impact of deepening the harbor, including minimizing impact to ecologically unique freshwater tidal wetlands.
“The data we collect will allow the Corps to understand if, after construction of the project, the flow rerouting and other mitigation features are working as intended,” Duberstein said.
The Corps will divert more freshwater into the Back River to minimize the impact of increased salinity in the estuary. Without the mitigation in place, the Corps anticipates 1,117 acres of freshwater tidal wetlands would convert to brackish marsh. With the flow rerouting in place, the Corps anticipates that 223 acres will be converted. Additionally, 740 acres of salt marsh are anticipated to convert to brackish marsh, according to the Corps studies.
The Corps will mitigate for the remaining impact by acquiring and preserving 2,245 acres of freshwater wetlands for the Savannah National Wildlife Refuge at an estimated cost of $12.4 million. The harbor deepening project would acquire lands that the refuge identified as being valuable additions to the habitats they produce and manage, and then transfer ownership of those properties to the U.S. Fish and Wildlife Service.
“We are losing freshwater marshes along the East Coast and the Savannah River contains intact marshes that are environmentally important. We need to keep these marshes as freshwater as we can so this diverse system doesn’t become monolithic. Plant life, wildlife and fisheries would all be negatively impacted by high salinity,” Duberstein said.
Deepening the Savannah Harbor from 42 feet to 47 feet is expected to cost $652 million.
Economic studies project that the harbor deepening will bring $174 million in annual benefits to the U.S. economy and lower transportation costs by allowing larger and fewer ships to move the same amount of goods.
Dredging is slated to begin in 2015 and is expected to take from 48 to 60 months to complete.