Phinizy Researchers to Study Savannah River Oxbow Lakes

By: Dr. Oscar Flite, III

In order to make sure there is enough water to support a healthy river ecology and thriving economies along the Savannah River, water resource managers are always in need of high-quality information that will allow them to make better decisions so they can provide the balance between ecology and economy.  This spring, Phinizy Center scientists will begin a study to  examine the impact of various flows on the aquatic life in oxbow lakes found along the Savannah River downstream of Augusta.

Oxbow lakes are remnant sections of river channels that have been cut off from the main river flow. These remnant sections are created naturally in lowland rivers as a result of erosional processes where a narrow strip of land is surrounded by water on three sides.  Over time, the river erodes both sides of the land creating a short cut and leaving a section of old river channel. This channel or oxbow is initially connected to the river via surface water but over time can become disconnected and filled as a  result of sediment transport and deposition.

Shown here, an oxbow lake (left) and soon-to-be-oxbow lake. Oxbow lakes are remnant sections of river channels that have been cut off from the main river flow. (Courtesy photos)
Shown here, an oxbow lake (left) and soon-to-be-oxbow lake. Oxbow lakes are remnant sections of river channels that have been cut off from the main river flow. (Courtesy photos)

Research on oxbows around the world has revealed their important role in supporting healthy rivers. Studies have shown many more algal, zooplankton, mussel and fish species live in oxbows compared to the adjacent river.  Other studies have indicated that oxbow lakes are essential to the health of the river fisheries, providing abundant food resources and essential nursery habitat for juvenile fish.

In an effort to straighten and shorten the Savannah River for commercial navigation, the Army Corps of Engineers created many oxbows by cutting through wide river meanders.  These short cuts were generally developed in curved areas of river that were too sharp for boats to navigate. The short cuts were created by dredging a new river channel through a small strip of land that the river ran along both sides of, much like the natural oxbow creation process. From the 1950s to the 1970s, a total of 37 navigation short-cuts were completed, shortening the Savannah River by about 40 miles.

The oxbow research will involve several components.  First, scientists will assess the connectedness of many of the oxbows between Augusta and Savannah using high-accuracy GPS survey equipment.  Next, they will monitor surface and groundwater levels in four oxbows, two that are still connected to the river by surface water, and two that are disconnected.  Then, Phinizy scientists will monitor water quality and analyze water samples for nutrient, algae, and zooplankton levels.  Lastly, the researchers will periodically examine the fish communities in these oxbows.  Perhaps most interestingly, some fish in one connected oxbow will be outfitted with tiny radio tags that will allow researchers to monitor their movements between the river and the oxbow.

Phinizy Center scientist will perform this oxbow research in collaboration with scientists from Clemson University, Georgia Regents University, and Georgia Southern University.  The project is being funded by a competitive statewide research competition offered through the South Carolina Water Resources Center at Clemson University; the project will last for one year.  Results from this research will be presented at the South Carolina Water Resources Conference and communicated via Phinizy Center’s web and social media sites.