Phinizy researchers to study Savannah River oxbow lakes

Editor’s Note: This article is authored by Oscar P. Flite III, Ph.D., CEO and senior scientist at Phinizy Center for Water Sciences. Flite and his organization are involved in scientific research on the Savannah River that provides critical information needed to make informed decisions about the basin’s natural resources.

phinizy_logoIn 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 shortcut 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 owbow 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.

Shown here, an owbow 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 U.S. Army Corps of Engineers created many oxbows by cutting through wide river meanders. These shortcuts were generally developed in curved areas of river that were too sharp for many of the large commercial vessels to navigate.

The shortcuts 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 shortcuts 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 scientists will perform this oxbow research in collaboration with scientists from Clemson University, Georgia Regents University and Georgia Southern University. The one-year project is being funded by a competitive statewide research competition offered through the South Carolina Water Resources Center at Clemson University.

Results from this research should be available sometime in the spring 2016 and will be presented at the South Carolina Water Resources Conference.

We will also communicate results via Phinizy Center’s website and social media sites. You can follow the progress of this project on our Facebook page.

About US Army Corps of Engineers Savannah District

The U.S. Army Corps of Engineers Savannah District oversees a multi-million dollar military construction program at 11 Army and Air Force installations in Georgia and North Carolina. We also manage water resources across the Coastal Georgia region, including maintenance dredging of the Savannah and Brunswick harbors; operation of three hydroelectric dams and reservoirs along the upper Savannah River; and administration of an extensive stream and wetland permitting and mitigation program within the state of Georgia. Follow us on Twitter @SavannahCorps and on Facebook.com/SavannahCorps
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