Bringing New Life to an Eroding Stream

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“In the first section of the creek, we are removing the cattle to find out how taking just cattle out of the equation will improve stream health,” Wynn began. “In the second, we will reshape the stream banks and plant woody vegetation, and in the third, we will use what researchers in the streamrestoration community call natural channel design.”

This last approach, which is also known as form-based design, is the most expensive and involves rebuilding the channel to re-create a functional floodplain and reduce the sheer stress on the stream bank. “We are trying to make a more active floodplain to reduce the force on the stream bank during flooding,” she says, emphasizing that flooding is a beneficial and natural part of the life of a stream. “A
floodplain is like a relief valve. What we are doing is making the Stroubles Creek floodplain rougher by planting more trees and the like.”

Trees are ideal for healthy streams, at least in the easternUnited States. “We believe grasses are not as effective at reducing stream-bank erosion because they lay down during flooding and do not have as extensive or as rigid a root system as woody plants,” Wynn adds.

W. Cully Hession, associate professor of biological systems engineering, has spent the last 12 years studying not only the effects of channel morphology on aquatic ecosystem health but also the effects of trees on stream channels. “Streamside forests are important for stream health,” he says. “The research shows that trees along streams provide many benefits, such as shading, food, improved habitat, and increased bank strength.”

Hession has been involved in the Stroubles Creek project in a study on methods to measure stream-bank erosion rates and the amount of sediment added to streams from eroding channels. In collaboration with Wynn, he is studying how traditional technologies used to monitor stream erosion rates, such as erosion pins, compare with more advanced methods, such as ground-based laser surveying equipment that can map a stream bank by the millimeter.

The stream-restoration research at Virginia Tech involves a variety of other high-tech field equipment, including data loggers, automated samplers, water-quality sensors, a 3-D acoustic Doppler flow meter, and a submerged jet test device. In the Department of Biological Systems Engineering’s Water Resources Lab, a new 16-foot experimental stream channel allows Wynn, Hession, and their graduate students to research how the structure of stream banks, obstacles within them, and vegetation affect water flow and erosion in a controlled setting. They use this equipment to study a range of issues related to stream restoration such as innovative ways to
reduce pollution from urban areas, new sensors for measuring water quality, and techniques for improving stream and wetland restoration design practices.

In many ways, Stroubles Creek has become an excellent outdoor laboratory and classroom that can be used to fulfill Virginia Tech’s missions of research, teaching, and outreach. “There is a push in academia to look at fundamental processes and do process-based stream-restoration designs,” Wynn says. “We are applying this to our stream-restoration work in hopes of finding a more effective and economic way of improving stream channel health.”

For more information about the Stroubles Creek restoration project and similar research, check out the Stream and Wetland Ecological Engineering Team website at http://twosweet.bse.vt.edu/.

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Recirculating Hydraulic Flume
A 16-foot recirculating hydraulic flume allows Wynn and a graduate student to study stream health in a controlled setting.
students measure erosion rates
Other students measure erosion rates at Stroubles Creek.

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