To the untrained eye, the image of a failing stream bank might not look that different from any flowing stream.
Trees form a slight overhanging canopy above the water. Sodden branches lie here and there along the bank. The occasional fallen trunk is spread lengthwise from one side to the other, perfect for kids to tiptoe across, hoping not to slip in and soak their boots in the water.
But within that seemingly typical picture is evidence of a problem that could be a “major threat” to Greenville’s ecosystem as a whole, according to a new study out of Furman University.
Stream bank failure, otherwise known as stream bank erosion, is a naturally occurring process that happens when the force of flowing water exceeds the resisting force of the bank material and vegetation along the stream. Like ocean waves lapping away a beach, the problem can result in the borders of a stream being slowly weathered away.
But the true scale of the problem occurs from the sediment and pollutants that, when eroded away, flow downstream and enter lakes, ponds and other primary water sources. It’s a problem that is exacerbated by development, as the hard-paved surfaces of cement and asphalt offer little chance for rainwater to be absorbed into the ground as it naturally would before entering streams, thus increasing the flow of the water and the extent of erosion.
Now a study aims to determine the scope of that erosion. Conducted by Libby Dixon of Furman University, in partnership with Friends of the Reedy River, the study strived to find where stream bank failures were most prevalent and what could be done to abate the problem.
“Stream bank failures are a major threat to larger bodies of water and the environment around them,” Dixon wrote. “Streams are important aspects of ecosystems all around the world, and they must be protected to ensure a properly functioning system.”
Rather than comb through every swath of wilderness and waterway in the county, Dixon relied primarily on crowdsourced and publicly accessibly data — watershed boundaries, parcels and zoning, and monitoring station layers — to conduct the study. She sought not only to locate failing stream banks, but also to identify the key characteristics of those stream banks, primarily the water level and type of failure.
“The results show that the majority of failing stream banks recorded through the survey are on privately owned land,” Dixon concluded.
In addition, she found that while there are some water quality monitoring stations in the county, with data available online through the South Carolina Department of Health and Environment Control, they didn’t appear to accurately pick up on the changes in the stream that she herself was able to track.
“Both of these factors make restoration of failing banks difficult because property owners may not be aware of the bank or the damage it can cause if it fails,” Dixon wrote. “The results indicate that private lands need more awareness of failing stream banks’ causes and effects as well as a reevaluation of monitoring stations in the county.”
But rather than simply outlining the problem, the study also offered a model by which conservation groups could begin the process of restoration. Even stream bank failures on private land could be restored with landowner approval, a notion Dixon saw as mutually beneficial for the landowner and those concerned about the broader impact on the county’s ecosystems.
“This survey is something that can be used for years to come,” Dixon wrote. “Using layers provided by Greenville County, land ownership and zoning can easily be identified which helps organizations know where to allocate resources and which areas of Greenville need the focus.”