I have noticed on my drives to work and to run errands that there is quite a bit of erosion showing up this spring. Several unusually heavy rains combined with prolonged winter freezing and thawing have really affected the landscape, so places that were fine in the past now exhibit gully erosion. Such erosion, once started, continues to move by head cutting upstream, meaning the starting point of the gully continues to move up the landscape. The gully will widen as the side walls slump in. While equipment can be used to smooth out the gully, such land-shaping efforts alone really only put a tiny bandage on a gaping wound. The solution to gully erosion is a grassed waterway.
There are many possible causes of gully erosion, such as land clearing, urbanization, or poor ground cover due to overgrazing or excessive tillage. Grassed waterways force stormwater runoff to flow down the center of an established grass strip, rather than allowing it to erode valuable topsoil. Grassed waterways have a second benefit — the vegetation can filter and absorb some of the chemicals and nutrients in the runoff water. Grass waterways also provide cover for a variety of wildlife.
Sometimes grassed waterways are accompanied by a grade stabilization structure. These structures, which can be made from metal, wood, concrete, or other materials, safely drop the stormwater from the end of grassed waterway into a nearby creek or stream. As the name implies, these structures stabilize the end of the waterway to prevent the gully from re-forming.
Planning ahead will help ensure the new grassed waterway is successful. They work best when the surrounding land that contributes stormwater to the waterway is well managed, otherwise too much sediment will fill up the waterway and it will cease to function. Conservation tillage/no-till, crop rotations, buffer strips, and/or cover crops are common practices used in our area. The waterway may need to accompanied by subsurface drainage as wet soils are detrimental to the establishment of healthy grass. To keep the grass waterway in good condition, lift implements out of the ground, turn off spray equipment when crossing, do not use it as a roadway, fertilize as needed, and mow periodically to avoid woody vegetation and weeds from outcompeting the grass. Waiting until August to mow will benefit ground nesting birds.
Delaware Soil and Water Conservation District has staff with experience in evaluating gully erosion and in designing grass waterways and grade stabilization structures. While this article primarily focuses on the use of grass waterways in the agricultural setting, the practice is also beneficial in residential areas. They are often referred to as grassed swales or bioswales and are usually used to move stormwater away from homes, keeping basements dry and preventing flooding.
For assistance with erosion problems or stormwater issues, please call us at 740-368-1921 or stop by the office at 557 A Sunbury Road in Delaware. Visit us at www.delawareswcd.org and on Facebook.
Bonnie Dailey is deputy director of the Delaware Soil & Water Conservation District. For information, go to www.delawareswcd.org.