URBANA, Ill. – In rural areas, slow-moving, peaceful streams can become raging torrents quickly during heavy rains. The curved meanders of streams naturally slow water current, says Duane Friend, University of Illinois Extension energy and environment stewardship educator. Rapidly moving water erodes streambanks. Though erosion is a natural process, excessive soil loss creates problems.
"During high flow periods, most erosion occurs on the outside bend of a meander where the fastest and deepest flow occurs," Friend says, "cutting into cropland or other areas."
Illinois Extension outlines the following methods for controlling erosion, based on geometry and flow of the stream:
- Willow-Post Method: Plant dormant, native willow cuttings to stabilize eroding streambanks. This method provides protection in watershed areas of 25,000 acres or less.
- Bendway Weirs: Angle rock-covered structures upstream to direct water away from the outer bank. Weirs are anchored into the base of the streambank to prevent floodwater from cutting behind the installed weir.
- Stone Toe Protection: Place a continuous stone dike along the toe or bottom of the eroding bank and attach anchors perpendicular to the stone to prevent floodwater from cutting behind the rock.
- Rock Riffles: Construct alternating, regularly spaced, deep and shallow areas called pools and riffles to simulate normal stream flow. The rock riffles provide the proper grade stabilization and the pools allow for dissipation of energy from the flowing water.
- Stream Barbs: Angle stream barbs upstream, similar to bendway weirs, but at a much more severe angle. The stream barbs work more aggressively than the bendway weirs by redirecting the flow of the water away from the eroding bank.
SOURCE: Duane Friend, Energy and Environment Stewardship Educator, Illinois Extension
WRITER: Judy Mae Bingman, Communications and Marketing Manager, Illinois Extension
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