The bendway weir method involves the installation of a series of low rock structures at the bend of an eroding stream channel. Streambank erosion is a sign of significant changes in land uses over the years, Frazee said. It is the result of urban development, the straightening and channelizing of creeks and streams, as well as the conversion of land into erosive rowcrops of corn and soybeans. As streams are straightened, water flow builds up speed. In fact, he said, many Illinois streams have made the Jekyll to Hyde transformation from a gentle, meandering flow to raging torrents capable of causing major destruction.
Bendway weirs are a simple and affordable way to hold one's ground.
In an untreated bend, the faster moving water flows near the outer bank. By adding a series of low rock structures angled upstream on the outside bend of an eroding stream channel, you can redirect this high-velocity flow away from the eroding bank toward the center of the channel. These stone structures work, said Frazee, because when water passes over the top of the bendway weir, it is redirected at right angles to the crest of the weir. Because the weirs are slanted upstream, water angles away from the streambank. By using a series of bendway weirs, the water flow is redirected through the eroding bend by each weir until the water flow is stabilized.