The hydraulic effects of the weirs reduce erosion on the outer bank of the bend by reducing flow velocities near the outer bank, reducing the concentration of currents on the outer bank of the bend, and producing a better current alignment through the bend and downstream crossing. In addition, the Bendway Weir is able to solve many stream alignment problems while simultaneously improving aquatic and stream corridor habitat.
In a typical unimproved bend (without Bendway Weirs), surface water currents tend to move from the inside of the bend toward the outside, concentrating flow and increasing velocities along the outer bank of the bend. These higher velocities can lead to increased bank erosion.
With the use of Bendway Weirs, water flowing over the weir is redirected at an angle perpendicular to the axis of the weir. The stream's strong secondary currents in the bend are broken up.
With the weirs angled upstream, flow is directed away from the outer bank of the bend and toward the point bar (inner part of the bend). This redirection of flow not only occurs at stages slightly higher than the weir crest but at all higher stages. Emergent weirs act as spur dikes.