Laboratory Study of Bendway Weirs as a Bank Erosion Countermeasure

Abstract

AbstractBendway weirs are linear structures similar to spurs but designed to be overtopped by typical streamflows, and have recently attracted attention as an environmentally sensitive means of protecting the outer banks of stream bends. A laboratory study was conducted to examine the effectiveness of these type of structures, constructed following FHWA (U.S. Federal Highway Administration) design-manual guidelines, in protecting the outer bank of a 90° bend in a narrow channel with both erodible bed and banks. Experiments were performed at a single nominal (initial) depth, and so characterized by a single (initial) ratio of radius of curvature to top width of 3.3, with and without a field of five weirs. Measurements of erodible boundary elevations as well as the magnitudes of the time-averaged point horizontal velocities at various cross sections were taken. Although a definite overall deflective effect by the weirs was observed, the outer bank remained susceptible to significant erosion even in the pres...