Rapid Channel Widening Following Weir Removal Due to Bed-Material Wave Dispersion on the River Monnow, Wales

Kentchurch Weir, a low-head weir on the river Monnow, Wales, was demolished in August 2011, releasing a sediment wave that had formed behind the structure for at least a century. We surveyed channel topography and bed-material composition through a 1.5-km long reach prior to weir removal and then periodically over a 2-year period. The fill material was finer than the ambient bed material with all particles mobilized by bankfull flows. Rapid degradation of the 1460-m3 sediment fill in the previously impounded reach occurred as bed material appeared to disperse downstream, consistent with other studies of sediment waves in gravel-bed rivers. The riverbed profile was gradually smoothed through the study reach by degrading...

Categories: Publication; Types: Citation; Tags: flow obstruction, river restoration, riverbed evolution, sediment store