Experimental investigation of the velocity distribution for a bendway weir

Bendway weirs is a set of structure used to reduce erosion problems at sharp bends of natural stream. Its ability to realign velocity distribution to a better alignment has been proved through previously installed bendway weirs. The effects of different bendway weir's length and degrees of angled downstream were found valuable as a mean to decrease the velocities at the outer bend while not unduly increase the inflow depth. In this study, the effect of different length and different angles downstream of the weirs is presented. The study is conducted in a channel that has been modelled up according to one real bend located in Batang Sadong. Whereby serious erosion at the outer riverbank has caused damages to villages nearby, and even worse especially at flood season. Experiment data shows that, a 3.5cm of bendway weirs angled downstream has successfully realigned the cross section velocities distribution along the bend. High velocities at outer bend have been reduced, cross section velocities were more evenly distributed and acceptable small increment in inflow depth. Thus, a 3.5cm bendway weir with a 20° angle downstream is more effective in velocity redistribution and outer bend erosion elimination