Orientation of groins for wide and dynamic lowland rivers

Alluvial rivers at lowland are very complex in nature. Severe bank erosion at high flow and undue sedimentation at low flow are very common there. Groins are not functioning successfully with their present arrangements. This study investigates various orientations of groins to identify the optimum one for the effective functioning at high flow and low flow both. A 2D numerical model, RIC-Nays is utilized upon confirmation through detailed experimental data. Two types of groins: non-permeable and permeable, and four orientations: 100°, 90°, 80° and 70° to the bank line downstream are considered. Computation reveals that smaller angled groins function better through deepening the main channel and minimizing the local scour, except deposition near bank reduces.