Utilisation of submerged vanes in front of intake ports is an effective approach to address sedimentation in lateral intakes from rivers. Strategically installed, these flow-training structures could increase the mid-depth and near surface flows into the intake, and simultaneously prevent bed-load transport from entering the intake channels. The effectiveness of submerged vanes depends on their number, shape, dimensions and configuration. Determination of optimum values for dimensions or configuration of the vanes is very challenging as the effect of many parameters, which are effective in sedimentation in the intake zone, must be investigated. In this study, effort has been made to determine appropriate dimensions of submerged vanes that are installed in front of a 90 degrees intake from a straight channel. Fuzzy TOPSIS, a multi-objective optimisation method, has been utilised for the optimisation process by considering ten parameters. The simulations have been conducted for three discharge ratios of 0.11, 0.16 and 0.21. The results show that a height of 0.2 times the flow depth, and a length of four times the vane height are the appropriate dimensions for utilisation of submerged vanes in front of the lateral intakes from straight channels.