River Bed Sediment Management by the Winged Bandal-Like Structure and Selection of Optimum Structure Using Ranking of SAW and TOPSIS Methods

Abstract

This experimental study investigated the physical model of a 180-degree river bend to introduce a new measure called as winged bandal-like (WBL) structure for river bed sediment management. The new structure is a combination of bandal-like (BL) and triangular vane structures. Nine different alternatives of the WBL structure, including three dimensionless vane effective lengths and three different vane angles, were tested in non-submerged and clear water conditions. A total of 18 attributes were then defined in accordance with the resulting river bed scouring and deposition. The multiple-attribute decision-making, simple additive weighting, and TOPSIS methods were employed to rank the alternatives. Baseline tests were also carried out for the BL and the impermeable spur dike (ISD) structures under similar flow conditions. Results revealed that the maximum scour depth, as the main cause of failure around the considered WBL structure, decreased by 31% compared to the scour around the ISD. The maximum deposition height behind the considered WBL structure showed an increase of 47% and 96% in comparison with ISD and BL structures, respectively. In the WBL structure, a longer, better-shaped sedimentary stack was developed along and close to the outer bank.