Author(s): Qin Lu, Qingchao Guo, Hongling Shi, Anjun Deng
Linked Author(s): Qingchao Guo, Hongling Shi
Keywords: Non-equilibrium sediment transport; Desilting basin; Mathematical model; Deposition rate;
Abstract: Desilting basins are usually set followed the heads of diversion projects to deposit the coarse particles in the diversion flow. Based on a one-dimensional non-equilibrium sediment transport theory, a mathematical model of the sediment deposition was established in this study. The proposed model could not only calculate the sediment deposition rates in the desilting basin, but also profile the sedimentation distributions along the desilting basin, as well as the deposition rates of each particle size grades, and the changes of suspended sediment concentrations and gradations. The model was applied to calculate the characteristics of sediment deposition in a desilting basin in the Central Yunnan Water Diversion Project. The results showed that the silting thicknesses were lager near the inlet cross-section and gradually decreased smaller to the outlet cross-section; the suspended sediment integrated deposition rates were approximately 35%, in specific the coarse particles (greater than 0.05 mm) deposition rates were between 87.08% and 90.91%, that lead to the particles greater than 0.05 mm at the outlet cross-section left only between 4.50% to 6.29%. Furth more, In order to figure out the effects of different desilting basin scales on the deposition rates, three design schemes were put forward, including lower or raising the bottom level of the desilting basin by 2 m and extending the desilting basin by 50%. The results showed that in case of the finer suspended sediment (median particle size of 0.0153mm) in the flow, the different scales of the desilting basin had no significant effects on the overall sediment deposition rates, except the particle sizes greater than 0.05 mm.