Abstract: Building continuous hydraulic lifting dams in small and medium-sized rivers will affect the hydrodynamics and sediment erosion and deposition process of the river. The variation characteristics of river erosion and deposition resulting from different combined operation schemes of hydraulic lifting dams also differ. To address this issue, four typical flood processes were selected for a 2D numerical simulation of water and sediment dynamics in Fenhe River (Erba-Yitang segment) using Delft3D FM model. Under the four operation schemes of hydraulic lifting dam group, the influence of hydraulic lifting dam group on the variation characteristics of erosion and deposition of river channel was analyzed. The findings provide valuable insights for the scheduling of hydraulic lifting dam groups in the midstream of Fenhe River. Results reveal that, under the schemes 1-4 in four flood scenarios, the water depth in front of dam 14^# ranges from approximately 0.5 to 1.4 m, 1.3 to 2.8 m, 0.6 to 1.8 m, and 0.5 to 1.6 m, respectively, at the end of the simulation period. The maximum local velocity behind the dam is approximately 1.5-2.5 m/s, 2.0-6.0 m/s, 2.0-3.0 m/s, and 2.0-2.5 m/s, respectively. The range of erosion and deposition is approximately -0.5 to 1.4 m, -0.3 to 1.9 m, -0.5 to 1.6 m, and -0.5 to 1.5 m, respectively. The total amount of sediment deposition in the river reaches approximately 4.9×10⁴ to 242.3×10⁴ m³, 5.3×10⁴ to 323.5×10⁴ m³, 5.0×10⁴ to 252.5×10⁴ m³, and 4.95×10⁴ to 245.1×10⁴ m³, respectively. The conclusions are as follows: hydraulic lifting dams exhibit the greatest influence on the hydrodynamic field and the change in bed elevation when operating at full capacity. Moreover, the sediment deposition volumes of hydraulic lifting dams are approximately 1.08 to 1.36 times that of non-dam operation under the four flood scenarios.

Key words: erosion and deposition process, Delft3D FM software, hydraulic lifting dam, numerical simulation, midstream of Fenhe River