The sedimentation basin is an important part of hydraulic engineering. Because the prototype size is too large and not easy to analyze, Mike 21 has the advantages of easy input, conversion, analysis, and demonstration of data results, which are flexible and convenient; however, this method has not been used in hydraulic engineering by previous researchers. This research used the sedimentation basin of the Yellow River Diversion Project as the research object, and a simulation model of the sedimentation basin channel #1 was developed using Mike 21 software to analyze its water and sediment characteristics and conditions in different periods. Using numerical simulation methods, three types of sedimentation basin operation schemes were targeted, the sedimentation changes and sedimentation law of channel #1 were evaluated in each scheme, and the sedimentation effects were compared. The results show that in conditions of different incoming water and sediment and diversion timings during the flood and non-flood seasons, the sedimentation basin adopts an operation scheme to lower the outlet water level, and the siltation volumes are 180,000 and 150,000 m³ lower than the high-outlet water levels, respectively. Moreover, its siltation status is significantly improved, which can effectively extend the service life of the sedimentation basin, prolong the period of silting removal by about 3.5 months, and provide a scientific basis and reference for the optimization of the operation mode of the sedimentation basin in other types of hydraulic engineering.

The change of water and sediment conditions in wandering channels has a great impact on the stability of river regime. The quantitative relationship between them is still unclear. The qualitative influence of water and sediment conditions on the river regime stability was analyzed by a model test. The response relationship between the upward or downward moving distance of the main stream zone and water and sediment conditions was quantitatively studied by using the measured water and sediment data and large-section data over the years. The results showed that when the upstream water and sediment inflow conditions change, the stability of a wandering channel with relatively stable river regime under the control of finite boundary will still change. When the river channel is at 1000 m³/s under the action of long-term small water, or silting thickness is about 0.53 m, the main stream next to the project moves upwards about 1170 m along the way. In the case of a large flood, such as 8000 m³/s, or scouring depth is about 0.39 m, the main stream next to the project moves downwards about 870 m along the way. The study provides a certain scientific basis for river regime stability and river flood control early warning, and provides a certain method reference for quantitative study of river regime evolution of other rivers at home and abroad.