Morphological Controlling Factors of Braided River Reservoir Based on Delft3D Sedimentary Numerical Simulation: Application to Ordos Basin, China

To reveal the regulatory mechanisms and differences in sensitivity of hydrodynamic forces and sediment parameters to the sedimentary evolution of braided river channel bars, this study takes the Sulige Gas Field as a case study and conducts 21 sets of sedimentary numerical simulation experiments using the controlled variable method. The three parameters of discharge, slope gradient, and sediment grain size were fixed, while the target variable was adjusted iteratively. After the river reaches a steady state, quantitative statistics of the area and length-width ratio of 547 identified channel bars are carried out, and sensitivity evaluation is performed by combining principal component analysis and multiple linear regression. The results show that the sedimentary evolution of braided rivers follows a unified evolutionary law, the evolution of channel bars is synergistically regulated by parameter combinations. Under the action of single factors, an increase in discharge promotes the axial extension and scale expansion of channel bars; an increase in grain size enhances the morphological stability of channel bars; slope gradient controls the erosion-deposition balance through gravitational potential energy. The parameter sensitivity is ranked as slope gradient, discharge, sediment grain size.