<p>Turbidity currents transport sediment from the continental margin to the deep-sea. These currents are influenced by topographic forcing, which introduces an essential additional force crucial for the momentum balance that governs the morphodynamic evolution and architectural configuration of the channel system. However, there is a paucity of research on the dynamics of turbidity currents under additional forces, especially regarding the transportation and deposition of sediment at meander bends through secondary flows. It is ideal to study the additional forces acting on submarine channel flows in the Yinggehai Basin, northwestern South China Sea, as this region contains two types of channels with different sinuosity and additional forcing induced by channelized complexes. Numerical models involving particulate-driven flow are employed to explore different nonlocal accelerations caused by topographic forcing within the sinuous channels in the study area. The results show that nonlocal acceleration and tight bends can change the flow structure of the channel systems, leading to a reversal of the secondary circulation, and an increase in super-elevation, overspill, and the overall radial material flux. The secondary flow controls the morphological evolution of the channels. A general model is proposed to explain the range of secondary flow structures and the corresponding sedimentation patterns observed concerning different additional forcings in the two types of sinuous channels. This work demonstrates the significant influence exerted by additional forcing induced by topographic changes on the modification of flow structure, sediment transport, sedimentary architecture, and morphology within submarine channel systems.</p>