Hillslope management practices significantly alter the erosion process and its accompanying spatiotemporal dynamics of soil carbon. However, the hydrodynamic mechanisms regulating multiphase carbon loss under different management practices remain unclear. This study investigates how hydrodynamic processes drive the transport of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), soil organic carbon (SOC), and soil inorganic carbon (SIC) during erosion events. Field rainfall simulation experiments were conducted to assess four typical slope management treatments on the Loess Plateau: terrace (TP), grassland (GP), root system (RP), and bare land (CK, control). Key hydraulic parameters (flow velocity, Reynolds number, Froude number, resistance coefficient, shear stress, and stream power) were measured or derived to characterize the hydraulic conditions influencing carbon loss. Results showed that compared with CK, the treatments reduced DOC flux by 38.4-68.7 %, DIC flux by 1.2-47.9 %, SOC flux by 85.8-98.5 %, and SIC flux by 89.3-98.3 %. CK and RP treatments primarily lost carbon through sediment migration (89.7 % and 57.3 %, respectively), while TP and GP treatments primarily lost carbon through runoff migration (50.1 % and 76.2 %, respectively). Moreover, eroded carbon was predominantly lost in the form of inorganic carbon. Hydraulic parameters indirectly influenced carbon loss by modifying runoff rate and sediment discharge rates. Under bare slope conditions, both runoff-and sediment-associated carbon fluxes were primarily controlled by sediment transport dynamics. Following surface interventions, runoff-associated carbon flux became increasingly governed by runoff redistribution, while sediment-associated carbon flux remained closely coupled with sediment discharge. These findings offer important insights into the multiphase carbon transport mechanisms associated with soil erosion under different slope management practices.