Abstract:In order to test the flow exchange behavior in the channel-floodplain system,a particle tracking code based on Lagrangian particle tracking method (LPTM) was used to further analysis flow interaction between the main channel and floodplains in Truckee River at McCarran,Nevada.The particle trajectory,the residence time distribution (RTD) and the spatial interaction frequencies were examined under two different frequency flood events.Results showed that the lateral flow traveling distance is enhanced by higher discharge.The RTD showed that the higher discharge leads to a shorter mean residence time,and the ratio of particles amount that involved in exchanges between main channel and floodplain is larger in a stronger overbank flow event.The spatial interaction frequencies revealed that the discharge has significant impacts on the longitudinal traveling distance per a single interaction of the released particles.It indicated that the overall exchange is stronger at a higher flow and the local exchange is relatively weaker than in a lower flood event.The LPTM approach can provide a reference for the river modification and restoration.