DISTRIBUTED MODEL OF HYDROLOGICAL AND SEDIMENT TRANSPORT PROCESS IN MEKONG RIVER BASIN

Soil erosion and sediment transport have been modeled at several spatial and temporal scales, yet few models have been reported for large river basins (e.g., drainage areas > 100,000 km2). In this study, we propose a process-based distributed model for assessment of sediment transport at a large basin scale. A distributed hydrological model was coupled with a process-based distributed sediment transport model describing soil erosion and sedimentary processes at hillslope units and channels. The model was tested in Mekong River Basin (795,000 km2). The simulation over 10 years showed good agreement with the observed suspended sediment load in the basin. The average Nash–Sutcliffe efficiency (NSE) and average correlation coefficient (r) between the simulated and observed suspended sediment loads were 0.60 and 0.78 respectively. Sensitivity analysis indicated that the suspended sediment load is sensitive to soil detachability over land (Kf) in the Mekong River Basin. Overall, the results suggest that the present model can be used to understand and simulate erosion and sediment transport in large river basins such as Mekong River Basin.