Soil loss and its transport processes were coupled with an existing distributed hydrological model
to assess the effects of land use change on stream flow and suspended sediment load in the Chao
Phraya River basin, Thailand. The simulation period spanned from 2001 to 2010. The results
indicate that the Nash-Sutcliffe efficiency of upper sub-basins fluctuated in the range 0.51- 0.72,
indicating the applicability of the model for longterm simulation at the monthly scale. Land use
change during 200l-2010 caused a 1.6% increase in suspended sediment load based on the present
trend. The changes were particularly pronounced in the Wang River basin, where the delivery ratio
was highest. Moreover, the urbanization and conversion of farm land from paddy fields exerted
negative effects on sediment runoff in Chao Phraya River basin. The proposed model has the
ability to quantitatively evaluate the heterogeneity of sediment runoff in the basin, demonstrating
the benefits and trade-offs of each land use change class. The results of this study can support basin
and local land development policy to control sediment losses during development.
