Rainfall]runoff, sediment production and flow]out in mountain watershed are simulated. Runoff is calculated from rainfall as kinematic wave. Sediment production and flow]out are calculated as an one dimensional model. This simulation model is a modified version of SERMOW for Sediment Runoff from a Mountain Watershed. It is named SERMOW]II. This model is applied to the observed rainfall, runoff and sediment measurement data for the Ashiarai]dani basin. The model considers various types of sediment transport; from debris flow to bed load, although landslides on slopes are not considered. The model can explain the data well after adjusting the parameters. The influence of grain size distribution of the supplied sediment to flow]out sediment was examined with the model.

Key wordsFrainfall]runoff, sediment routing, mountain watershed, modeling, SERMOW]II