A grid-based pollutant load runoff model was developed and applied to the basin of Turumigawa river. This model based on physical based hydrological cycle analysis model, and as a result reproducibility of calculations about water quantity is reasonably good. In this model, pollutant load source account for point source and non-point source. Calculated river water quality, using this model, have been verified for sunny and rainy condition. These calculations are consistent with the observations. This model is useful for basin water management because of it is used to assess water quality influence of land use change and effect of tactics.
