show profiles of pollutant runoff by simulating the change of pollutant runoff with the variance of characteristics of river basins (i.e. population, urban area, rate of sewerage, etc.). The model, hereinafter referred to “MACRO MODEL”, consists of three main sections. The first one shows pollutant runoff from point sources, taking the sedimentation of pollutants in sewers into consideration. The second one and the third one show pollutant runoff from nonpoint sources in urban area and rural area, taking land use into consideration. As it was proved that MACRO MODEL could simulate pollutant runoff correctly enough to forecast runoff profiles of pollutants, it came to be possible to estimate the effect of characteristics of river basin to pollutant runoff. As a result, some available knowledge, which were concerned with the environmental management of water, were obtained by using MACRO MODEL.