Abstract
For the water quality management at receiving waters, the reduction of inflow of pollutant materials from watershed is very important. In this study, in order to clear the pollutant runoff from Honmyo river basin in Nagasaki, Japan, during the wet weather condition, the field observations and the development and application of numerical simulation model were carried out. The observed results show that the concentration of suspended solids (SS) varies with the temporal change of water discharge. At the beginning term of their runoff, first flush can be observed. In the numerical modeling, runoff rate of SS was treaded as the function of the discharge at watershed and the cumulative runoff of SS. From the comparison of computed results and observed ones, it is considered that the developed model can estimate the temporal variation of water discharge and concentration of SS with acceptable errors.
