Abstract
A numerical simulation model is suggested for estimating the water quality in tidal urban rivers. The model is composed of two submodels, which calculate unsteady flow and diffusive process of SS and BOD. In the second model, BOD was further divided into dissolved and particulate matter, while SS was divided into organic and inorganic matter. Taking the strong relationship between organic SS and particulate BOD into concideration, water quality was estimated. Some important coefficients in the second model such as self-purification factor and the conversion factor of SS into particulate BOD were determined by field data in a tidal urban river. Introducing these determined parameters into this simulation model, BOD and SS were estimated. Estimated ones well coinsided with the observed ones in the Shinmachi river.
