Abstract
In order to prevent water pollution of rivers in general, it is important to control water quality and pollutant loads of small and medium rivers, including tributaries, which contribute essential portion of pollutant loads. For this purpose, runoff characteristics of pollutants from small and medium rivers were studied, and runoff and decay coefficients of pollutants were examined in relation to transport, sedimentation and scouring of pollutants.
In the first half of the paper, the major contoling factors of the runoff coefficient and their constituent elements were discussed, and the methods to describe the relationship between pollutant loads and quality of receiving water were presented putting particular emphasis on non-point sources of pollutants.
In the latter half, the results of case study with several small and medium rivers were shown to analyze the mass balances of pollutants and the relationship between pollutant runoff characteristics and time-varying properties of rivers such as flow, water quality and the amounts of pollutant load. In addition, the variation of runoff and decay coefficients with flow distance were also analyzed.
