Dispersion Coefficients of Contaminant Transport Model for River Mixing Analysis

The pollutant transport modeling in natural rivers is complex due to the non-uniformities of the channel and irregularities of the river bed, channel meandering, and velocity deviations. For the two dimensional pollutant transport modeling, the research for the dispersion coefficients used in the advection-dispersion equation is necessary for the accurate representation of pollutant movement in natural rivers. Former researches found the dispersion coefficients by using tracer tests, and by using the obtained concentration curves, routing procedures such as the 2D STRP (2D stream-tube routing procedure) was used for calculation. Recently the two-dimensional dispersion coefficient in rivers could be obtained by using the ADCP data of open channel flow using the equation developed by Fischer et al. (1979) which uses the fluctuation of two-dimensional flow data. Therefore, in this research the 2D STRP dispersion calculated results were compared with the ADCP velocity based dispersion calculated results. The experiments were conducted in the River Experiment Center in Andong, Korea. Tracer tests and ADCP measurements were conducted to calculate the dispersion coefficients in the channel. The calculated dispersion coefficients were utilized in a 2D advection-dispersion model. The compared results showed that ADCP velocity-based coefficient is a fractional value of the concentration-based result, and proved the applicability of the ADCP induced dispersion coefficients as an effective method for determination of dispersion coefficients in meandering channels without additional tracer tests.