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Calculation of Dispersion Coefficients by Routing Procedure in Two-Dimensional River Mixing

Author(s): Kyong Oh Baek; Il Won Seo

Linked Author(s): Il Won Seo

Keywords: Routing procedure; Dispersion; River mixing; Meandering; Tracer dat

Abstract: Methods of calculating the dispersion coefficient can be roughly classified into two categories; an observation method, and a prediction method. The former evaluates the dispersion coefficient from the concentration data which can be obtain by a tracer test. The latter estimates the dispersion coefficient based on the hydraulic parameters when there is no concentration data. In observation methods, what are used commonly is moment-based methods. An alternative methodology for observed dispersion coefficient is a routing procedure which is originally used to predict flood waves in hydrologic field. In this study, a routing equation which can be applied under a transient concentration situation with taking into account river irregularities in two-dimensional river mixing was developed. The proposed routing procedure was applied to meandering rivers where field tracer tests were conducted by Seo et al. (2006). The observed dispersion coefficients by the routing procedure showed longitudinal variations along river, that is, a minimum value was seen in the straight region and a maximum value in the bend with greatest curvature. This was due to the flow dynamics induced by meandering effects. The dispersion coefficients averaged over the reach, on the whole, were in good agreement with those by other methods. From these facts it was concluded that the dispersion coefficients could be reasonably calculated by means of the new routing procedure.


Year: 2007

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