Solute Transport in Open Channel Networks under an Unsteady Flow Regime

Mustafa M. Aral and Yi Zhang

Multimedia Environmental Simulations Laboratory

School of Civil and Environmental Engineering

Georgia Institute of Technology

Atlanta, Georgia 30332

Abstract

In this study we formulate and test a robust algorithm to analyze solute transport in open channel networks with transient storage effects under an unsteady flow regime. In the proposed approach, the analysis of solute transport problems in open channel networks is simplified through the integration of junction equations into the numerical model and solving them explicitly. Furthermore, when coupled with transient hydrodynamic open channel network model for flow simulation, the proposed model may be utilized in the solution of solute transport problems under unsteady flow regimes. In the proposed model, the governing equations are written in conservative form, and fractional-step algorithm, which is based on a relaxation scheme and central finite difference scheme, is utilized for the solution of governing equations. The proposed algorithm is robust and accurate even in dominant advection cases. Three examples including pure advection with discontinuities, a field application, and solute transport in an open channel network in an unsteady flow regime is included in this report to demonstrate the performance of the proposed algorithm.

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