Two-scale analysis for environmental dispersion in a two-layer wetland

• Two-scale perturbation analysis is applied for the two-layer wetland flows.
• The theoretical framework is on the basis of phase average and Taylor dispersion concept.
• The analytical expression for the environmental dispersivity is simplified.

Studies on environmental dispersion are essential for applications as water management. The two-scale perturbation analysis is applied in this paper to deduce the environmental dispersion model for the typical case of contaminant transport in two-layer wetland flows. The analysis follows the established theoretical framework on the basis of phase average and the concept of Taylor dispersion. By the obtained flow velocity distribution for the two-layer flow, the analytical expression for the environmental dispersivity is deduced and shown to be consistent with previous results by the concentration moment method, while with much simplifications on the expression for ignoring the less concerned time-dependent stage of the dispersivity.