Environmental dispersion in a three-layer wetland flow with free-surface

• To give a velocity profile of the effective flow through the three-layer wetland.
• To present an environmental dispersion model by the extension of Taylor’s classical analysis.
• To determine the environmental dispersivity by concentration moments method.
• To analyze the effects of characteristic parameters on the velocity profile and environmental dispersivity.
• To illustrate the evolution of contaminant cloud in terms of critical length and duration of an influenced region.

To further address the characteristic of contaminant transport in wetlands of a multi-layer structure, environmental dispersion of a pulsed contaminant emission into a steady flow is analytically explored in this paper for the typical case of a respectively vegetated or packed three-layer wetland dominated with free-water-surface-effect. The hierarchical structure for the critical length and duration of the contaminant cloud is illustrated for the dispersion of typical contaminant constituents.