Indicators for contaminant transport in a three-layer wetland with wind.

• The effect of wind has been taken into account in analyzing the dispersivity. • The method of asymptotic analysis is adopted to study the dispersivity. • The effect of ecological degradation has been taken into account. • The critical length and duration of the influenced region has been illustrated. The effect of global climate change is increasing and it can influence agriculture in many ways, especially in that it makes great threaten on agricultural water resources. Since agricultural water supply is a key issue for agricultural production, indicators for contaminant transport in wetlands should be considered in order to solve agricultural water pollution and promote water protection. In this paper, we analyze the environmental dispersion in a typical three-layer wetland flows with the effect of wind taken into account. The analytical solution for velocity distribution is rigorously derived and the dependence of characteristic parameters on averaged dimensionless velocity is recorded. The asymptotic analysis theory of Gill is employed to measure dispersivity for natural wetland flows with a commonly high Peclet number. Both velocity and environmental dispersion are significantly influenced by wind, in terms of its direction and the magnitude of force. The effects of hydraulics and ecological degradation are considered to obtain the analytical solution for the mean concentration and maximal critical length of the region influenced by the process of contaminant transport. [ABSTRACT FROM AUTHOR]