Influence of vegetation on the hydraulic behaviour of a reconstructed wetland

The ecohydrological approach can be applied to reconstructed wetlands where an appropriate vegetation design is needed in order to optimise hydraulic behaviour, water quality improvement and biodiversity increase. The purpose of this study is to examine the hydraulic effects of different development stages of vegetation in a demonstrative reconstructed wetland in Italy characterised by a central canal and two vegetated lateral shallow zones. Tracer tests were carried out in different vegetation conditions. The residence time distributions were analysed using several parameters. As expected, the results show that with more developed vegetation the hydraulic dead zones increase. On the other hand, a moderate increase of vegetation density doesn't hinder the flow, but rather increases dispersion number. A proper design has to avoid hydraulic short circuiting and provide a good distribution of the flow especially in the vegetated zones.