Author(s): Birgitte Von Christierson, Michael Butts, Laura A. Nieuwenhoven, Flemming T. Hansen, Jannick K. Jensen, Jane R. Poulsen
Linked Author(s): Birgitte Von Christierson
Keywords: River and wetland restoration, integrated modelling, flooding, hydro-period, water quality
Abstract: River channelization and agricultural drains have been widely used across Europe to improve land drainage, increase productive areas and control flooding. However, this has introduced a number of adverse environmental impacts, including the loss of riparian wetlands. It is now widely recognized that riparian wetlands provide beneficial functions to the wider environment through their hydraulic connection to rivers and streams. Through water storage and retention, wetlands support biodiversity, mitigate floods and serve as nutrient buffer zones for the river system. The restoration of rivers and riparian wetlands is increasingly being used to achieve "good ecological status" of water bodies as required by the EU Water Framework Directive (WFD). In Denmark, wetland restoration is used to improve riparian and channel habitats and to reduce the nutrients loads to Danish streams and fjords. While many studies indicate improved water quality, as a result of wetland restoration, the influence of extensive alterations on the hydraulic interaction between flows in streams, their floodplains and subsurface flows, together with the effect on nutrient processes, has received limited attention. In this study, an integrated eco-hydrological modeling tool is presented representing flow, transport and water quality processes in riparian wetlands that can be used to quantify the impacts of both river restoration and the construction of riparian wetlands. This tool is applied to a restored riparian wetland on the Odense River in Denmark. Results show that the flooding behavior from the stream is critical for nitrate removal, accounting for 85-90% of total nitrate removal. Removing drains is also of significance with respect to restoring natural groundwater flow conditions but less significant in terms of nitrate removal in the subsurface for this particular wetland. The results demonstrate the applicability of this modelling tool for evaluating the benefits of wetland restoration and for use in wetland design
Year: 2017