Designing Wetlands as an Essential Infrastructural Element for Urban Development in the era of Climate Change

The increasing development of urban infrastructure has led to the significant loss of natural wetlands and their ecosystem services. Many novel urban development projects currently attempt to incorporate environmental sustainability, cross-disciplinary collaboration, and community engagement into the intricate challenges we all face in an era of climate change. This paper aims to communicate several key findings on design elements that can be adopted or incorporated in the design of created wetlands as infrastructural elements. Three major design elements—microtopography, hydrologic connectivity, and planting diversity—are presented, and their relations to restoring ecosystem services of urban wetlands, in particular water and habitat quality, are discussed. These design elements can be easily adopted or incorporated in the planning, designing, and construction stages of urban development. The success of urban infrastructure projects may require both better communication among stakeholders and a great deal of community engagement. The Rain Project, a floating wetland project on an urban college campus, demonstrates the role of interdisciplinary collaboration and community engagement as a model for sustainable stormwater management, a critical part of today’s urban development. Further efforts should be made to advance the science of designing urban wetlands and its communication to transform cultural attitudes toward sustainable urban development.

Developing an ecosystem model of a floating wetland for water quality improvement on a stormwater pond

An ecosystem model was developed to assist with designing and implementing a floating wetland (FW) for water quality management of urban stormwater ponds, focusing on nitrogen (N) removal. The model is comprised of three linked submodels: hydrology, plant growth, and nitrogen. The model was calibrated with the data that resulted from a FW constructed and implemented as part of an interdisciplinary pedagogical project on a university campus, titled "The Rain Project", which raised awareness of stormwater issues while investigating the potential application of green infrastructure for sustainable stormwater management. The FW had been deployed during the summer of 2015 (i.e., May through mid-September) on a major stormwater pond located at the center of the Fairfax Campus of George Mason University near Washington, D.C. We used the model to explore the impact of three design elements of FW (i.e., hydraulic residence time (HRT), surface area coverage, and primary productivity) on the function of FW. Model simulations showed enhanced N removal performance as HRT and surface area coverage increased. The relatively low macrophyte productivity observed indicates that, in the case of our pond and FW, N removal was very limited. The model results suggest that even full pond surface coverage would result in meager N removal (∼6%) at a HRT of one week. A FW with higher plant productivity, more representative of that reported in the literature, would require only 10% coverage to achieve similar N removal efficiency (∼7%). Therefore, macrophyte productivity appears to have a greater impact on FW performance on N removal than surface area coverage or pond HRT. The outcome of the study shows that this model, though limited in scope, may be useful in aiding the design of FW to augment the performance of degraded stormwater ponds in an effort to meet local water quality goals.