Discharge of wastewater, sewerage and runoff from coastal cities remains the dominant sources of coastal zone pollution. The impervious nature of modern cities is only exacerbating this problem by increasing runoff from city surfaces, triggering combined sewer overflow events in cities with single-pipe wastewater conveyance systems and intensifying urban flooding. Many coastal cities, including US cities like Seattle, New York and San Francisco, are turning to urban green infrastructure (GI) to mitigate the city's role in coastal zone pollution. Urban GI, such as green roofs, green streets, advanced street-tree pits, rainwater gardens and bio-swales, introduce vegetation and perviousness back into city landscapes, thereby reducing the volume and pollutant loading of urban runoff. Urban GI, however, also has co-benefits that are equally important to coastal city sustainability. For example, increasing vegetation and perviousness within city boundaries can help cool urban environments, trap harmful air-borne particulates, increase biodiversity and promote public health and well-being. Despite the significance of these co-benefits, most current urban GI programs still focus on achieving volume reduction of storm water through passive detention and retention of rainfall or runoff. Holistic approaches to GI design that consider multiple sustainability goals are rare, and real time monitoring and active control systems that help ensure individual or networked GI meet performance goals over desired time-scales are lacking. Furthermore, how city inhabitants view, interact with, and value GI is little studied or accounted for in current urban GI programs. This project will develop and test a new framework for the next generation of urban GI that exploits the multi-functionality of GI for coastal city sustainability, builds a platform for real-time monitoring and control of urban GI networks, and takes account of the role of humans in GI stewardship and long-term functionality. The project will use the Bronx River Sewershed in New York City, where a $20 million investment in GI is planed over the next 5-years, as its living test bed. GI has its roots in several disciplines, and the project brings together expertise from these disciplines, including civil and environmental engineering, environmental science, and plant science/ horticulture. In addition, the project integrates expertise from other disciplines needed to elevate GI performance to the next level, including urban planning and design, climate science, data science, environmental microbiology, environmental law and policy, inter-agency coordination, community outreach and citizen science.
The specific outcomes of the project will include: (i) new, scientific data on the holistic, environmental performance of different GI interventions in an urban, coastal environment; (ii) new models for the system level performance of networks of GI interventions; (iii) methodologies for projecting GI performance under a changing climate; (iv) a platform for remote monitoring and control of GI; (v) proposals for law and policy changes to enable US coastal cities to introduce GI at scales necessary to meet sustainability goals, and (vi) new understanding of human-GI interactions and their role in the long-term performance and maintenance of urban GI. Engagement with schools in the Bronx River Sewershed and engagement of citizens in the GI performance monitoring are both important components of the project work. The interdisciplinary project team integrates academic expertise with expertise in industry, government and non-profit organizations.
A leader in the field of water resources and urban sustainability, Culligan has worked extensively with The Earth Institute's Urban Design Lab at Columbia University to explore novel, interdisciplinary solutions to the modern day challenges of urbanization, with a particular emphasis on the City of New York. Culligan is the director of a joint interdisciplinary Ph.D. program between Columbia Engineering and the Graduate School of Architecture Planning and Preservation that focuses on designs for future cities, including digital city scenarios.