Using multifunctional GI to address resilience in cities

Stephanie Marie Miller

doi:10.17918/etd-7595

Cities are currently facing numerous challenges and uncertainties - climate change, aging infrastructure, growing urbanization - with many turning towards green infrastructure (GI) as a possible solution. Perhaps the most common application of GI is for stormwater management, though some cities are also hoping to use GI to combat climate change and urban heat islands, recharge groundwater supplies, and restore habitat for native fish and wildlife. Though many municipalities are using GI, few have a comprehensive vision for GI or consider all the possible benefits when planning, siting, and designing new sites. As a result, efforts remain largely uncoordinated and disjointed, with many missed opportunities. This is partly because the exact benefits of GI remain largely unquantified. Without knowing what to expect, cities are hindered in their efforts to integrate GI into broader goals and coordinate across programs. To address this need, this dissertation adopts a mixed method approach to address some of the knowledge gaps surrounding GI's co-benefits. Specifically, statistical modeling, participatory engagement, and complex, multi-agent modeling are used to more clearly define and measure the ES available from various GI sites. For all efforts, New York City was used as a case study, although the methods used here are applicable to all cities. First, this research focused on quantifying the benefit of a single ES, mitigation of environmental disturbances, during Hurricane Sandy. This is a service often attributed to GI, but poorly understood in urban settings. Despite the numerous anecdotes that stated GI had protected people and property from the worst of Sandy, results of this research suggest GI is limited in its ability to provide protection during extreme coastal events. The second part of this research used stakeholder interviews and surveys to quantify the value of all ES from multiple GI types. Results suggest that NYC could get more value from its GI investments through minor changes to program, e.g. including more community gardens and refocusing messaging away from stormwater management, a services New Yorkers do not value. Lastly, this research used an agent model to simulate two different approaches to greening in NYC and measure physical, social, and economic consequences of GI looking specifically at how stormwater capture, public approval, and the economic value of these new investments will change over time. Simulations indicate that NYC is capable of meeting, and even exceeding, the stormwater management potential of its current program by taking a more multifunctional approach to GI and trying to address community needs first, and stormwater second. The results suggest that integrating GI with other initiatives, including improving resilience, should improve the co-benefits available for New Yorkers, including stormwater management services. The approaches taken in this research pilot methodologies for quantifying and calibrating the value of benefits of GI according to local preferences and demonstrates, through two separate modeling efforts, that GI is most useful when addressing multiple concerns as opposed to providing a single service (e.g. mitigation of environmental disturbances or stormwater management). Taken together, the results underscore the idea that GI can provide multiple services to cities, and that these benefits can be maximized through a more comprehensive approach to GI. As cities look to increase their resilience to the many challenges of the 21st century, GI can play a significant role in achieving those goals. However, to do so, cities will need to find a way to coordinate GI efforts across programs to get the most out of their investments. GI is most useful as a tool for building resilience when it is multifunctional and integrated into all aspects of urban planning.

Using multifunctional GI to address resilience in cities

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Using multifunctional GI to address resilience in cities

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