Modeling green infrastructure as a flood mitigation strategy in an urban coastal area

Urban areas can be seriously disrupted by flooding after heavy rain events. Therefore, several strategies based on grey infrastructure have been implemented over the years to mitigate the impact of significant rainfalls and make urban areas more resilient against flash floods. Green Infrastructure (GI) is an environmentally appropriate alternative which can reduce the amount of stormwater delivered to a drainage system within an urban area while mitigating the contamination carried with it. To date, however, relatively little attention has been paid to public acceptance and to the challenge GI may face in the presence of shallow aquifers. This paper presents a framework for assessing the social and technical feasibility of GI in a coastal urban area with a shallow aquifer. The method consists of the assessment of potential scenarios upon the assessment of government acceptance coupled with a stormwater management model. The urban laboratory for this study is the city of Hoboken (NJ) which is located near the estuary of the Hudson River. It was selected due to the availability of data, its vulnerability to flooding, and the presence of a shallow aquifer. Results from interviews indicate positive feedback for the implementation of GI, but specific GI techniques could not be identified. So, based on generally accepted GI measures, right-of-way, resiliency parks, and green roofs were considered and implemented into a stormwater management model. The model was used to simulate the performance of various GI options to minimize stormwater runoff. Simulation results show that all the alternatives considered are effective in reducing runoff volumes for rainfall events of less than a 1-year recurrence interval. However, they do not mitigate the negative impact of heavier rain events due to limited storage as a consequence of the size of the site and the shallow aquifer within the coastal urban area.