Quantitative Index of Physical and Social Vulnerability to Current and Projected Coastal Storm Surge Flooding in New York City

Abstract:

Sea-level rise throughout the 21^st century will result in increased flood exposure as current flood levels are achieved more frequently and new flood levels result in more widespread inundation. To increase the resiliency of coastal communities and allow populations to respond and recover to these hazards, it is important to develop a place-based understanding of how storm surge exposure, impacts, and community vulnerability will change over time. This work uses a GIS-based methodology to develop and map a quantitative index of physical and social vulnerability for New York City populations within existing and predicted flood zones to assess overall risk at the intersection of exposure and vulnerability. This index may be used to inform decision makers about the heterogeneous landscape of community-level vulnerability in New York City.

Both the physical and socio-economic impacts of flooding events are often unevenly distributed, with socially vulnerable groups most likely to experience a disproportionate share of the detrimental effects. When both physical and socio-economic vulnerability are present in combination, the risk to populations is exacerbated. The combination of social vulnerability, critical infrastructure at risk, and exposure to hazard provides a metric to rank neighborhood risk to flood hazards through a quantitative vulnerability index that characterizes site-specific levels of risk to flood hazard. Results show that a range of mitigation and hazard preparation strategies, and a variety of response and recovery assistance measures are required to address the diversity of local-level flood risks. For some locations the greatest threat is the physical exposure to floodwaters while in other areas social vulnerability compromises the ability of the community to recover from even low exposure flood events. In many locations several elements of vulnerability overlap to create a heightened overall risk to flood events. These areas may require more intensive or specialized planning to protect people and infrastructure from flood impacts.