Building resilience to storm surges and sea level rise

Building resilience to storm surges and sea level rise:
A comparative study of coastal zones in New York City and Boston

Lead-PI:  Malgosia Madajewicz, Columbia University Center for Climate Systems Research

Co-PI: Alan Blumberg, Stevens Institute of Technology

Co-Investigators:  Philip Orton, Stevens; Mark Becker, Columbia CIESIN

Statement of the problem
Large proportions of the United States’ population, infrastructure, and economic wealth are vulnerable to flooding caused by storm surges along the coastal north-eastern urban corridor (NEUC)1 (Frumhoff et al. 2007). In 2003, 53% of the population of the United States lived in coastal counties, with 34% of that 153 million residing along the northeastern Atlantic coast, which has 4 out of 10 of the nation’s largest cities (NOAA 2004). The population pressure along the coastal NEUC has eroded coastal ecosystems and their role as protective buffers against storm surges, compounding the vulnerability of society and nature (Frumhoff et al. 2007).

Storm surges are among the deadliest and most costly natural disasters (Parker 2010). In New York City (NYC) and Boston, billions of dollars of urban infrastructure lie less than 4 meters above mean sea level. Hurricane Irene was only a tropical storm when it made landfall in NYC, and it only caused a modest storm surge of 1.4 meters. However, this storm caused estimated damages totaling at least $55 million in NYC (The Associated Press 2011), flooded waterfront highways, and came close to damaging major electrical and transportation infrastructure. Hurricane Irene was preceded by a mandatory evacuation order affecting 370,000 people in NYC (Bloomberg 2011). Three hurricanes in or near NYC in 1788, 1821 and 1893 had storm surges of 3 – 4 meters and flooded about half of Manhattan below 34th Street and large swaths of East Harlem, Queens, Brooklyn and Staten Island (Scileppi and Donnelly 2007).

Increased damage from coastal flooding related to storm surges is among the most certain impacts of climate change along the coastal NEUC (Frumhoff et al. 2007). Climate change has a two-fold impact on coastal storms. First, storms are likely to bring more intense rainfall (see for example Trenberth et al. 2003; Rosenzweig et al. 2010). Second, sea level rise will raise the height reached by storm surges (e.g. Solomon et al. 2007). Even conservative sea level rise
projections triple the frequency of current 1 in 10 year coastal floods in many areas (Horton et al. 2010; Horton et al. 2008). The increased flooding risk could greatly impact NYC’s and Boston’s coastal communities, critical infrastructure, and major urban transportation routes, as well as compound development pressures from anticipated population growth (Kirshen et al. 2004; Rosenzweig et al. 2011). In NYC, for example, Rosenzweig et al. 2011 estimate that “a direct hit from a major hurricane would cause $100s of billions in damage, with economic losses accounting for roughly two times the insured loss” (94). In metropolitan Boston, sea-level rise of about 20 inches will increase the value of assets exposed to damage by coastal storms from less than $100 billion today to about $500 billion (Climate Action Leadership Committee 2010).

Summary of proposed work

In this project, we will seek to advance the design of effective approaches to adaptation to coastal flooding associated with storm surges, based on research in two cities, NYC and Boston. We will work with decision makers in NYC and Boston to design and evaluate adaptation blueprints for different types of neighborhoods. We will inform the design with a multi-dimensional analysis of vulnerability to coastal flooding.  We will produce probabilistic predictions of coastal flooding for the 2010s, 2050s and 2080s, in the form of spatial maps of inundation probability per year. We will combine the inundation maps with dynamic maps of a vulnerability index that combines information about several dimensions of vulnerability as represented by land use, characteristics of infrastructure, and socioeconomic data. We will work with decision makers to use the vulnerability maps to develop blueprints that specify adaptive decision and implementation processes for adaptation in different types of neighborhoods. We will assess the likely impacts on vulnerability and costs of approaches proposed in each blueprint, and we will determine under what conditions each blueprint may be effective in other coastal urban areas.

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