Mapping the Vulnerability to Flooding of Community-Development Corporations (CDCs) Affordable Housing Properties in Central and East Harlem, New York City
New York City’s affordable housing stock is vulnerable to coastal flooding under current and projected climate scenarios. Flood vulnerability in this study, was intended as a factor of the exposure of affordable housing units to current and future floodplains as well as topographical elevation. Variables of socio-economic vulnerability included median household income by census tract, expiring affordability of rent-subsidized housing, and East Harlem’s most recent rezoning . The affordable housing in question is owned by two community-development corporations (CDCs) of the Northern Manhattan Collaborative (NMC), Hope and Ascendant based in East Harlem. Using GIS software and publicly available data from NYC Open Data and Mapluto, large scale mapping was conducted at the Borough-Block-Lot (BBL) scale to understand the exposure to coastal flooding of 101 properties owned by Hope and Ascendant, as well as a Hotspot Analysis of all the remaining units included in the NMC (48 more properties). Results show that Hope properties may flood more than Ascendants', under both current and future floodplain projections. A contributing factor is topographical elevation, where Hope Properties are at lower median elevation (13.2 feet) than Ascendants' (29 feet) and also lower than the median elevation of both Central (22 feet) and East Harlem (15 feet). Results from the hotspot analysis shows that 20 of Hope Properties fall within Hot clusters of socioeconomic vulnerability, as well as 5 of Ascendant Properties. Overall the NMC Properties show a higher socioeconomic vulnerability than all the properties in East Harlem. This result is important considering that New York City’s stock of affordable housing hosts some of the most vulnerable populations in the city, with less ability to move elsewhere before or after a flooding event.