Mapping Flood Vulnerability in East Harlem

By Eddy Almonte, ANHD Morgan Stanley Fellow 2018/19

Affordable housing owned and operated by community development corporations (CDCs) has long been a source of critically-needed housing for low-income families in New York City. According to a recent study, Superstorm Sandy affected 248 buildings, or 24,000 units, of this stock of subsidized housing. How can CDCs better prepare for another Sandy-like storm while also preserving the affordability and sustainability of their developments?

Figure 1

Before joining the Ascendant team as their Morgan Stanley ANHD Community Development fellow, I was researching case studies in emergency management and funding in New Orleans and Flint as an urban planning graduate student. This research led to a curiosity on how disasters affect the various players in affordable housing development and what measures are needed to enhance social and physical resiliency.

In late 2018, Zef Egan, a former sustainability consultant for Hope Community Inc. (HCI) in East Harlem, approached the Urban Systems Lab at the New School to study the effects of inland basement flooding on HCI’s developments in East Harlem. The project evolved into a partnership between HCI and Ascendant to study and understand the comprehensive effect of flooding and climate change on our apartment buildings and residents. Veronica Olivotto, a Ph.D. candidate at the New School’s Milano School of Policy, Management, and the Environment, joined the project to provide additional research and mapping capacity. The research partnership would allow Veronica to think about possible dissertation topics in environmental justice and citizen science.figure 2
In order to understand the comprehensive effect of flooding and emergency preparedness, Veronica and I created a vulnerability index

and statistically clustered each property lot in Community Board 11 by that index. Property lots located within the 2017 East Harlem rezoning, census tracts of median household income of less than

NMC Hotspot 2

Figure 2

$30,000, buildings with expiring rent subsidies, and three different flood zone projections were each assigned a unique score (figure 1). A cluster analysis allowed us to identify “hotspots” within in East Harlem where all four variables were present (figure 2). These hotspots were then overlaid with HCI’s and Ascendant’s current and future housing developments to identify exposure to this vulnerability.

Five out of 28 properties owned by Ascendant are between the 90-99% confidence level of the hotspot analysis, meaning that there is between 90 and 99% confidence that these lots are more affected by changes in the rezoning, higher numbers of low-income residents, rent subsidy expiration, and current and future floodplains. 19 out of 79 properties owned by HCI fell into this same category (figure 3).

For both Ascendant and HCI, this means that building-specific emergency preparedness plans and streamlined resident engagement programs should be prioritized for developments in the 90-99% confidence level. Capital improvement projects can prioritize resiliency measures like renewable energy and sustainable building material. Most importantly, this project can be scaled up to the Northern

VulnerabilityClusterIndex 2

Figure 3

Manhattan Collaborative network, which includes 157 buildings and 2,754 households. Joint financing for solar energy through the collaborative can pave the way for Community Solar and micro-grid potential and expand these efforts to more affordable housing developments.

This study attempts to focus on the potential effects that CDCs can have on developing sustainable affordable housing in the private market while maintaining social infrastructure during and after disasters. The entire study and additional maps can be found on the scholarly open access platform Authorea.

After my ANHD fellowship ends in June, I will be continuing as a Development and Sustainability Intern at Ascendant, where I will help with future development projects and implementation of resiliency measures. We hope to share this study with as many community leaders as possible as I continue my work in East Harlem and beyond.




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