Certain populations are more vulnerable to the social and economic impacts that come from natural or human-caused disasters. Due to their socioeconomic conditions, some groups may be more vulnerable to a transmittable disease, such as COVID-19, or to environmental hazards, such as stormwater flash flood events. There are often significant overlaps in the demographic characteristics of populations experiencing different vulnerabilities, resulting in compounding and cascading effects, and very distinct risk profiles.

New York City neighborhoods with the highest rates of positive COVID-19 cases and deaths face the highest rates of rent burden and household overcrowding. Health equity accounts for the disparate effects of those who are more likely to suffer from the secondary impacts of isolation, lost income, homelessness, and other consequences that result from a health crisis or a natural disaster, even if they don’t become sick themselves.

The city’s 2.5 million service workers were at the center of the pandemic as it ravaged New York. Many found themselves unemployed in one of the most expensive cities in the country. The places where service workers live are also highly correlated with metrics measuring social vulnerability. Socioeconomic factors also have great influence over other health outcomes, not just COVID-19.

Research by University of Wisconsin Population Health Institute and Robert Wood Johnson Foundation indicates that the bulk of population health outcomes are determined by social and economic factors, such as income, education, or family and social support as well as environmental factors such as walkability or access to services.

Housing conditions are one of the major factors that determine health outcomes. The cost of housing in particular makes it difficult for those with low and moderate incomes to afford health care, nourishing food, and the other resources essential to good health. As a result, individuals might stay in substandard conditions due to financial constraints and be exposed to risky conditions, such as high levels of mold and lead, poorly functioning heating systems, or greater flood risks. Others are forced to live in overcrowded conditions, making it impossible to implement social distancing measures.

In the tri-state region and beyond, people live in places they can afford. The ongoing trends of regional and national housing scarcity have forced many New Yorkers to resort to living in unlicensed basement apartments. In September 2021, more than a dozen people died in those apartments when the remnants of Hurricane Ida dumped a record amount of rain in the city, causing severe flash flooding. Many others lost their assets and possessions. Most of these victims were low-income immigrants.

Deliberately incorporating health into how we plan our physical environment and infrastructure can deliver better health outcomes, while expanding our economy and protecting our environment. As the aftermath of Hurricane Ida and the COVID-19 pandemic have demonstrated, the growing intersections between climate adaptation, housing insecurity, and health outcomes demand a new approach for infrastructure planning, one that recognizes the physical features in both the built and natural environmental systems that shape our communities and economy.

The study area is physically divided north and south by Queens Boulevard and the Long Island Expressway. Along and at the intersection of these two thoroughfares, neighborhoods are served by large retail motor vehicle-oriented facilities such as Queens Center, Rego Center Mall, and Rego Park Plaza. In contrast, neighborhoods in the northern part of the study area are served by pedestrian-friendly commercial corridors along Northern Boulevard, 37th Avenue, and Roosevelt Avenue.

While the study area is home to some large scale residential developments such as LeFrak City and Rego Park, its landscape is largely dominated by semi-detached one-and two-family residences. There are approximately 44,000 of these low-density residential buildings in the study area, many with basement conversions. Approximately 31,000 of these buildings have below-grade basements and another 9,600 have above-grade basements. Property owners frequently convert these spaces into unlicensed apartments. By one estimate, 4,100 unlicensed units exist in Queens Community District 3 alone.

In order to meaningfully reduce future flood loss, the planning and implementation of infrastructure requires urgent innovation and new ambitious milestones. A new framework should expand the scope of the existing Green Infrastructure Program and extend cloudburst pilot projects at a citywide scale. Cloudburst management uses a combination of methods that absorb, store, and transfer stormwater to minimize flooding from quick, heavy precipitation events.

NYC Department of Environmental Protection (DEP) is currently conducting cloudburst feasibility studies that will consider physical vulnerability and below ground conditions, as well as social and economic factors. Given the social and physical characteristics of communities in central Queens, districts here should be prioritized for the future implementation of cloudburst management methods.

We found that in order to fully eliminate flood accumulations of 12 inches or more — the type of flooding associated with property damage and loss — the study area would need an increase in green infrastructure management capacity of approximately 40 times over the current baseline. This could be achieved — at least in part — by implementing cloudburst methods that absorb, store, and transfer stormwater to minimize flooding from extreme events.

Extreme Precipitation and Flood Loss

The Federal Emergency Management Agency (FEMA) estimates that, as a result of Ida’s flooding, the initial damages to New York City properties was $38 million — a preliminary figure that rises far higher if damage to citywide infrastructure and public health are taken into account.

To demonstrate the current gap between stormwater management needs and the scale of adaptive infrastructure required to avoid flood loss, we estimated the difference between the amount of water (in gallons) generated under an extreme precipitation event and the combined design capacity of existing gray and green infrastructure serving central Queens. We conducted the analysis based on the volume of stormwater within the drainage study area assuming an extreme precipitation event of 3.5 inches per hour.

Under an extreme precipitation event of 3.5 inches per hour, the drainage areas within the study area would generate an average of 322 million gallons of stormwater runoff. The largest share of accumulated stormwater runoff within the study area would come from drainage areas BB 005 and BB 006 (BB corresponds to Bowery Bay Treatment Plant), totaling more than 280 million gallons representing 90% of the total volume generated.

From the estimated total average of 322 million gallons, about 220 million would accumulate in areas as deep contiguous flooding (12 inches or more). This type of flooding poses a significant threat to public safety and property. The remaining 100 million gallons would accumulate in areas experiencing nuisance flooding ranging between depths of four and 12 inches. As the name implies, nuisance flooding represents a low level of inundation that poses a less significant threat to public safety or property.

Under a 3.5 inches-per-hour precipitation event, and according to DEP models, approximately 11,000 small residential buildings with basements would be affected within the study area. Most of these basements - over 8,000 - are below grade. In addition to residential property damage and loss of life, an extreme precipitation event of this magnitude would affect more than 10 subway station entrances, as well as portions of the forthcoming Interborough Express alignment, a Brooklyn-Queens rail connection first conceived and promoted by RPA.

New Milestones and Program Expansion

For this report, we estimated that the current management design capacity of green infrastructure within the drainage area is approximately 5.2 million gallons, equivalent to 2.4% of the total amount of flooding associated with damage and loss. In other words, the design capacity of current green infrastructure would need to expand 40 times over in order to completely manage the volume of stormwater associated with flood loss risk in the area.

It is well documented that stormwater management from green infrastructure can reduce flood losses when applied at a watershed or district-wide level as a co-benefit to the primary objective of water quality protection. New York City’s Green Infrastructure Program was conceived to improve water quality and informed by the benefits of avoiding energy and maintenance costs, but its current scope and milestones do not consider flood loss. Incorporating flood risk reduction into an updated assessment framework would have significant repercussions on how city agencies prioritize, fund, and implement green infrastructure, including cloudburst management.

Even within the current scope of the program, green infrastructure installed throughout the city only manages less than a third of the volume established as a benchmark in 2010 when the program was conceived. When the program was launched, it set a goal of managing 1.7 billion gallons a year (BGY) by 2030 (revised to 1.67 by the consent order in 2015). The latest annual report indicates the city anticipated that it would reach 507 MGY by the end of 2021, a time at which the program was past half its implementation timeline.

The city must ramp up the pace of the program significantly and reevaluate the original goals and milestones. To inform new milestones and updated programs, the co-benefits of green infrastructure, including flood loss avoidance, reduced property damage, and diminished exposure to health risks should be factored in a new citywide cost-benefit analysis. This type of analysis should inform major capital investments — for instance, the potential consolidation of Water Treatment Plants at Rikers Island.

The Administration of Mayor Eric Adams should also leverage state and federal sources that could help fund these types of investments. On November 15, 2021 President Biden signed the $1.2 trillion Infrastructure Investment and Jobs Act (IIAJ). This Act allocates unprecedented federal funding to resiliency work nationwide. These funds will help advance numerous adaptation needs in New York City, including the implementation of neighborhood cloudburst management projects and neighborhood planning grants to seed resiliency work. The city can also expand these programs by providing more site-specific tiered incentives and regulations that maximize stormwater management capacity on private properties.

Increasing stormwater management capacity will also depend on a more efficient capital project design and implementation process and greater inter-agency collaboration.

From a physical perspective, the right-of-way (ROW) of city streets presents the greatest opportunity for the expansion of green infrastructure and cloudburst methods. Currently, about 80% of green infrastructure water management capacity in the study area depends on assets located on the right-of-way; the remaining 20% depends on assets located on private properties.

ROW green infrastructure in central Queens — including green streets, infiltration basins, and bioswales — occupy a combined area that amounts to approximately 3 acres. While the right-of-way is a contentious space where multiple uses are in constant competition, central Queens has about 718 acres of sidewalks and 1,600 acres of roadbed. From rain gardens to bioswales, there is no reason why green infrastructure could not be present on every city street that could support it. Assuming that green infrastructure is installed to cover 120 acres of sidewalks and roadbed, representing about 5% of the total right-of-way space within the study area, stormwater management capacity could be increased to handle future storms like Ida.

Even with current street geometries and configurations, there are opportunities to include effective design interventions and rethink the materials we use for our streets. The performance of stormwater management can be increased by designing networks of interconnected bioswales, trench drains, permeable pavers, and rain gardens. Such systems have the potential to manage greater volumes of stormwater within smaller footprints, and thus limit conflicts between green infrastructure and other ROW uses.

NYC DEP already has advanced cloudburst pilot projects, including testing the implementation of cloudburst management at the NYC Housing Authority’s (NYCHA) South Jamaica Houses. According to the DEP, cloudburst management involves a combination of methods that absorb, store, and transfer stormwater to minimize flooding from cloudburst events. In addition to green infrastructure, these strategies may include underground tanks, blue roofs, and monitoring systems to control the release of detention areas. By reducing strain on the sewer system in central Queens a cloudburst management program could significantly improve public safety, while reducing potential damage to property and infrastructure.

Expanding green infrastructure and implementing cloudburst management methods in central Queens will significantly reduce flood loss experienced by basement tenants and owners. Even with these kinds of investments, basement apartments, which fall under the category of accessory dwelling units, should be made safer whenever possible.

Legal Framework and Assistance Programs

Greater housing choice can create more variety in unit prices and living arrangements, meeting a wider range of needs for renters and homeowners. There is also a growing interest in ADUs spurred by the low volumes of housing construction in the region and a greater awareness about unlicensed basement apartments and converted units in the outer boroughs of New York City.

State legalization and regulation of ADUS would enable the full development of supporting programs aimed at bringing existing units to code while also providing tenant protections wherever possible.

Better Information to improve decisionmaking

In order to scope an amnesty and technical assistance program for ADUs, city agencies must first have a better sense of the number, location, and average rents of basement apartments. However, in part due to the current legal status of ADUs in New York, there is limited information about how many units there are and where they are distributed. Existing data sources and efforts used to inform the 2020 Decennial Census could be leveraged to fill this important knowledge gap.

Similarly, existing stormwater flood risk maps should be improved and updated to model ​“extreme scenarios” that assume site-specific precipitation intensities of at least five inches per hour. More accurate and complete information on basement apartments and flood maps, should then be used to implement site-specific tiered alert systems and other emergency preparedness protocols announced in the wake of Ida.

As laid out in the recently released Rainfall Ready NYC Action Plan, there are several emergency preparedness protocols for sanitation and transportation operations that can be put in place. Whenever the forecast calls for rainfall rates at one inch per hour or more, the Department of Emergency Management (DEM) will put in motion a plan that triggers operational agencies to prepare city infrastructure for the incoming storm. In addition, the plan describes the roles that everyday New Yorkers can follow. Residents should consult the city’s flood maps, have the appropriate flood insurance, and set an emergency plan for their household.

While the design and construction of large infrastructure projects to manage our changing climate will take time to complete, these shared actions can be taken in the short-term to ensure public safety.

The majority of deaths and residential property damage that resulted from Ida’s flooding were concentrated in central Queens. The weather station at LaGuardia Airport reported almost seven inches of rainfall that night, accumulated between 9:00pm-4:00am. The combination of extreme precipitation, high concentration of unlicensed apartments, and the underlying socioeconomic factors resulted in the high degree of loss.

Amid growing housing insecurity worsened by climate change and the pandemic, RPA and Make the Road New York (MRNY) highlighted the lived experiences of residents and the benefits of legalizing and supporting ADUs, including basement apartments.

In the videos, MRNY members in Queens, including households whose homes were impacted by Hurricane Ida, share their experiences with housing insecurity, as well as dealing with the effects of the pandemic and the flood loss caused by Ida. Such testimonials underscore the ways in which a public health crisis and natural disasters can exacerbate housing insecurity.