Coastal / Tidal
Hazard
0.35Tidal FloodingcategoricaliChronic tidal flooding is an accelerating threat to coastal NYCHA properties. Earlier onset indicates greater near-term risk, warranting higher hazard scores for developments facing imminent tidal inundation.
0.30PFIRM FloodplainbooleaniThe FEMA Preliminary Flood Insurance Rate Map defines the current regulatory flood zone. Properties within the PFIRM are subject to flood insurance requirements and face documented flood risk under present-day conditions.
0.202050 Coastal SurgebooleaniNPCC-projected 2050s coastal surge extent captures properties that will enter the flood zone as sea levels rise, representing medium-term coastal risk.
0.152080 Coastal SurgebooleaniNPCC-projected 2080s coastal surge extent identifies properties facing long-term coastal flood risk under higher sea level rise scenarios.
Vulnerability
0.67Inhabited Floor Below Coastal DFEmin_maxiBuildings with inhabited space below the Design Flood Elevation face direct flood damage to residents and critical building systems during coastal storm events.
0.33Basements Below Coastal DFEmin_maxiBasements below the Design Flood Elevation are vulnerable to flooding damage to building mechanical systems, electrical infrastructure, and storage even when inhabited floors remain above flood level. Basement elevation estimated as grade minus 10 ft.
Mitigation
0.45Sandy Risk Reductionmin_maxiPost-Sandy resilience retrofits represent the most comprehensive flood protection program undertaken at NYCHA, including elevated equipment, floodproofing, and site-wide drainage improvements.
0.30IDA Risk Reductionmin_maxiPost-Hurricane Ida recovery work addressed stormwater and coastal vulnerabilities exposed during the 2021 storm, providing targeted flood protection improvements.
0.25Critical EquipmentcategoricaliElevating or protecting boilers, electrical switchgear, and other critical building systems above flood levels is a primary strategy for maintaining habitability during and after flood events.
All mitigation factors only scored when coastal hazard is present
MitigationEffectiveness: 0.9
Coastal Risk
(H×V)norm × (1 − 0.9 × M)
Stormwater
Hazard
0.60Stormwater 2020booleaniNYC Department of Environmental Protection (DEP) Stormwater Flood Maps under current sea levels. Properties exposed today face the most immediate stormwater risk, warranting the highest weight in this sub-index.
0.30Stormwater 2050booleaniNYC Department of Environmental Protection (DEP) Stormwater Flood Maps with 2050 sea level rise. Captures properties entering the stormwater flood zone as drainage capacity is reduced by rising groundwater and tidal levels.
0.10Stormwater 2080booleaniNYC Department of Environmental Protection (DEP) Stormwater Flood Maps under 2080 extreme scenario. Represents the broadest projected stormwater exposure, weighted lowest as it reflects longer-term conditions.
Vulnerability
0.67Inhabited Floor Below Stormwater DFEmin_maxiBuildings with inhabited space below the stormwater flood elevation are directly exposed to interior flooding from extreme rainfall events, posing risks to residents and building systems.
0.33Basements Below Stormwater DFEmin_maxiBasements below the stormwater flood elevation face flooding from extreme rainfall, threatening critical systems. Basement elevation estimated as grade minus 10 ft.
Mitigation
0.40Sandy Risk Reductionmin_maxiSandy retrofits included stormwater management improvements (drainage, backflow prevention) that reduce stormwater flood risk in addition to coastal protection.
0.25IDA Risk Reductionmin_maxiPost-Ida recovery work specifically addressed stormwater drainage failures, providing cross-domain mitigation credit for stormwater flood risk reduction.
0.20Cloudburst SitebooleaniCloudburst management sites have been designed with stormwater retention and conveyance infrastructure to manage extreme rainfall volumes on campus.
0.15Critical EquipmentcategoricaliProtected critical equipment maintains building operability during stormwater flood events, reducing the impact of basement and ground-floor flooding on residents.
All mitigation factors only scored when stormwater hazard is present
MitigationEffectiveness: 0.9
Stormwater Risk
(H×V)norm × (1 − 0.9 × M)
Groundwater
Hazard
1.00Depth to Groundwatermin_max_inviShallow groundwater tables increase risk of basement flooding, foundation damage, and sewer infiltration. Developments with groundwater closer to the surface face greater structural and operational risks.
Capped at 16 ft (≥ 16 ft = no hazard)
Vulnerability
1.00Building Agemin_maxiOlder buildings are more likely to have deteriorated waterproofing, outdated drainage systems, and foundation materials susceptible to groundwater damage.
Vulnerability only scored when groundwater hazard is present (depth < 16 ft)
Mitigation
0.45Sandy Risk Reductionmin_maxiSandy retrofits included below-grade waterproofing, foundation repairs, and drainage improvements that reduce vulnerability to chronic groundwater intrusion in addition to flood resilience.
0.30IDA Risk Reductionmin_maxiPost-Ida recovery addressed basement flooding and sewer-backup failures that are strongly correlated with shallow groundwater, providing cross-domain mitigation credit for groundwater flood risk.
0.25Critical EquipmentcategoricaliElevating critical systems above grade protects against chronic groundwater seepage and rising water tables that can damage below-grade equipment over time.
All mitigation factors only scored when groundwater hazard is present (depth < 16 ft)
MitigationEffectiveness: 0.9
Groundwater Risk
(H×V)norm × (1 − 0.9 × M)
Extreme Heat
Hazard
0.70Solar Radiation (ground)min_maxiGround-level solar exposure drives surface temperatures on NYCHA campuses. More exposed ground area means higher ambient temperatures for residents in outdoor common spaces.
0.20Mean Building Heightmin_maxiTaller buildings contribute to the urban heat island effect through greater thermal mass and reduced airflow at ground level, increasing ambient temperatures on campus.
0.10Total Roof Areamin_maxiLarger aggregate roof surfaces absorb and re-radiate solar energy, amplifying the urban heat island effect on campus. Total roof area serves as a proxy for the built mass contributing to heat retention.
Vulnerability
0.70Senior Population %min_maxiOlder adults face elevated risk of heat-related mortality due to chronic health conditions, reduced mobility, medication interactions, and social isolation that limits access to cooling.
0.30Youth Population %min_maxiChildren are physiologically more susceptible to heat-related illness due to higher metabolic rates and less effective thermoregulation, and are more dependent on caregivers for protective action.
Mitigation
0.50Cool RoofbooleaniHigh-albedo cool roofs reflect solar radiation instead of absorbing it, reducing rooftop temperatures by up to 60°F and lowering indoor cooling loads for top-floor apartments.
0.50On-site Cooling CenterbooleaniUnion of DFTA senior centers and DYCD community/youth centers on-campus. On-site cooling centers provide immediate refuge for heat-vulnerable residents during extreme heat events without requiring travel off-site.
All mitigation factors only scored when heat hazard is present
MitigationEffectiveness: 0.6
Heat Risk
(H×V)norm × (1 − 0.6 × M)