riprap / flood-exposure briefing NYC
methodology gallery

Flood-exposure briefing, address

4970 Broadway, Manhattan, NY

Briefing for: 4970 Broadway, Inwood, Manhattan Snapshot 2026-10-05 How this briefing was made 1 source failed to respond

This address is outside the 2012 Sandy inundation footprint,1 in FEMA flood zone X (an area of minimal flood hazard) on the 2007 effective map,2 and outside every flooding category on the city's stormwater flood maps (modelled scenarios, not forecasts) for current, 2050 and 2080 sea-level rise.3456 Outside a mapped extent does not mean safe: NYC Emergency Management reports that during Hurricane Ida in 2021 "The most heavily impacted areas, representing over half of all damaged buildings, were also outside of any flood risk scenario, including FEMA floodplain maps and the NYC Stormwater Resiliency Plan's Extreme and Moderate stormwater scenarios" (NYC Hazard Mitigation Plan, flooding profile, nychazardmitigation.com).3456 20 complaints to 311 about flooding and sewer backups were filed within 200 m in the last 5 years, since 2021-10-06 (a count of reports; a low count can mean under-reporting, not the absence of flooding).7

Evidence

SourceFindingFigureTierData as ofCite
Behind the summary
NYC Open Data
Outside the empirical 2012 Hurricane Sandy inundation footprint (NYC Open Data). NYC Sandy Inundation Zone (2012 empirical extent)
Measured 2015-11-09 1
FEMA National Flood Hazard Layer (NFHL)
In FEMA flood zone X (an area of minimal flood hazard) on FEMA's effective flood map (FIRM panel 3604970081F, effective 2007-09-05), the map in force for the National Flood Insurance Program. FEMA National Flood Hazard Layer, flood zone at this point
Modeled 2007-09-05 2
NYC Stormwater Flood Maps (method of the 2021 Stormwater Resiliency Plan; Open Data files of 2024)
  • The city's stormwater flood map "Limited Flood (1.77 inches/hr) with Current Sea Levels" (the near term) shows no flooding category at the point mapped for this address. The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts: their rainfall flooding categories cover public areas and rain only, the city says the map "does not provide the exact depth of flooding at any location", and it is not a flood plain determination. The city's Stormwater Resiliency Plan (2021) calls its moderate storm "the 10-year storm, with approximately 10 percent chance of occurrence in any given year" and its extreme storm "the 100-year storm, with approximately 1 percent chance of occurrence in any given year". Outside a mapped extent does not mean safe: NYC Emergency Management reports that during Hurricane Ida in 2021 "The most heavily impacted areas, representing over half of all damaged buildings, were also outside of any flood risk scenario, including FEMA floodplain maps and the NYC Stormwater Resiliency Plan's Extreme and Moderate stormwater scenarios" (NYC Hazard Mitigation Plan, flooding profile, nychazardmitigation.com).3
  • The city's stormwater flood map "Moderate Flood (2.13 inches/hr) with Current Sea Levels" (the near term) shows no flooding category at the point mapped for this address. The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts: their rainfall flooding categories cover public areas and rain only, the city says the map "does not provide the exact depth of flooding at any location", and it is not a flood plain determination. The city's Stormwater Resiliency Plan (2021) calls its moderate storm "the 10-year storm, with approximately 10 percent chance of occurrence in any given year" and its extreme storm "the 100-year storm, with approximately 1 percent chance of occurrence in any given year". Outside a mapped extent does not mean safe: NYC Emergency Management reports that during Hurricane Ida in 2021 "The most heavily impacted areas, representing over half of all damaged buildings, were also outside of any flood risk scenario, including FEMA floodplain maps and the NYC Stormwater Resiliency Plan's Extreme and Moderate stormwater scenarios" (NYC Hazard Mitigation Plan, flooding profile, nychazardmitigation.com).4
  • The city's stormwater flood map "Moderate Flood (2.13 inches/hr) with 2050 Sea Level Rise" shows no flooding category at the point mapped for this address. The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts: their rainfall flooding categories cover public areas and rain only, the city says the map "does not provide the exact depth of flooding at any location", and it is not a flood plain determination. The city's Stormwater Resiliency Plan (2021) calls its moderate storm "the 10-year storm, with approximately 10 percent chance of occurrence in any given year" and its extreme storm "the 100-year storm, with approximately 1 percent chance of occurrence in any given year". Outside a mapped extent does not mean safe: NYC Emergency Management reports that during Hurricane Ida in 2021 "The most heavily impacted areas, representing over half of all damaged buildings, were also outside of any flood risk scenario, including FEMA floodplain maps and the NYC Stormwater Resiliency Plan's Extreme and Moderate stormwater scenarios" (NYC Hazard Mitigation Plan, flooding profile, nychazardmitigation.com).5
  • The city's stormwater flood map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise" shows no flooding category at the point mapped for this address. The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts: their rainfall flooding categories cover public areas and rain only, the city says the map "does not provide the exact depth of flooding at any location", and it is not a flood plain determination. The city's Stormwater Resiliency Plan (2021) calls its moderate storm "the 10-year storm, with approximately 10 percent chance of occurrence in any given year" and its extreme storm "the 100-year storm, with approximately 1 percent chance of occurrence in any given year". Outside a mapped extent does not mean safe: NYC Emergency Management reports that during Hurricane Ida in 2021 "The most heavily impacted areas, representing over half of all damaged buildings, were also outside of any flood risk scenario, including FEMA floodplain maps and the NYC Stormwater Resiliency Plan's Extreme and Moderate stormwater scenarios" (NYC Hazard Mitigation Plan, flooding profile, nychazardmitigation.com).6
 Modeled 2024-07-03
NYC 311 Service Requests (NYC Open Data)
20 NYC 311 complaints about flooding and sewer backups filed within 200 m of this location in the last 5 years (since 2021-10-06; eleven descriptors; other sewer complaints, such as odors or missing covers, are not counted): 18 catch basin, 2 sewer backup. A count of complaints is a count of reports filed, not of floods: a low count can mean under-reporting and not the absence of flooding, because the propensity to file a 311 request varies with income, language and demographics (studies of other 311 complaint types: Kontokosta, Hong and Korsberg, arXiv:1710.02452; Boxer, Hong, Kontokosta and Neill, Annals of Applied Statistics 19(2), 2025, doi:10.1214/24-AOAS2003). NYC 311 complaints about flooding and sewer backups (5y)
20 complaints Proxy 2026-10-05 7
Mapped hazards (Cornerstone)
FEMA Preliminary National Flood Hazard Layer (Prelim_NFHL)
FEMA's preliminary flood map (PFIRM issued 2015-01-30, community 360497) places this address in zone X (an area of minimal flood hazard). A preliminary map is not the effective map and does not set flood insurance. New York City applies whichever of the 2015 preliminary maps or the 2007 effective maps is more restrictive for Building Code and zoning purposes, and FEMA uses the 2007 effective maps for the National Flood Insurance Program (NYC Hazard Mitigation Plan, flooding profile). FEMA preliminary flood map (PFIRM), flood zone at this point
Modeled 2015-01-30 8
USGS STN
USGS surveyed 4 Hurricane Ida high-water marks within 800 m of this address; the highest stood 1.95 ft above ground. Nearest mark: Northwest of intersection of Indian Rd. and West 218th St., at cut channel of the Harlem River, Inwood Hill Park, Manhattan (635 m away, 0.0 ft above ground). Hurricane Ida 2021, USGS high-water marks
Measured retrieved 2026-07-11 9
USGS 3DEP DEM (precomputed citywide GeoTIFF, WGS84)
Elevation about 11 m (NAVD88), read from one cell about 22 m across of the USGS 3DEP elevation model (a cell holds one value for all the ground in it, and a survey point can differ from it by a metre or more); this point is higher than 50% of the ground within 200 m (the 50th percentile; a low percentile means a local low spot where water collects). LiDAR / DEM-derived micro-topography
11.1 m Elevation Proxy retrieved 2026-07-11 10
NYC Land Cover 2017
New York City's 2017 land cover map (6 inch, from LiDAR and aerial imagery) shows that 70.5% of the ground within 500 m of this address is paved or built over and 28.6% is green (23.9% tree canopy). NYC Land Cover 2017 (6 inch), tree canopy and paved share Figure: 23.9% tree canopy, 70.5% paved or built (2017)
 23.9% tree canopy Measured 2017 11
Places and facilities (Keystone)
MTA
21 MTA subway entrances within 800 m of this address (each entrance read at its own point on the maps, with no buffer); of the nearest 8: 0 inside the 2012 Sandy inundation extent at their mapped points, 1 more within 50 m of the extent's mapped edge, and 0 inside the DEP stormwater map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise", a modelled scenario. Outside the 2012 Sandy extent but within 50 m of its mapped edge (the outline is not exact to a building), by station: 207 St (1) (388 m). The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts: their rainfall flooding categories cover public areas and rain only, the city says the map "does not provide the exact depth of flooding at any location", and it is not a flood plain determination. MTA subway/rail entrances exposed nearby
Measured 2025-12-05 12
NYCHA developments register
1 NYCHA development inside a mapped flood extent within 2000 m of this address (the register lists only developments with 10% or more of their mapped outline inside the 2012 Sandy extent, or their centre point inside one of three modeled DEP stormwater scenarios (Moderate Flood with current and with 2050 sea levels, Extreme Flood with 2080; the Limited Flood map is not tested), not every development): 1 inside the 2012 Sandy inundation extent and 0 inside the DEP stormwater map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise", a modelled scenario. Inside the 2012 Sandy extent: DYCKMAN (793 m). The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts: their rainfall flooding categories cover public areas and rain only, the city says the map "does not provide the exact depth of flooding at any location", and it is not a flood plain determination. NYCHA developments exposed nearby
Measured retrieved 2026-05-01 13
NYC Department of Education
1 public school inside a mapped flood extent within 1500 m of this address (from the NYC Department of Education's school locations for the 2019 to 2020 school year, charter schools included; the register lists only schools whose location point is inside the 2012 Sandy extent or one of three modeled DEP stormwater scenarios (Moderate Flood with current and with 2050 sea levels, Extreme Flood with 2080; the Limited Flood map is not tested), not every school): 0 inside the 2012 Sandy inundation extent at its mapped point, 4 more within 50 m of the extent's mapped edge, and 1 inside the DEP stormwater map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise", a modelled scenario (1 in a rainfall flooding category and 0 in its future high tides category, which is coastal tidal inundation projected for 2080 and not rainfall flooding). Outside the 2012 Sandy extent but within 50 m of its mapped edge (the outline is not exact to a building): P.S. 005 Ellen Lurie (1166 m), Bronx Engineering and Technology Academy (1211 m), In-Tech Academy (M.S. / High School 368) (1226 m), P.S. 310 Marble Hill (1309 m). In a rainfall flooding category of the modelled "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise" map: P.S. 152 Dyckman Valley (1113 m). The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts: their rainfall flooding categories cover public areas and rain only, the city says the map "does not provide the exact depth of flooding at any location", and it is not a flood plain determination. Public schools exposed nearby
Measured 2019-09-04 14
NYS DOH hospitals register
3 hospitals within 3000 m of this address (each read at the one point the state file gives for it, not across its campus): 0 inside the 2012 Sandy inundation extent and 0 inside the DEP stormwater map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise", a modelled scenario. The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts: their rainfall flooding categories cover public areas and rain only, the city says the map "does not provide the exact depth of flooding at any location", and it is not a flood plain determination. NYS DOH hospitals exposed nearby
Measured retrieved 2026-07-11 15
Live readings (Touchstone)
FloodNet (New York University and The City University of New York)
4 FloodNet sensors within 600 m have recorded 6 flood events (each a series of depth readings above 10 mm at the sensor, FloodNet's definition) on 5 separate days since 2024-07-02, the earliest install date among them (the latest is 2025-10-31), the most recent starting 2026-08-20 21:44 UTC (every date here is a UTC day). By UTC calendar year: 2 in 2024, 2 in 2025 and 2 in 2026. FloodNet's API lists 2 more events labelled flood here that are still to be verified by a person; Riprap counts verified events only. No event that FloodNet's API labels a flood was open at them when this was read (2026-10-05 17:33 UTC); an event under way may not be labelled yet, and FloodNet's dashboard (dataviz.floodnet.nyc) shows the current readings. The highest depth in FloodNet's record for these sensors in that period is 126 mm (5.0 in) on 2025-10-30, in an event the API marks as verified by a person, at a sensor listed as "good" in FloodNet's API when this was read (2026-10-05). FloodNet ultrasonic depth sensors (NYC)
4 Sensors nearby Measured fetched 2026-10-05 17:33 UTC 16
National Weather Service (NOAA)
Latest METAR at LaGuardia Airport, NY (10.4 km away): partly cloudy, 21.0°C, no precipitation reported, observed 2026-10-05 17:05 UTC. NWS hourly METAR observations (nearest station)
Measured fetched 2026-10-05 17:33 UTC 17
NOAA CO-OPS
Latest reading at Kings Point, NY, the nearest NOAA tide station in a straight line (14.5 km away, on Long Island Sound): 1.26 ft above MLLW (+0.13 ft vs predicted tide), observed 2026-10-05 17:24 UTC. NOAA tide-gauge water level (nearest station) Figure: Observed water level
 1.26 ft above MLLW Measured fetched 2026-10-05 17:33 UTC 18
Projections (Lodestone)
National Weather Service (NOAA)
No active NWS flood, coastal or tropical storm alerts at this point, checked 2026-10-05 17:33 UTC. NWS active alerts (flood/coastal/tropical storm)
Modeled fetched 2026-10-05 17:33 UTC 19
NWS National Water Prediction Service
The National Weather Service forecasts a peak water level of 9.1 ft above MLLW at Kings Point, the nearest forecast gauge (14 km away), on 2026-10-08 15:00 UTC (forecast issued 2026-10-05 07:33 UTC), below the gauge's minor flood stage of 10.0 ft. NWS water-level forecast (nearest harbor gauge) Figure: Forecast peak water level
 9.1 ft above MLLW Modeled fetched 2026-10-05 17:33 UTC 20
NPCC4
NPCC4 (2024) projects sea-level rise in New York City of 14 to 19 in (0.36 to 0.48 m) by the 2050s and 30 to 50 in (0.76 to 1.27 m) by 2100, relative to 1995-2014, as its middle range (25th to 75th percentile); the 90th percentile is 23 in (0.58 m) by the 2050s and 65 in (1.65 m) by 2100. NPCC4 (2024) sea-level rise projections
Modeled 2024 21
Experimental sources (1)
SourceFindingFigureTierData as ofCite
NYC land-cover model (Riprap, experimental) on Copernicus Sentinel-2 Experimental
Experimental: a satellite land-cover model estimates that 68.2% of the ground within 500 m of this address is paved or built over and 29.9% is green (20.9% tree canopy), on Sentinel-2 scenes from 2026 (1.7% bare soil or sand); no change between years is read from it. Limits: it estimates the share of each 10 m satellite pixel that is canopy, grass, paving, roof, water or bare ground, learned from the city's 2017 six-inch map, so detail finer than about 30 m is blurred and a tree over a street counts as canopy; against The Nature Conservancy's 2021 six-inch map of the city, on squares it never trained on, it read a typical district's paved share 1.7 points above the map's (at most 7.8 points off in the 46 districts with enough test ground) and its mean error per land-cover group was 4.8 points at best, more than the 3.0 points of the city's 2017 map read as if it were 2021, so the 2017 map is the more accurate source for its year; citywide its maps show 4.2 to 5.0 points less tree canopy than the city's 2017 map in 3 of its 4 yearly maps (2018, 2021, 2026) and 3.2 points more in 1 of its 4 yearly maps (2024), which is the model and its images and not the trees, so its canopy share can be several points off; two images of one summer differ by under 2.0 points in a district's paved share 19 times in 20, but between 2018 and 2024 the shares of 49 of 59 districts differ by more, so its maps of different years are not compared. Rely on the city's 2017 land cover map and The Nature Conservancy's 2021 map (both 6 inch) and the city's building footprints for a survey. Land cover from satellite, NYC land-cover model (experimental) Figure: 68.2% paved or built, 29.9% green, 20.9% tree canopy (2026)
 68.2% paved or built Modeled 2026 22

The written briefing, section by section

Mapped hazards

This address sits outside the empirical 2012 Hurricane Sandy inundation footprint (NYC Open Data).1 This address sits in FEMA flood zone X (an area of minimal flood hazard) on FEMA's effective flood map (FIRM panel 3604970081F, effective 2007-09-05), the map in force for the National Flood Insurance Program.2 FEMA's preliminary flood map (PFIRM issued 2015-01-30, community 360497) places this address in zone X (an area of minimal flood hazard).8 A preliminary map is not the effective map and does not set flood insurance. New York City applies whichever of the 2015 preliminary maps or the 2007 effective maps is more restrictive for Building Code and zoning purposes, and FEMA uses the 2007 effective maps for the National Flood Insurance Program (NYC Hazard Mitigation Plan, flooding profile).8 The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts; at the point mapped for this address they show: "Limited Flood (1.77 inches/hr) with Current Sea Levels" (the near term), no flooding category;3 "Moderate Flood (2.13 inches/hr) with Current Sea Levels" (the near term), no flooding category;4 "Moderate Flood (2.13 inches/hr) with 2050 Sea Level Rise", no flooding category;5 "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise", no flooding category.6 Their rainfall flooding categories cover public areas and rain only, and the city says the map "does not provide the exact depth of flooding at any location"; it is not a flood plain determination. The city's Stormwater Resiliency Plan (2021) calls its moderate storm "the 10-year storm, with approximately 10 percent chance of occurrence in any given year" and its extreme storm "the 100-year storm, with approximately 1 percent chance of occurrence in any given year". Outside a mapped extent does not mean safe: NYC Emergency Management reports that during Hurricane Ida in 2021 "The most heavily impacted areas, representing over half of all damaged buildings, were also outside of any flood risk scenario, including FEMA floodplain maps and the NYC Stormwater Resiliency Plan's Extreme and Moderate stormwater scenarios" (NYC Hazard Mitigation Plan, flooding profile, nychazardmitigation.com).3456 USGS surveyed 4 Hurricane Ida high-water marks within 800 m of this address; the highest stood 1.95 ft above ground.9 Nearest mark: Northwest of intersection of Indian Rd. and West 218th St., at cut channel of the Harlem River, Inwood Hill Park, Manhattan (635 m away, 0.0 ft above ground).9 Elevation about 11 m (NAVD88), read from one cell about 22 m across of the USGS 3DEP elevation model (a cell holds one value for all the ground in it, and a survey point can differ from it by a metre or more); this point is higher than 50% of the ground within 200 m (the 50th percentile; a low percentile means a local low spot where water collects).10

Live readings

4 FloodNet sensors within 600 m have recorded 6 flood events (each a series of depth readings above 10 mm at the sensor, FloodNet's definition) on 5 separate days since 2024-07-02, the earliest install date among them (the latest is 2025-10-31), the most recent starting 2026-08-20 21:44 UTC (every date here is a UTC day).16 By UTC calendar year: 2 in 2024, 2 in 2025 and 2 in 2026.16 FloodNet's API lists 2 more events labelled flood here that are still to be verified by a person; Riprap counts verified events only.16 No event that FloodNet's API labels a flood was open at them when this was read (2026-10-05 17:33 UTC); an event under way may not be labelled yet, and FloodNet's dashboard (dataviz.floodnet.nyc) shows the current readings.16 The highest depth in FloodNet's record for these sensors in that period is 126 mm (5.0 in) on 2025-10-30, in an event the API marks as verified by a person, at a sensor listed as "good" in FloodNet's API when this was read (2026-10-05).16 20 NYC 311 complaints about flooding and sewer backups filed within 200 m of this location in the last 5 years (since 2021-10-06; eleven descriptors; other sewer complaints, such as odors or missing covers, are not counted): 18 catch basin, 2 sewer backup.7 A count of complaints is a count of reports filed, not of floods: a low count can mean under-reporting and not the absence of flooding, because the propensity to file a 311 request varies with income, language and demographics (studies of other 311 complaint types: Kontokosta, Hong and Korsberg, arXiv:1710.02452; Boxer, Hong, Kontokosta and Neill, Annals of Applied Statistics 19(2), 2025, doi:10.1214/24-AOAS2003).7

Places and facilities

21 MTA subway entrances within 800 m of this address (each entrance read at its own point on the maps, with no buffer); of the nearest 8: 0 inside the 2012 Sandy inundation extent at their mapped points, 1 more within 50 m of the extent's mapped edge, and 0 inside the DEP stormwater map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise", a modelled scenario.12 Outside the 2012 Sandy extent but within 50 m of its mapped edge (the outline is not exact to a building), by station: 207 St (1) (388 m).12 1 NYCHA development inside a mapped flood extent within 2000 m of this address (the register lists only developments with 10% or more of their mapped outline inside the 2012 Sandy extent, or their centre point inside one of three modeled DEP stormwater scenarios (Moderate Flood with current and with 2050 sea levels, Extreme Flood with 2080; the Limited Flood map is not tested), not every development): 1 inside the 2012 Sandy inundation extent and 0 inside the DEP stormwater map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise", a modelled scenario.13 Inside the 2012 Sandy extent: DYCKMAN (793 m).13 1 public school inside a mapped flood extent within 1500 m of this address (from the NYC Department of Education's school locations for the 2019 to 2020 school year, charter schools included; the register lists only schools whose location point is inside the 2012 Sandy extent or one of three modeled DEP stormwater scenarios (Moderate Flood with current and with 2050 sea levels, Extreme Flood with 2080; the Limited Flood map is not tested), not every school): 0 inside the 2012 Sandy inundation extent at its mapped point, 4 more within 50 m of the extent's mapped edge, and 1 inside the DEP stormwater map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise", a modelled scenario (1 in a rainfall flooding category and 0 in its future high tides category, which is coastal tidal inundation projected for 2080 and not rainfall flooding).14 Outside the 2012 Sandy extent but within 50 m of its mapped edge (the outline is not exact to a building): P.S. 005 Ellen Lurie (1166 m), Bronx Engineering and Technology Academy (1211 m), In-Tech Academy (M.S. / High School 368) (1226 m), P.S. 310 Marble Hill (1309 m).14 In a rainfall flooding category of the modelled "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise" map: P.S. 152 Dyckman Valley (1113 m).14 3 hospitals within 3000 m of this address (each read at the one point the state file gives for it, not across its campus): 0 inside the 2012 Sandy inundation extent and 0 inside the DEP stormwater map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise", a modelled scenario.15 The city's stormwater flood maps are modelled scenarios (each a design storm paired with a sea level), not forecasts: their rainfall flooding categories cover public areas and rain only, the city says the map "does not provide the exact depth of flooding at any location", and it is not a flood plain determination.12131415

Projections

No active NWS flood, coastal or tropical storm alerts at this point, checked 2026-10-05 17:33 UTC.19 NPCC4 (2024) projects sea-level rise in New York City of 14 to 19 in (0.36 to 0.48 m) by the 2050s and 30 to 50 in (0.76 to 1.27 m) by 2100, relative to 1995-2014, as its middle range (25th to 75th percentile); the 90th percentile is 23 in (0.58 m) by the 2050s and 65 in (1.65 m) by 2100.21

Not checked

These sources were consulted at 2026-10-05 17:33 UTC and did not answer, so nothing above is a reading of them and their silence is not an absence: USGS stream gauge, live stage at the nearest gauge.

This is an automated hazard-exposure briefing produced by Riprap from live and precomputed data sources. It is informational only and not a substitute for a professional risk assessment. These are public records about a place, not an assessment of any property or of the people who live there. Riprap computes no score or rating, and records can be missing where people report less.

Live here or own property here? FloodHelpNY explains flood zones and insurance for New York City residents.

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Figure 1. Plotted: 4 Ida high-water marks (amber), measured; 20 complaints to 311, each placed at its block and not at a house (hollow rings, proxy); 17 public assets from the register. Search radii (rings): high-water marks 800 m, FloodNet sensors 600 m, 311 complaints 200 m. FloodNet's sensors are not drawn on this page; they are shown on FloodNet's own dashboard.
Map layers
Map points as a list (41)

Sources and method

Sources cited

All 22 sources, with titles and document ids
  1. 1 NYC Open Data, Sandy Inundation Zone NYC Sandy Inundation Zone (NYC Open Data 5xsi-dfpx, empirical 2012 extent) Measured, data as of 2015-11-09, sandy_inundation
  2. 2 FEMA National Flood Hazard Layer (NFHL), effective flood zones FEMA NFHL effective flood-zone polygon and FIRM panel intersecting the address point. Modeled, data as of 2007-09-05, fema_nfhl
  3. 3 NYC Stormwater Flood Maps (method of the 2021 Stormwater Resiliency Plan; Open Data files of 2024), Limited Flood (1.77 inches/hr) with Current Sea Levels NYC Stormwater Flood Maps (NYC Open Data 9i7c-xyvv, Department of Environmental Protection), map "Limited Flood (1.77 inches/hr) with Current Sea Levels". Riprap reads this map from the vector tiles of DEP's own map viewer (nyc.gov/stormwater-map, tile service Moderate_5yearMHHW_updateOB_VTile1_61424), because the NYC Open Data file for it is a compressed geodatabase that open tools cannot read; the other three maps are read from the NYC Open Data files. The viewer's tiles and the Open Data files are not identical where both can be read (for the Moderate map with current sea levels the deep and contiguous category matches and the nuisance category differs by about a tenth of its area), so this reading may differ from the Open Data file for the Limited map. Map disclaimer, from DEP's own map items (arcgis.com/home/item.html?id=5b82c08be55d4f30bf28d265ab8e4a49): the map "is intended to be an informational tool and does not provide the exact depth of flooding at any location", shows "the relative risk of flooding in public areas from stormwater runoff due to rain only", and "shall not be used for the design, modification, or construction of improvements to real property or for flood plain determination". The caveat on an outside reading quotes NYC Emergency Management, Hazard Mitigation Plan, flooding profile (https://nychazardmitigation.com/documentation/hazard-profiles/flooding/). Modeled, data as of 2024-07-03, dep_limited_current
  4. 4 NYC Stormwater Flood Maps (method of the 2021 Stormwater Resiliency Plan; Open Data files of 2024), Moderate Flood (2.13 inches/hr) with Current Sea Levels NYC Stormwater Flood Maps (NYC Open Data 9i7c-xyvv, Department of Environmental Protection), map "Moderate Flood (2.13 inches/hr) with Current Sea Levels". Map disclaimer, from DEP's own map items (arcgis.com/home/item.html?id=5b82c08be55d4f30bf28d265ab8e4a49): the map "is intended to be an informational tool and does not provide the exact depth of flooding at any location", shows "the relative risk of flooding in public areas from stormwater runoff due to rain only", and "shall not be used for the design, modification, or construction of improvements to real property or for flood plain determination". The caveat on an outside reading quotes NYC Emergency Management, Hazard Mitigation Plan, flooding profile (https://nychazardmitigation.com/documentation/hazard-profiles/flooding/). Modeled, data as of 2024-07-03, dep_moderate_current
  5. 5 NYC Stormwater Flood Maps (method of the 2021 Stormwater Resiliency Plan; Open Data files of 2024), Moderate Flood (2.13 inches/hr) with 2050 Sea Level Rise NYC Stormwater Flood Maps (NYC Open Data 9i7c-xyvv, Department of Environmental Protection), map "Moderate Flood (2.13 inches/hr) with 2050 Sea Level Rise". The Stormwater Resiliency Plan (2021) describes its moderate scenario as "approximately two inches of rain falling in one hour (also referred to as the 10-year storm, with approximately 10 percent chance of occurrence in any given year) combined with 2.5 feet of SLR". Map disclaimer, from DEP's own map items (arcgis.com/home/item.html?id=5b82c08be55d4f30bf28d265ab8e4a49): the map "is intended to be an informational tool and does not provide the exact depth of flooding at any location", shows "the relative risk of flooding in public areas from stormwater runoff due to rain only", and "shall not be used for the design, modification, or construction of improvements to real property or for flood plain determination". The caveat on an outside reading quotes NYC Emergency Management, Hazard Mitigation Plan, flooding profile (https://nychazardmitigation.com/documentation/hazard-profiles/flooding/). Modeled, data as of 2024-07-03, dep_moderate_2050
  6. 6 NYC Stormwater Flood Maps (method of the 2021 Stormwater Resiliency Plan; Open Data files of 2024), Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise NYC Stormwater Flood Maps (NYC Open Data 9i7c-xyvv, Department of Environmental Protection), map "Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise". The Stormwater Resiliency Plan (2021) describes its extreme scenario as "approximately 3.5 inches of rain falling in one hour (also referred to as the 100-year storm, with approximately 1 percent chance of occurrence in any given year) combined with 4.8 feet of SLR". Map disclaimer, from DEP's own map items (arcgis.com/home/item.html?id=5b82c08be55d4f30bf28d265ab8e4a49): the map "is intended to be an informational tool and does not provide the exact depth of flooding at any location", shows "the relative risk of flooding in public areas from stormwater runoff due to rain only", and "shall not be used for the design, modification, or construction of improvements to real property or for flood plain determination". The caveat on an outside reading quotes NYC Emergency Management, Hazard Mitigation Plan, flooding profile (https://nychazardmitigation.com/documentation/hazard-profiles/flooding/). Modeled, data as of 2024-07-03, dep_extreme_2080
  7. 7 NYC 311 Service Requests (NYC Open Data) NYC 311 Service Requests from 2020 to Present (NYC Open Data dataset erm2-nwe9), complaints about flooding and sewer backups within 200 m of the point. Counted: requests of complaint type "Sewer" or "Sewer Maintenance" whose descriptor is one of eleven flood and sewer descriptors (street flooding, sewer backup, catch basin, highway flooding, manhole overflow and rain garden flooding, under their coded and plain names; the list is in app/context/nyc311.py), created on or after the start date the sentence gives (midnight UTC, 365 days for each year of the window). A request filed under both descriptor names at the same place within ten minutes is counted once. This citation's query_url is the Socrata query for the counted rows, with no house number or coordinate selected. Complaints are shown at the block, never the house number. Proxy, data as of 2026-10-05, nyc311, the query for these rows
  8. 8 FEMA Preliminary National Flood Hazard Layer (Prelim_NFHL), preliminary flood zones FEMA preliminary flood-zone polygon (PFIRM) intersecting the address point, with the issue date from the service's Preliminary Data Availability layer. Which map is used for what is from the NYC Hazard Mitigation Plan, flooding profile (https://nychazardmitigation.com/documentation/hazard-profiles/flooding/): "New York City applies whichever map (2015 PFIRMs or 2007 FIRMs) is the more restrictive of the two for Building Code and zoning purposes" and "FEMA uses the 2007 FIRMs for compliance with NFIP". Modeled, data as of 2015-01-30, fema_pfirm
  9. 9 USGS STN, Hurricane Ida 2021 (Event 312, NY) USGS STN Hurricane Ida 2021 high-water marks (Event 312, NY). The link is the STN web-service query that returns these marks; the retired STN Data Portal page no longer exists. Measured, retrieved 2026-07-11, ida_hwm
  10. 10 USGS 3DEP DEM (precomputed citywide GeoTIFF, WGS84) USGS 3DEP DEM: the 3D Elevation Program's elevation model, read from the 3DEP elevation service (scripts/fetch_nyc_dem.py) and stored in WGS84, where a cell is about 22 m east to west and 29 m north to south; heights are NAVD88. The service mosaics the best available surveys and the file carries no survey date, so the date shown is when Riprap's copy was made. One cell holds one value for all the ground in it: a survey point can differ from it by a metre or more. Proxy, retrieved 2026-07-11, microtopo
  11. 11 NYC Land Cover 2017, 6 inch (NYC Office of Technology and Innovation; University of Vermont Spatial Analysis Lab) Land Cover Raster Data (2017), 6 inch resolution, NYC Open Data he6d-2qns: eight classes mapped from 2017 LiDAR and aerial imagery. Riprap counts the 6 inch pixels of each class into 30 m cells and reports the shares within 500 m of the address; a tree over a street counts as canopy. Measured, data as of 2017, city_landcover
  12. 12 MTA, subway/rail entrances register MTA subway/rail entrances, cross-referenced with Sandy 2012 + DEP extreme 2080. Measured, data as of 2025-12-05, mta_entrance_exposure
  13. 13 NYCHA developments register NYCHA public housing developments, cross-referenced with Sandy 2012 + DEP extreme 2080. Measured, retrieved 2026-05-01, nycha_development_exposure
  14. 14 NYC Department of Education, 2019 - 2020 School Point Locations (public schools, charter schools included) NYC public schools, charter schools included (2019 to 2020 school locations), cross-referenced with Sandy 2012 + DEP extreme 2080. Measured, data as of 2019-09-04, doe_school_exposure
  15. 15 NYS DOH hospitals register NYS DOH Health Facility General Information (vn5v-hh5r) hospitals in NYC, cross-referenced with Sandy 2012 + DEP extreme 2080. Measured, retrieved 2026-07-11, doh_hospital_exposure
  16. 16 FloodNet (New York University and The City University of New York) FloodNet street flood sensors. Flood events and sensor status read from the FloodNet Data API (api.floodnet.nyc, an early-access beta) at the retrieval time shown. A flood event is a series of depth measurements greater than 10 mm at the sensor (FloodNet's definition); a depth is measured at one point and does not show the depth on every part of the street. Riprap counts the events the API marks as verified by a person. FloodNet's published cautions about a depth: "most FloodNet sensors are mounted over sidewalks and are thus unable to measure floods in the roadbed until the water rises above the height of the curb"; the depth at the street's lowest point differs from the reading by the sensor's height above that point; "a single anomalous data point, measured during a flood event" may exaggerate a maximum depth; and a sensor may miss a flood "if it was offline and awaiting repair or had not been deployed yet or retired" (FloodNet's NYC Open Data description, dataset aq7i-eu5q). Ten rows of FloodNet's deployments table are NOAA and USGS tide gauges (deploy_type "tidal"); Riprap does not count them as FloodNet sensors. Riprap names no sensor, because FloodNet's licence forbids reposting its records: each verified event can be found by its date and depth in FloodNet's own table on NYC Open Data, "FloodNet: Street Flooding Events Measured by FloodNet Sensors" (https://data.cityofnewyork.us/d/aq7i-eu5q), and on its dashboard (https://dataviz.floodnet.nyc). Cite: Mydlarz et al. (2024), Water Resources Research 60, e2023WR036806, https://doi.org/10.1029/2023WR036806; Silverman et al. (2022), Water Research, 118648, https://doi.org/10.1016/j.watres.2022.118648. Licence: FloodNet data and content derived from it are CC BY-NC-SA 4.0 (https://creativecommons.org/licenses/by-nc-sa/4.0/), not Riprap's Apache-2.0. Riprap is independent of FloodNet and not endorsed by it. Measured, fetched 2026-10-05 17:33 UTC, floodnet
  17. 17 National Weather Service (NOAA), nearest METAR station NWS hourly METAR observations, nearest station to address. Measured, fetched 2026-10-05 17:33 UTC, nws_obs
  18. 18 NOAA CO-OPS, tide gauge water level (nearest station) NOAA CO-OPS tide-gauge water level observations, nearest station to address. Measured, fetched 2026-10-05 17:33 UTC, noaa_tides
  19. 19 National Weather Service (NOAA), active alerts at point NWS active alerts at address (flood / coastal / tropical storm). Modeled, fetched 2026-10-05 17:33 UTC, nws_alerts
  20. 20 NWS National Water Prediction Service, gauge forecast National Weather Service, National Water Prediction Service, official water-level forecast and flood stages for the nearest harbor gauge. Modeled, fetched 2026-10-05 17:33 UTC, nws_water_forecast
  21. 21 NPCC4, New York City Panel on Climate Change (2024) Braneon, C. et al. (2024). NPCC4: New York City climate risk information 2022, observations and projections. Annals of the New York Academy of Sciences, Vol. 1539 (doi:10.1111/nyas.15116), Table 1: projections for sea level rise in New York City, relative to 1995-2014. Modeled, data as of 2024, npcc4_slr
  22. 22 NYC land-cover model (Riprap, experimental) on Copernicus Sentinel-2, trained on NYC Land Cover 2017 Riprap's NYC land-cover model, trained by scripts/train_cover.py on NYC Land Cover 2017 (6 inch, NYC Open Data) aggregated to 10 m and run by scripts/run_landcover_batch.py on Sentinel-2 L2A scenes; scored against NYC Land Cover 2021 (The Nature Conservancy and UVM) on squares it never trained on. Contains modified Copernicus Sentinel data, via Microsoft Planetary Computer. Experimental: an estimate from 10 m pixels, not a survey. Modeled Experimental, data as of 2026, landcover

What was checked

Sources consulted (23), 1 failed to respond
  • USGS stream gauge, live stage at the nearest gauge: failed to respond
  • NYC Sandy Inundation Zone (2012 empirical extent)
  • FEMA National Flood Hazard Layer, flood zone at this point
  • FEMA preliminary flood map (PFIRM), flood zone at this point
  • NYC Stormwater Flood Map - Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise
  • NYC Stormwater Flood Map - Moderate Flood (2.13 inches/hr) with 2050 Sea Level Rise
  • NYC Stormwater Flood Map - Moderate Flood (2.13 inches/hr) with Current Sea Levels
  • NYC Stormwater Flood Map - Limited Flood (1.77 inches/hr) with Current Sea Levels
  • Hurricane Ida 2021, USGS high-water marks
  • LiDAR / DEM-derived micro-topography
  • NYC Land Cover 2017 (6 inch), tree canopy and paved share
  • Land cover from satellite, NYC land-cover model (experimental)
  • FloodNet ultrasonic depth sensors (NYC)
  • NYC 311 complaints about flooding and sewer backups (5y)
  • NWS hourly METAR observations (nearest station)
  • NOAA tide-gauge water level (nearest station)
  • MTA subway/rail entrances exposed nearby
  • NYCHA developments exposed nearby
  • Public schools exposed nearby
  • NYS DOH hospitals exposed nearby
  • NWS active alerts (flood/coastal/tropical storm)
  • NWS water-level forecast (nearest harbor gauge)
  • NPCC4 (2024) sea-level rise projections

Not checked for this question: none of the sources for this kind of place were skipped.

Out of scope

This briefing is not a flood zone determination, an engineering assessment or advice. Where a probe was offline at run time, the relevant section omits that signal.

How this briefing was made

Evidence briefing (no LLM).

Precomputed snapshot, generated 2026-10-05 17:33 UTC from Riprap commit b0398f64. Live readings (tides, alerts, sensors) are as of that time.

5 Stones, 24 registered source functions: 23 ran, 1 failed.

What each source returned

Mapped hazards (Cornerstone, 11 source functions)
  • sandy Empirical: directly measured or observed NYC Sandy Inundation Zone (2012 empirical extent) inside=false 100ms
  • fema_nfhl Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) FEMA National Flood Hazard Layer, flood zone at this point zone=X, sfha=false 460ms
  • fema_pfirm Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) FEMA preliminary flood map (PFIRM), flood zone at this point zone=X, sfha=false 460ms
  • dep_extreme_2080 Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) NYC Stormwater Flood Map - Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise category_code=0 100ms
  • dep_moderate_2050 Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) NYC Stormwater Flood Map - Moderate Flood (2.13 inches/hr) with 2050 Sea Level Rise category_code=0 100ms
  • dep_moderate_current Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) NYC Stormwater Flood Map - Moderate Flood (2.13 inches/hr) with Current Sea Levels category_code=0 100ms
  • dep_limited_current Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) NYC Stormwater Flood Map - Limited Flood (1.77 inches/hr) with Current Sea Levels category_code=0 100ms
  • ida_hwm Empirical: directly measured or observed Hurricane Ida 2021, USGS high-water marks n_within_800m=4, max_height_above_gnd_ft=1.95 10ms
  • microtopo Proxy: an indirect indicator, such as reports people filed with 311; not a measurement of flooding LiDAR / DEM-derived micro-topography elev_m=11.10, pct_200m=50.10 280ms
  • city_landcover Empirical: directly measured or observed NYC Land Cover 2017 (6 inch), tree canopy and paved share 120ms
  • landcover Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) Land cover from satellite, NYC land-cover model (experimental) 140ms
Places and facilities (Keystone, 4 source functions)
  • mta_entrances Empirical: directly measured or observed MTA subway/rail entrances exposed nearby n_entrances=21, n_inside_sandy_2012=0 60ms
  • nycha_developments Empirical: directly measured or observed NYCHA developments exposed nearby n_developments=1, n_inside_sandy_2012=1 20ms
  • doe_schools Empirical: directly measured or observed Public schools exposed nearby n_schools=1, n_inside_sandy_2012=0 30ms
  • doh_hospitals Empirical: directly measured or observed NYS DOH hospitals exposed nearby n_hospitals=3, n_inside_sandy_2012=0 40ms
Live readings (Touchstone, 5 source functions)
  • floodnet Empirical: directly measured or observed FloodNet ultrasonic depth sensors (NYC) n_sensors=4, n_events_3y=6 460ms
  • nyc311 Proxy: an indirect indicator, such as reports people filed with 311; not a measurement of flooding NYC 311 complaints about flooding and sewer backups (5y) n=20 350ms
  • nws_obs Empirical: directly measured or observed NWS hourly METAR observations (nearest station) p1h_mm, p6h_mm, station=KLGA 350ms
  • noaa_tides Empirical: directly measured or observed NOAA tide-gauge water level (nearest station) observed_ft_mllw=1.26, residual_ft=0.13, station=8516945 450ms
  • usgs_gauges Empirical: directly measured or observed USGS stream gauge, live stage at the nearest gauge the service refused the request: too many requests (HTTP 429) 430ms
Projections (Lodestone, 3 source functions)
  • nws_alerts Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) NWS active alerts (flood/coastal/tropical storm) n_active=0 400ms
  • nws_water_forecast Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) NWS water-level forecast (nearest harbor gauge) forecast_peak_ft_mllw=9.10, flood_category 340ms
  • npcc4_slr Modeled: from a model, not a measurement. The row says which kind: a simulated scenario (not a forecast), a mapped zone, a forecast, or an index (a rank from a statistical model) NPCC4 (2024) sea-level rise projections 0ms
The briefing (Capstone, 1 source function)
  • step-27 reconcile_templated n_chars=10691, n_citations=22 36ms
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