What Hurricane Ida and Superstorm Sandy taught us about flooding and health
Superstorm Sandy (2012) and rainfall from Hurricane Ida (2021) broke records in NYC and resulted in injury and death. Both showed how the climate crisis is affecting the strength of storms and how profound the threat of flooding is to New Yorkers’ health.
Superstorm Sandy’s coastal flooding damaged hundreds of thousands of homes
When Superstorm Sandy hit New York City in October 2012, 52 people died as a result of injuries and there were increases in deaths from other causes, such as chronic health conditions. Thousands of people were evacuated from hospitals, nursing homes and other facilities. Two million homes and facilities lost power. Altogether, the storm caused billions of dollars of damage to people’s homes and businesses.
The majority of the homes damaged and destroyed during Sandy were in coastal areas where higher-than-normal tides (due to time of day, sea level rise, and lunar cycles) and powerful winds combined to send water rushing onto the shoreline. This is a storm surge.
Most injury deaths during Sandy occurred at home
Most of the 52 injury deaths that were both indirectly and directly caused by Sandy took place along the coasts in Staten Island (44%), Queens (25%) and Brooklyn (23%), in zones where the mayor ordered an evacuation of residents. Not everyone chose to or was able to evacuate, and some tried to evacuate in dangerous conditions, resulting in injury and death. Almost half of those who died (48%) were ages 65 and older.
Thirty-six people drowned as a result of the flooding. At least one third of those who drowned at home (9 people) were found in the basement or lived in a basement apartment.
People with less access to resources were more vulnerable to the effects of flooding and power outages
After the storm, damage to buildings, homes and infrastructure and the interruption of essential services harmed under-resourced communities and older adults. Food pantries flooded and lost inventory. Power outages stranded older adults and those with mobility access needs in high-rises, cutting off access to medication and other essentials. Residents of public housing developments along the waterfront felt these impacts particularly strongly.
Why is coastal flooding risk increasing? As the global average temperature rises, glaciers and sea ice are melting, adding more water to the ocean. The ocean is also absorbing heat, making it take up more space. It's the same effect that happens when you can’t remove a ring in the summer because your fingers swell in the hot temperatures. As the ocean expands from these, and other factors, we get storm surges that are higher than average.
What will the future of coastal flooding look like in NYC? The sea level in NYC is rising, which makes powerful storm surges worse. Scientists warn that the sea level will rise further over the coming decades — top-range projections estimate 45 inches in the 2080s and 65 inches by 2100. We’re not sure how quickly it’ll happen and not every area of NYC will be affected equally because some areas are on higher ground or are further from the shore. Single and two-family homes and lower-level apartments and basements are at higher risk for flooding and damage.
Tidal flooding also will play a role. With climate change, tides are likely to be higher more often, causing more frequent tidal flooding. This is when high tides temporarily flood low-lying areas. Data show that there was a 200% increase in high tide flood days from 2000 to 2021. Flooding from tides that are higher than they have been historically means flooding can happen even when there is no severe weather.
Ida’s extreme rainfall broke records and flooded basement apartments
When Hurricane Ida hit New York City in September 2021, rain fell faster than it could drain away through storm water infrastructure. This caused unprecedented inland flooding, especially in low-lying areas and basement apartments. Unlike the flooding that happened during Sandy, which mostly affected coastal areas, rainfall (or pluvial) flooding can happen anywhere in the city.
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Nine inches of rain fell at an unprecedented rate per hour.
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Record-breaking 3.5 inches per hour of rainfall fell in some areas, exceeding NYC’s sewer capacity of 1.75 inches per hour
The National Weather Service issued its first-ever flash flood emergency warning for New York City. Flash flooding occurs when heavy rainfall happens in a short period of time so quickly that people are often caught off guard. Fourteen people died from causes related to Ida. Most of them (71%, or 10 deaths) by drowning in unregulated (illegal) basement apartments.
Climate change is making it rain more intensely because warmer air holds more moisture. It has rained larger amounts each year on average since 1960 in NYC.
What will the future of rainfall flooding look like in NYC?
Rainfall intensity and frequency is increasing, which is associated with inland flooding, like what we saw during Ida. Exactly how and where rainfall-based flooding will occur can be difficult to predict, but we know that low-lying areas, including basement apartments, are at higher risk. Average annual rainfall is projected to increase by a minimum of 2 – 7% by the 2030s and a maximum of 7 – 17% by the 2080s.
But it’s not just volume of rainfall that’s increasing, it’s intensity
Rainfall intensity, which is measured by an amount of rainfall that falls in a given time period, has been increasing in New York City over the last 70 years. Observations comparing rainfall intensity in Central Park since 1950 show that the amount of rain that can fall in a very short period of time, like an hour or two, has increased significantly from previous decades.
Housing and socioeconomic status were important factors for who was most at risk during Ida
Most of the people in NYC who died during Ida died in unregulated basement apartments. They were mostly Asian (71%) and born outside the U.S (71%). New Yorkers who live in these basement apartments may have limited housing options due to high housing costs. These deaths from Ida reflect how a housing crisis makes people more vulnerable to the health burden of the climate crisis. This disproportionately affects immigrants and New Yorkers living in poverty.
Both coastal and rainfall flooding are increasing in NYC…
Bottom line: Because of higher sea levels, flooding from coastal storms is likely to increase in NYC. Hurricanes with stronger winds can also make storm surges worse. Higher tides are also a contributor to the magnitude of coastal flooding.
Who is most at risk: People in neighborhoods closest to the coasts that live in evacuation zones and people with health conditions, physical environments and social contexts that make it more difficult to prepare or evacuate.
Bottom line: Flooding from more intense rainfall is likely to increase in NYC.
Who is most at risk: People living in basement apartments and lower-lying areas and people with health conditions, physical environments and social contexts that make it more difficult to prepare or evacuate.
…But flooding won’t impact everyone equally
Certain populations are more vulnerable to the health risks of flooding and may find it difficult to evacuate.
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People with chronic illnesses, older and very young people, people with disabilities or mobility impairments.
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People with less access to resources to prepare or evacuate, including people who might not receive warning information because of isolation or language barriers, people socially or economically marginalized, or people with unstable living situations.
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People with less control over their environment, such as those who are living in institutional settings or are incarcerated.
People living along the coasts with less access to resources are the most vulnerable to storm surge
The storm surge Flood Vulnerability Index (FVI) can show you the estimated risk in your area to the impacts of coastal flooding. The FVI combines risk of physical exposure to different flooding types with socioeconomic factors that increase risk of harm and affect how difficult it may be to recover. Many of these are listed above, but the index also includes factors like home ownership, which may increase the costs and time it takes to recover.
Coastal areas have the highest risk of flooding. Within coastal areas, this risk level may vary by housing type, median income, and other demographics.
The FVI is part of the Vulnerability, Impacts, and Adaptation report (VIA) and can be fully accessed as part of the EJNYC Mapping Tool
Be prepared for the next flood: sign-up for emergency alerts, make a plan, and know your risk
Impacts to your health can happen during and after a flood. During the flood these impacts include injury and death from hazards like drowning or electrocution. After the flood these risks may be related to cleaning up near or in standing water, lack of access to medical care and medication from power outages and lack of access to safe and healthy housing. You can take some simple steps to prepare for flooding and keep yourself and your family safe.
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Know Your Zone: Learn whether you live in an area where you may need to evacuate the next time there is a hurricane, and learn more about what to do before, during and after a flood at NYC Emergency Management’s flood page and at Rainfall Ready NYC.
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If you live in a basement apartment: Prepare to move to higher ground during periods of heavy rain. Sign up for special basement alerts on Notify NYC.
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Make a meeting plan and prepare emergency supplies. Read comprehensive flood and storm preparation tips. Check on friends, relatives and neighbors. Look out for older adults and people with disabilities, access and functional needs, or health conditions to see if they need help with a plan or supplies.
Preventing future tragedy from flooding means prioritizing housing, infrastructure, and communities
The City’s approach considers present and future flooding risks. The Department of Environmental Protection is improving New York’s drainage systems so that when it rains very hard, the water can drain faster. Additionally, more green infrastructure (absorbent plant or soil systems) is being installed to collect rainfall. This will help keep surrounding areas dry during and after heavy storms. Initiatives like Rainproof NYC will help manage severe rainfall by expanding natural wetlands, which help absorb water.
Resilience to flooding also means access to affordable and safe housing for all New Yorkers. There are programs and resources available for homes impacted by Sandy and Ida.
Resources you can explore to understand more about the City’s climate resilience plans are:
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PlaNYC and Adapt NYC: Comprehensive climate action and adaptation plans.
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FloodHelpNY: Helps to educate New Yorkers about how to protect their homes from flooding.
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Climate strong communities: Conducts local workshops to ensure that community members can guide priorities and learn how to protect themselves and their families.
While severe storms like Ida and Sandy won’t be the last climate disasters we face as a city, by becoming more prepared and informed, along with improvements to our infrastructure and outreach, New Yorkers can stay safe and avoid the health risks of flooding.
To learn more about how flood risk and health impacts are changing in NYC, read the NPCC4 Climate and Health chapter. There are also dedicated chapters in NPCC4 on flooding, climate justice, and more at the New York City Panel on Climate Change website, where you can real the full assessment along with overviews, key messages, and special reports.
JulienneSchaer
Published on:
June 11, 2024