Philip Orton Awarded $215K to Assess Effects of Climate Change on Coastal and Rain Flooding Risk in New York City

Stevens Institute of Technology ocean engineering research associate professor Philip Orton wants to be clear: unlike what doomsaying predictions might suggest, New Yorkers can rest assured that the city as a whole won’t submerge underwater over the course of the next century.

But parts of it will.

“New York City has large swaths that are 50 to 150 feet high, so we're safer than people might think. When you hear New York City is going to be underwater by 2130, it's not true. Nobody's predicting that much sea-level rise in the next century,” Orton explained. “But a part of the city is really at risk, and it could be as much as 10%. That's a lot of people, especially when you have housing problems already.”

A New York City resident himself, Orton was recently awarded $214,717 as part of a $2.5-million study on climate change and its socio-economic impact on the city’s residents.

Titled “Climate Vulnerability, Impact and Adaptation Analysis (VIA),” the 18-month study will develop data and analyze past and present climate conditions around the five boroughs to develop recommendations for future public policy and programs. Key areas of the project include climate and weather projections for the region, including storm surge and extreme heavy rainfall risk analysis and updated coastal flood mapping.

Led by The New School, the project team comprises researchers from nine academic institutions, as well private, governmental and nonprofit organizations.

Stevens will focus on the climate hazard and impact assessment aspects of the project. Orton will concentrate primarily on examining historic climate data and assessing present-day risks of climate change in the city, while postdoctoral researcher Ziyu Chen will focus on rain surge compound flood assessment.

Results of the study will be used in assessment reports by the New York City Panel on Climate Change (of which Orton is a member) and the Mayor’s Office of Climate and Environmental Justice. The results will help inform decision-making on how to support at-risk populations facing issues of social, health and economic vulnerability as a result of extreme weather and climate-change driven events in the region.

“90% of the city isn't at risk, but how do we deal with the 10% of the city that is likely to begin flooding more regularly over the coming century? That's the big challenge,” said Orton. “We're trying to provide information to help people better understand the risks and help make sure that the right decisions are made by the city and the government.”

Climate challenges in the city

Philip Orton; research associate professor; Department of Civil, Environmental and Ocean EngineeringThe hazards of extreme weather and climate change, although placed in especially sharp relief in recent years, have been building in the city for decades, compounded by the realities of the area’s geography, housing and high population density.

While the strength and frequency of major weather events like hurricanes has increased in recent years in general, Orton said, the problem locally is not that storm surges themselves have worsened but rather that the rise in sea level as a result of climate change has made the effect of storm surges on coastal flooding worse.

According to the Mayor’s Office of Climate and Environmental Justice, sea level in New York City has risen 12 inches since 1900 and could additionally increase as much as six feet by 2100. The city notes that some neighborhoods already flood as many as 25 times per year.

The question on the Stevens team’s radar then is not whether the coastal areas of the city will continue to flood but where, by how much and to what extent.

More than a mere nuisance, chronic flooding can result in damage to buildings and infrastructure, personal and business financial loss, homelessness, isolation and diminished access to jobs and necessary resources, widespread ailments such as respiratory diseases due to mold proliferation, and physical dangers including death. Populations most likely to be impacted are those from racially or financially marginalized communities, those with disabilities and older adults.

Climate and weather issues are not isolated to low-lying areas near the waterfront, however. The Climate VIA study also seeks to examine conditions and the detrimental impact heavy rainfall has throughout the city.

Rainfall intensity and extreme rain events have worsened in recent years as a result of climate change, which has led to increased rain flooding. The present-day hazards of such issues, said Orton, has “really opened up everyone’s eyes” to the realities of waters that lie not only around the city but also beneath it.

“There are floodplains that used to be small creeks and river valleys through the city that have been paved over, and when the pipes that are underneath them now get too much rain, they back up, and then you have a river again,” he explained. “There are new floodplains we're becoming aware of that aren't even mapped yet.”

Such heavy rainfalls and floodplain overflows are particularly detrimental to city residents who live in basement apartments. Eleven city residents in basement apartments died in September 2021 when record rainfall caused flash flooding as a result of Hurricane Ida.

A problem of both quality and quantity

One of the difficulties in assessing the probabilities of extreme weather events occurring, which Orton aims to address, is that the quantity of such events is so small compared to the large pool of data on events that are more normal in the region. To be able to address risk posed by events that are so few but so far-reaching in their impact requires a different approach to risk modeling.

While the New York City area averages 10 cool-season storms each year, the more extreme storms — hurricanes — only affect New York City once every decade or two. That vast imbalance of available historical data, Orton said, means data points of more extreme weather can get hidden in the mix.

“There's a danger in assessing risk when you want to look at the chance of having, say, a Category 3 hurricane or another Ida if there's only one or two data points in 100 to 200 years. When we look at all those data points from these cool-season storms, and then have a couple of hurricanes mixed in, we get misled on how likely it is to have a much more extreme storm,” said Orton.

This absence of data quantity means that traditional methods of analyzing historical data only to make projections simply don’t work.

“That's what happened with Hurricane Sandy: the assessments looking at flooding for New York City, including the FEMA flood zones, were too narrowly focused on these milder cool-season storms,” he added. "There wasn't much data in the assessments representing historical hurricanes that are possible for New York City.”

One of Orton’s goals for the Climate VIA research is to develop new processes for assessing the risk of extreme rain events in the area. Part of this novel approach will involve separating out data of extreme events from the more mundane storm events and developing an improved picture of risk by creating a synthetic model of extreme weather based on storms from a larger region of the Atlantic.

Such an approach is used by FEMA for coastal flooding, said Orton, but has never been applied to wind or rain events.

A compound problem

The Climate VIA project will focus on areas around the city, including oft-neglected geographic areas in the Bronx and northern Queens.

“One thing that we’re doing that hasn't been done before is we're contrasting what we see for the water levels in New York Harbor and how they correlate with the rain happening around the city and also in Long Island Sound, the Upper East River between Bronx and Queens, near LaGuardia Airport, and even further out — which is a different tidal water basin and has much bigger tides and different storm surge,” Orton said.

The Stevens team is particularly interested in conditions where multiple sources of flooding occur simultaneously and intensify the impact of each other, a phenomenon known as compound flooding.

“In a coastal floodplain there can be flooding just from the rain when the sea level’s already high and the sewer pipes won't drain, for example,” Orton explained. “For the VIA project, we're working on understanding the chances of how coincident rain and storm surge, or storm surge and tide, lead into worse flooding.”

Such compounded conditions, Orton said, have not been sufficiently studied or considered in the past ­— or necessarily in the present, for that matter. Too often, he said, studies take into consideration only one flooding phenomenon at a time. As a result, much flood zone mapping remains insufficient and meteorological forecasts often fail to sufficiently convey the possible dangers when multiple types of flooding combine.

Studying such combined phenomena, in contrast, is a major focus of Orton’s research.

In a separate study being conducted in New York City’s Jamaica Bay area, Orton and Department of Civil, Environmental and Ocean Engineering assistant professor Kaijian Liu are developing hydrodynamic and machine learning models of coastal flood risk that incorporate both the impact of rainfall and storm surge in their analysis. The project is sponsored by the U.S. Geological Survey and is in collaboration with Brooklyn College and Columbia University.

Orton hopes that the results from each project can themselves compound for greater impact.

“The statistical analysis being done under Climate VIA can be complementary to the observations and machine-learning modeling that we're doing for that USGS-funded Jamaica Bay project,” Orton said. “My hope for the VIA project is it can inform the Jamaica Bay project.”

Since Orton joined Stevens in 2010, he has conducted oceanography and meteorology research in the New York metropolitan area in large part thanks to grant funding through the Consortium for Climate Risk in the Urban Northeast, a National Oceanic and Atmospheric Administration-funded project that examines climate vulnerabilities in urban areas along the Philadelphia-New York-Boston corridor.

Although more insulated from certain kinds of climate hazards compared to other parts of the U.S. (such as extreme hurricanes, wildfires and drought), climate change-driven conditions in the New York City area, Orton ultimately concluded, are a mixed bag.

“There's little bits of, It's not as bad as you think, and there's little bits of, It is as bad as you think,” he said.