Timon McPhearson, Director of the Urban Systems Lab, Discusses Urban Resiliency Efforts to Manage Extreme Weather
The torrential rain from the recent storm Hurricane Ida and subsequent flooding laid bare the need for cities to invest in resiliency from the increased frequency of major storms. Timon McPhearson, Professor of Urban Ecology & Director of the Urban Systems Lab at The New School, discussed the effects of extreme weather on New York City and what may be done to mitigate the damage from storms like Hurricane Ida.
Why has flooding become worse in New York City?
Flooding from coastal storms and extreme rainfall is not new in New York City. There have been many flood events in the past. However, climate change is increasing the frequency and intensity of storms in the region and projections from the New York City Panel on Climate Change suggest the city will face high variability in rainfall in the coming years. We are likely to face more extreme rainfall and flooding (and even more droughts). Our position in the North Atlantic also means the sea level is rising faster here than other parts of the world, and so tidal flooding will be an increasing challenge.
However, it’s not just climate change and extreme weather that create conditions for flooding. The way we have built, designed, and developed the city has largely paved over nature and the ecological infrastructure of the city making many areas impervious, forcing water to flow along the surface on streets, sidewalks downhill into basements, subways, and other low lying areas. Making the city more “pervious” so that it can absorb more water, like through the 10,000 green infrastructure installations the city has already made, will require a very different development agenda that puts stormwater absorption as a central priority. This is essentially a massive retrofit of our existing urban infrastructure.
What are some of the immediate challenges to addressing this problem?
Our immediate challenges are improving our emergency response, helping New Yorkers who are most vulnerable or live in high flood risk areas to be able to evacuate to safety or have a plan and resources in place to avoid the worst impacts of flooding. This also means ensuring that we have enough pre-storm warning so that the city and all residents can be ready when the storm hits.
The city released a significant report on combatting storm-related extreme weather in NYC last week that outlines a number of immediate challenges and I would encourage everyone to read it. The report prioritizes upgrading storm modeling, tracking, and alert systems, educates us all to the new reality of extreme flooding, prioritizes investments in low income, immigrant communities, and communities of color, and focuses on protecting those living in basements and cellars. All of these efforts will take time and major financial investments but are critical to avoid the worst impacts.
What are some of the long-term issues?
Over the longer term we may face even more severe storms. There is real concern that eventually we’ll live through a storm that combines the coastal storm surge of Hurricane Sandy with the extreme rainfall of Ida. Building community, infrastructure, and ecological resilience to flooding from both extreme and chronic flooding means investing in all three areas simultaneously and will ultimately require federal support beyond what the city is able to provide. The impacts of flooding are not felt equally and so prioritizing flood resiliency investments in the communities that need it most is paramount.
The one million buildings in the city will need to manage more of their own stormwater so that run-off is locally captured, stored, and released slowly and safely into the drainage system. We will also need to create pathways by raising curb heights and installing other flood conveyance for water to move safely along city streets and natural drainage areas without flooding homes, businesses, power stations and other critical infrastructure.
The Urban Systems Lab has been part of a team of researchers in NYC studying urban and compound flood risks associated with current and future extreme rain events. What have been some of the results of that work for the city?
Our work in the Urban Systems Lab (USL) has supported city resiliency efforts for many years. We co-lead the NYC Stormwater Resiliency Study from 2018-2020 with our partners at CUNY, Stevens Institute and others, which developed the first phase of the future flood scenarios models released earlier this year. We provided a comprehensive technical report to the city which underpinned many components of the NYC Stormwater Resiliency Plan. We also developed a data visualization decision support tool, https://stormwater.nyc/, so that anyone can examine potential flooding in their neighborhood and examine whether local populations or critical infrastructure may be at risk.
What is clear from USL work is that there is likely to be extensive flooding in many parts of the city from both future extreme rainfall or compound rain and coastal surge. When you overlay future flood scenario maps with low-income communities and communities of color you see some not surprising but still worrisome hotspots that will likely have disproportionate impacts on these communities. We also find that some locations of critical infrastructure that provide essential services such as hospitals, fire stations, or homes for the elderly are in, or very close to, locations likely to flood. This means that over the longer term we not only have to better protect these places as well as at risk residencies but may even need to move them to locations on higher ground.