Earth Matters: Asphalt sets stage for flash floods

The Island Now
Dr. Hildur Palsdottir

By Hildur Palsdottir

In a warming climate the atmosphere holds more moisture from evaporation, which in turn leads to more extreme and unpredictable weather events. When it rains, it often pours, resulting in unexpected flash floods.

We must support mechanisms that clean the air of carbon and cool the planet (hint: photosynthesis), as we’ve reached a tipping point already. The most recent United Nation report warns that we can expect a cascade of changes that at best leave us with 2.7 degree Celsius warming of average temperatures by the end of the century, even if today’s most ambitious climate goals in terms of reducing emissions are met. This means even worse wildfires where there is drought and more frequent flash floods elsewhere.

Lower-income regions have typically been most affected by extreme weather events, while also least likely to contribute significantly to the greenhouse gas emissions that drive climate change. The climate narrative is now shifting to include the wealthy; this summer major emitters faced devastating losses and in one of Northern Europe’s deadliest floods over 240 lives were lost.

Billion-dollar disasters are the new norm in the “overdeveloped” world. Our concrete infrastructures aren’t designed for this “new meteorological era.” Climate has changed, but we haven’t.

Dramatic headlines did not seem to affect daily lives in New York suburbs too much until the aftermath of Hurricane Ida killed our neighbors. New York’s Central Park measured a record-breaking 3.15 inches of rain in one hour. Rushing through subway tunnels and sewage pipes, in just a few hours this record rainfall took at least 50 innocent lives in the Northeast. In unsafe basements in Queens, unimaginable tragedies took place, where 19-month-old Lobsang Lama was the youngest victim to drown.

Looking at maps of Woodside and Flushing from the early 20th century, it’s evident that the ecological function of the worst affected area included a pond and watershed. Where 153rd Street is now, a pond was landfilled with materials from the construction of the Long Island Expressway and little thought was given to accommodating for waterways. Every house on that street flooded.

Historically, we like to build where it’s flat or near water and about 87 percent of our world’s wetlands are degraded from human activity. We’ve replaced natural surfaces with asphalt. Instead of salt marshes and freshwater wetlands that absorb and retain water, we have paved over with concrete.

Certain surfaces are more likely to feature flash floods. Crew cut chemical lawns are second to cement in sealing the ground. Short rooted grass on compact, mostly abiotic ground robbed of its nutrients doesn’t feed the microbes and the earth worms that help aerate and make healthy soil porous. In contrast, rewilded, deep-rooted native plants and woodlands naturally help intercept and drain intense rainfall while recharging the aquifers.

It is time we restored ecological sanity and committed to climate resiliency by improving green infrastructure and regenerating our estuaries and wetlands. It is common colonial practice to completely disregard pre-existing ecosystems, and instead landfill and build concrete housing projects, even basements, in flood plains. We re-route water, seal natural surfaces with cement and continue building until there’s very little left of spaces for water to flow.

On Long Island, we have sealed the surface with sidewalks, roads, parking lots and strip malls, with large areas prone to flash flooding. Excessive urban development in flood plains without natural surfaces for ecosystem services leaves us exposed to the elements and at risk. The physical damage to infrastructure and buildings from what was left of Ida exceeds $50 billion in the greater New York area. It only makes sense to invest upfront in natural climate solutions that will lessen the cost of future disasters.

Intelligent design for stormwater management includes carving out bioswales and planting rain gardens. A swale is designed to slow the flow of water, so that it is collected and gradually infiltrates the landscape. We used to build ditches to divert water, drain or carry it away, but we must change that attitude and instead repair the relationship to water by allowing the ground to receive it again.

At the Science Museum of Long Island, Plandome, a sizable grant from The National Fish and Wildlife Foundation’s Long Island Sound Future Fund is invested in planting demonstration gardens of that function, so stay tuned for upcoming classes. You can be part of the solution and welcome water where you live.

Urban development can’t remain oblivious to basic ecology and hydrologic function. To confidently adjust to a rapidly changing climate, we must insist on ecoliteracy at all levels of government. We must ban basement dwellings in flood plains, stop concrete development at the cost of waterways and support safe housing projects on stable grounds.

Climate has changed, so must we. We must adapt to the changes and prevent an ecological collapse by strengthening our natural defenses. For citizen-driven action, join Transition Town Port Washington ( and learn how to contribute to local and natural climate solutions.

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