Smart Design for Rain

The 1st of September 2021 marked the beginning of a new era for New Yorkers. Heavy rain inundated communities throughout the five boroughs, causing massive flooding in places that have never flooded before. In subway stations, rain turned staircases into waterfalls, basements and ground floor apartments flooded, and cars, bikes, and pedestrians were stuck in floodwaters. Within a single hour, 3.15 inches of rain fell, breaking Hurricane Henri’s record ten days earlier.

The water seemingly disappeared 24 hours later, but the psychological imprint of the storm lives on. Approximately $16 – $24 billion in damage was caused by the flooding in the Northeast, and over 188,000 tons of debris were left behind. The most shocking impact was the 43 people who drowned – 11 in their own homes, trapped by flood waters in basement apartments. It was simply impossible for New York City to handle the intensity and duration of the rain.

However, with smart design, the concrete jungle can be turned into a sponge. The city’s 100 year old sewer system may not be equipped to transport the rain by itself, but the city can find ways to store and transport water at a manageable pace.

Blue and green roofs are impeccable solutions for high rise buildings to slow down the water flow. Blue roofs collect a layer of rain water, which is released at a controlled pace through valves down the side of the building, buying the sewers valuable drainage time. Green roofs are covered with a layer of vegetation and soil that not only provide a rainwater buffer, but also reduce heat, improve the air quality, and lengthen the lifespan of the roof. Even a building without a blue or green roof can contribute by constructing water retention tanks in the basement to store runoff.

When it comes to designing for rain, permeability is key. In a city covered in concrete, permeable pavement is an excellent option for allowing rainwater to filter at a steady pace. The top choice for permeability however will always be green space. Bioretention strips provide attractive greenery that temporarily holds water, and then filters it through a gravel zone layered beneath the foliage. Parking lots that are paved with permeable concrete and lined with bioretention strips turn a runoff nightmare into a powerful contributing factor.

With another hurricane season fast approaching, the city must prepare for potential floods. At BEAM Architects we believe that intelligent design is beneficial to all, and by enacting it whenever possible, we can help our resilient city grow even stronger.

– Kuba Jastrzebski