Niklas Ohlrogge
It’s no secret that as the climate changes, it will significantly alter the living conditions of city dwellers around the world. Changes in weather patterns wrought by climate change will mean less precipitation in some regions, while an increase in other regions will result in severe flooding. In July 2021, record high rainfall events caused floods which resulted in the deaths of hundreds of people and the destruction of multiple villages and towns in Germany, Belgium, and the Netherlands. Last September, in the span of less than a day, the remnants of Hurricane Ida dumped over 17 centimeters of rain in New York City. Subway stations and the basement apartments of New Yorkers residing in low-lying areas were flooded, and around 40 people in the metropolitan area died.
Along with an increased occurrence of extreme rainstorms, climate change is also causing sea levels to rise. This means that many coastal regions will be permanently submerged and rendered uninhabitable and that the severity of flooding events will be exacerbated as bodies of water will have less capacity to absorb excess rainfall. Tropical cyclones, like Hurricane Ida, will also become more common due to climate change, which also means an increased occurrence of flooding from storm surges and extreme rainfall.
But while the negative effects of climate change are clear, cities under the greatest threat continue to grow and develop. More significantly, they continue to develop in the areas at the highest risk of inundation by water. Nine Elms, a London neighborhood situated on the Thames, is experiencing nothing short of a wholesale redevelopment, with the construction of over twenty new high-rise residential and commercial buildings in the area. The waterfronts of Brooklyn, Manhattan, Queens, and The Bronx host some of the newest, largest, and most capital-intensive real estate developments in New York City. Even in Amsterdam, the most recent real estate development is concentrated on waterfront sites, such as in IJburg and Overhoeks.
Granted, part of this trend is a result of the availability of land, and waterfronts are among the last areas in many cities that have yet to be re-developed. Until the late 20th Century, waterfronts, especially those in Western Europe and the United States, were used primarily for heavy (and often heavily polluting) industrial uses, and for the transport of goods. After Western cities deindustrialized and ports required less space and different types of facilities because of containerization, waterfronts were more or less abandoned. Grain terminals and lumber yards sat empty with low demand for their services. With locations on picturesque bodies of water, waterfronts were then ‘rediscovered’ by developers as promising sites for new real estate development. Their state of relative neglect also meant that they were often inexpensive to acquire.
Considering the value this type of development can generate, the trend of waterfront development will likely continue, despite the threat of climate change-induced flooding from increased rainfall, storm surges, or sea-level rise. Driven by short-term profit and often by incentives and zoning deregulation along waterfronts implemented by public authorities, private developers will continue to construct new residential and commercial buildings along waterfronts. And motivated to boost (affordable) housing production, the public authorities of the many cities with housing shortages will continue to incentivize and even cooperate in the development of new housing along the waterfronts, as observed in New York, London, and Amsterdam as well.
Granted, waterfront development has its virtues, but the increased peril in which riparian and littoral cities are being put means that this trend must be reconsidered. A total cessation of waterfront development would be the most optimal, to prevent any damage caused by extreme weather. However, this would not be easy to enforce, and, in the case of low-lying countries like the Netherlands and Bangladesh, it would be unrealistic.
In the spirit of being pragmatic when resolving this issue and reconciling waterfront development with an increased risk of storm surge and rainfall flooding, cities should ensure that new neighborhoods next to bodies of water are resilient. Cities should stipulate that buildings constructed in these areas are able to withstand floods, which means that their utilities are able to continue functioning or at least survive without serious damage. This might mean ensuring buildings in flood zones have generators or batteries so that servicing of electric power needed for lighting, electric appliances, and the pumping of water is not disrupted. Cities have introduced rules for these relatively simple adjustments.
On a neighborhood scale, there are multiple ways to protect residents and minimize damage from floods. In New York City, for example, a new mixed-use development in the neighborhood of Edgemere, which sits near the Atlantic Ocean on the Rockaway barrier peninsula, is incorporating numerous design elements to meet those exact goals. This development, called Averne East, will consist mostly of new, affordable housing units but also a hotel, new commercial and office space, and a brewery. Already impressive for its expected net-zero carbon emissions status, L+M Development Partners, the developers behind the project, and Local Office Landscape & Urban Designers, a firm involved in its design, have also included numerous design elements that will make the development more resilient. Heeding the call from experts and advocates to center resiliency in new developments, the new district will include bioswales, rain gardens, porous pavement and asphalt, and roofs capable of catching and retaining water in cisterns. All of these features will increase the permeability of the surfaces in the neighborhood and their capacity to store excess rainwater and reduce flooding. Additionally, given the sandy soil upon which the beachfront property is located, the percolation of fresh water will maintain the fresh-saltwater divide in the water table of the peninsula.
In addition to protecting against flooding caused by precipitation, the entire new district will be slightly elevated, and all apartments and mechanical equipment built on the site will be 4.8 meters above the ground level, assuring a storm surge will not directly damage anyone’s home or utilities. As another means of storm surge protection, part of the site acquired for this development will be reserved for the development of natural dunes, which will attenuate the waves from a storm surge. Additionally, the boardwalk separating the development from the beach was rebuilt to provide protection from flooding caused by storm surges exceeding three meters in height.
HafenCity, in Hamburg, offers an excellent example of how larger riparian neighborhoods can be planned to be resilient against the dangers of living next to bodies of water. A quintessential example of a waterfront area formerly dominated by sites used for commercial, bulk shipping, HafenCity is a mixed-use neighborhood on artificial islands built on the northern banks of the Elbe River in the center of Hamburg. Recognizing the risk that this area and the rest of Hamburg face from climate change-induced sea level rise and extreme weather, its developers and the city raised the elevation of the islands. The city also stipulated that the buildings in HafenCity have elevated walkways and entrances on the first floor to allow for safe passage when the Elbe River bursts its banks.
Edgemere and HafenCity both demonstrate that living next to water is possible and that retreating from the coasts, which is not entirely feasible, is unnecessary if cities adapt to the new reality properly. The adaptations made by these developments also demonstrate that ‘hard’ infrastructure, such as dike systems and water pumping stations, to protect against flooding, may not be necessary either. In cities where space is in short supply, this type of infrastructure is inefficient, and it can disrupt pedestrian connections between people and the water. While climate change might make living near water more perilous, the problem is not the water itself, but the way we live around it. Planning our cities accordingly can mitigate the danger and make waterside living a safer, more sustainable endeavor.