Over the past month, news of the torrential downpour that drenched California has poured in. There were difficult circumstances for Californians to deal with, and at least 22 people died.
A student scientist estimated that over 30 trillion gallons of water are totaled throughout the state. However, most of that water ran back out to sea in a state that was experiencing an unrelenting drought.
When 150mm, or about 6 inches, of rain dropped in only two hours in Copenhagen, Denmark, in 2011, it was the heaviest rain to fall in a 24-hour period in more than 55 years, but it was a brief downpour.
The city started to develop a plan to manage the water from these types of short-burst intense rainfalls that are predicted to be more common occurrences not just in Copenhagen but across the globe as a result of the climate crisis, along with a study from 2021 noting that a significant increase in intense, slow-moving storms would happen in the future in Denmark and across Europe.
The outcome was the Cloudburst Masterplan, a multi-municipality strategy that will assist Copenhagen to manage the negative consequences of heavy rain.
According to Martin Zoffmann, Ramboll Water’s communication manager, the company that is assisting in the planning and implementation of the master plan, there are a total of more than 250 larger-scale projects spread out around the city.
The projects are connected in branches, and because of their multipurpose and environmentally friendly design, it offers protection and improves livability throughout the city.
As an illustration, consider Copenhagen’s St. Annae Square. Previously a field that was prone to flooding, this area has been modified so that the rainwater now empties into the port.
This has not only prevented the water from harming nearby buildings and accumulating in the main square where people congregate. New storm pipes and gutters were constructed, the area was reconfigured to resemble a bowl, and the surplus water now drains to the port.
In its designs, Ramboll employs so-called blue-green infrastructure. Blue-green infrastructure, or planning that takes into account both water and land, can be characterized as hydrological functions with urban nature, landscaping, and urban design.
And other cities at risk of flooding are taking notice. Another illustration? The NYC Department of Environmental Protection became interested in the Copenhagen Masterplan (DEP).
Even though Hurricane Sandy was a once-in-a-lifetime occurrence, it revealed how badly New York City managed water, especially during periods of heavy rain. The DEP made five trips to Denmark to investigate the project after learning about the Masterplan.
The two cities inked a cooperation agreement in 2015 with the goal of enhancing climate resilience in each city through knowledge and technical information exchange.
The need for some sort of heavy rain mitigation scheme became even more pressing in 2021 when Hurricane Ida slammed the New York region, dropping 10 inches of rain in just three hours—the precise definition of a cloudburst.
The city of Copenhagen’s attempts to integrate climate adaptation with urban redevelopment work most impressed Alan Cohn, executive director of Integrated Water Management at the NYC DEP, on a visit in 2022.
In order to revive open space in communities, this entails combining various types of knowledge and resources and including cloudburst management into the procedure.
What ultimately resulted from this? Mayor of New York City Eric Adams announced a $400 million extension of the Cloudburst project in January of this year. It will focus on four flood-prone areas of the city:
East New York, Parkchester, Queens’ Corona and Kissena Park, and the Bronx’s Parkchester. In order to absorb, store, and move extra stormwater, grey and green infrastructure—which combines natural areas with pipelines, reservoirs, and treatment facilities—will be incorporated into the infrastructure projects.
In order to protect New Yorkers from heavy rains and make our city greener, expanding our cloudburst programs is essential, according to Mayor’s Office of Climate and Environmental Justice Executive Director Kizzy Charles-Guzman.
Environmental justice communities urgently require green infrastructure initiatives, and the suggested solutions will increase and enhance access for bikers and pedestrians.
In Southeast Queens, two Cloudburst pilot projects are already active in New York. These initiatives support sewer and green infrastructure initiatives. A visualization of this Cloudburst installation in a sizable NYCHA courtyard was published in the NYC Green Infrastructure 2020 Annual Report:
This strategy and how the New York City Housing Authority has been driving the charge in cloudburst management projects are covered in full in an article published on Grist in October last year.
As a result of this special collaboration between Copenhagen and New York City, projects to build climate resilience have been implemented in both cities and shared knowledge has been generated. The Copenhagen-based corporation Ramboll is collaborating with Miami, Singapore, and other cities to help mitigate flood damage.
While managing large bursts of water continues to be a priority, it is all a part of water management, and perhaps one day California, with its incredibly intricate water management systems, will be able to find a way to hold onto some of the water that is being lost back to the ocean while also lessening the devastation of flooding brought on by large amounts of liquid.