Lately, our headlines have been inundated with flooding news. Severe flooding in Bangladesh, Nepal, and India, Hurricane Harvey’s destruction at an unprecedented scale, and Hurricane Irma already stated as “one of the most powerful storms ever recorded” with potential for catastrophic flooding. Floods are currently the most common extreme weather event, and with climate change this is only expected to increase.  Flooding can particularly wreak havoc in cities, as exemplified by Hurricane Harvey which left Houston underwater. Yet here at Sustainia we know that within each risk there are opportunities. Let’s take a closer look at what cities can do to prepare for storm surges.

Infrastructure adaptation is a cost-effective opportunity for cities to protect themselves from the devastating impacts of extreme weather events, while also making them more pleasant and healthy places to live everyday. With an estimated $180 billion  in damages, Harvey truly revealed the inadequacy of century-old infrastructure. Even though the hurricane was unprecedented in scale, the extent of the damages was also a result of urban planning, or lack thereof. Houston was hit hard for a reason. The city has been rapidly urbanizing for years, sprawling out over a large area, and urbanization calls for concrete – and lots of it. Concrete prevents stormwater from being absorbed into the ground, and this accelerates flooding and overwhelms drainage systems.

To prevent damages on the scale of Houston, we need to integrate into our city planning the understanding that preventative flood management is worth the money in the long run. According to the National Institute of Building Sciences in the United States, for every $1 spent on hazard mitigation, it results in a  $4 return of future benefits. It is cheaper to invest in infrastructure that makes cities more adaptive to climate change now, than it is to wait until it’s too late. We estimate that if cities do not invest significant amounts into resiliency, cities worldwide can expect an annual cost of $314 Billion as a result of natural disasters.

An example of flood-preventing infrastructure are naturalized areas, also known as “ecological infrastructure”. These include wetlands, trees and urban parks, which work to absorb flood waters and therefore reduce the impact of flooding events, while also providing a plethora of other benefits. Not only do naturalized areas make cities more adapted to climate change, they also make cities more enjoyable and attractive places to live, reduce public health expenses by proving cleaner air and places for recreation, and even reduce energy costs by cooling cities.

What are some inspirational examples that we can see from cities taking a lead in flood prevention today? Here are three innovative solutions from the Cities100 reports. Each of the Cities100 reports showcase 100 of the leading solutions to climate change from cities around the world. These outstanding examples have integrated green infrastructure in their city planning to create cities that are more resilient to flooding, and better places to live.

Stormwater Management Prevents Flooding in Hong Kong

Hong Kong already has one of the highest rates of rainfall in the Pacific Rim, and storms are only expected to become increasingly common. The city needed to create an approach to flood management that allows them to maintain their economic growth without sacrificing sustainability or safety. The solution was to take a city wide, proactive approach by intercepting waterways along their natural courses. Hong Kong built a network of stormwater drains, river channels, and storage tanks. Not only do these systems prevent flooding, but they have improved the natural environment of the city and it’s surrounding areas, and have created 144km of revitalized waterways where residents are provided enjoyable places to walk and cycle. These areas have improved opportunities for residents to enjoy more urban outdoor activities, while property values have risen by up to 10% in areas that have experienced the water revitalization.

Cooperation Strengthens Coastal Stormwater Protection in New Orleans

The City of New Orleans, with Hurricane Katrina still in recent memory, is working to protect itself from rising sea levels, frequent flooding, and an increase of storms. The city has developed what they call  the “Urban Delta initiative,” which increased cooperation between areas of government, to create a more cohesive approach and identify gaps in storm protection. One of their pilot project is the NORA rain garden, which can collect, clean, and temporarily store rainwater while it gradually flows into the city’s drainage system, therefore decreasing flooding risk.

Climate-Resilient Neighbourhood in Copenhagen

In 2011, a single cloudburst caused over $1 billion in damage in Copenhagen from a sudden burst of heavy rainfall. After this event, Copenhagen knew the city needed to take action to prepare itself for the future. The result was the first climate resilient district in the world – Østerbro Climate Quarter. Østerbro uses an integrated system of rooftop rainwater diversion, forested streets, pocket parks, and natural landscapes to retain and funnel water. In total, 30% of the rainwater will be diverted from the sewer system. This concept was actually cheaper to implement and maintain than expanding sewers, and reduces the financial impact of future extreme weather events. Not only that, but it has provided a social benefit by involving 10,000 people in citizen lead volunteer initiatives, and will improve air quality, biodiversity, sequester carbon dioxide, and not to mention provide a more pleasant neighborhood to live in.

These solutions are on a city wide scale, but can we do as citizens? We can plant more trees, shrubs, and grasses in our backyards. We can reduce the amount of concrete and impermeable surfaces on our properties, by using new technologies such as permeable pavement. We can also use low tech but effective solutions such as replacing concrete with gravel or rocks for better drainage, diverting rain spouts, and using heavier mulch.  If we take action as citizens on what we can control, and become involved in our local government to push for more climate resilient cities, in the future we can help prevent the extent of the damage from powerful storms such as Hurricane Harvey. We know there will be more storms, let’s make sure we’re ready for them.

Author: Michelle Gordon