13 September, 2018
The force and frequency of typhoons is increasing across the world, and we see this happening in Asia too. Japan, a country that has undergone a series of natural disasters this season, saw Typhoon Jebi, the latest and the country’s strongest typhoon in 25 years, paralyzing major cities in the west cost of Japan. In China, Typhoon Rumbia, the 18th typhoon this year, battered east China's Zhejiang Province in August, affecting nearly 9.5 million people and damaging the country’s biggest produce supplier. Hong Kong, hit hard last year when Typhoon Hato caused HKD$8 billion in losses, has also experienced a few smaller typhoons this season, and is expecting Super Typhoon Mangkhut to make its way towards South China Sea in the next few days.
Violent rain and flooding
The increased intensity of the typhoons can be attributed to climate change1). Particularly urban regions with a large population in a condensed area, such as Hong Kong, are at risk of paying the toll in terms of both material damage and casualties or deaths. Flooding from storm surges will be magnified, with heavy downpours sweeping the streets.
Cities that work as a sponge
We need to be better prepared and protect our cities against the impacts of intensified natural disasters. One way of achieving this is the “sponge city” concept. This is a sustainable drainage system that absorbs, captures, controls, and purifies water in its direct vicinity – managing excess rainfall and integrating it into the urban design.
Reducing the damage
Since 2016, Arcadis has been the principal consultant of the Wuhan, China’s sponge city pilot project, which reduces economic and environmental damage caused by pluvial flooding. Sponge cities work with infrastructure such as green belts and roofs, wetlands, rain gardens, filtration pools, retention ponds, and permeable pavements, and integrate it with other flooding controls. This enables urban landscapes to absorb storm water, ensuring water works for the city rather than against it.
Sustainable drainage of storm water
Another measure to build up water resiliency is the use of Sustainable Drainage Systems (SuDS). A SuDs utilizes techniques such as bio retention systems, green roofs and porous pavements, to drain storm water in a more sustainable fashion than conventional grey infrastructure solutions. This feature will be particularly useful during heavy rain, when a city receives a significant amount of rainfall within a relatively short period. Shifting from a grey to a green solution like SuDS will see rainwater absorbed, filtered and returned to the source.
Public and private funding
Developing a large-scale and long-lasting infrastructure requires a tremendous injection of cash. So where will this money come from? A Public Private Partnership (PPP) model has proven to be effective in many world cities. The effects of climate change are imminent, as we have witnessed and experienced globally and locally. It is time to become more proactive in future proofing our cities, it will pay-off in more than one way.
A strategic water resilient approach, including the application of technologies such as sponge cities and SuDs, will safeguard our cities from risks and help ensure their recovery when disaster strikes. The ability to withstand stresses and to rebound quickly and successfully from shocks is essential for a city to remain competitive, investable and livable. The resiliency dividend will certainly be worth it in the short and long-term.
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