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Typhoon Mangkhut

Super Typhoon Mangkhut is a flood threat for Hong Kong, but climate change will bring a lot worse

PUBLISHED : Saturday, 15 September, 2018, 7:32am
UPDATED : Saturday, 15 September, 2018, 7:32am

Super Typhoon Mangkhut is forecast to hit Hong Kong on Sunday. Have we learned from the past to minimise the threats?

On August 29, several districts in the New Territories experienced torrential rain and flash floods, even on an amber rainstorm warning. This led to severe flood damage to cars, and electrical equipment and appliances. Firefighters and volunteers had to evacuate animal shelters to save the creatures from drowning.

As a coastal city with a sub-tropical climate, Hong Kong frequently experiences storms and floods. The city receives around 2,400mm of rainfall yearly – 80 per cent during the typhoon season. A large part of the city is also located in low-lying, flood-prone areas.

Thanks to its weather warning system and storm protections, Hong Kong stays reasonably prepared for floods, but recent events such as last year’s Typhoon Hato, which triggered the most severe No 10 signal and caused widespread flooding, showed that these measures may be inadequate.

Climate change will also make flooding more frequent and severe. By 2100, floods that would have occurred once every 50 years will return every three years or less – as a result of rising sea levels and changing rainfall patterns. Many cities around the world have now adopted flood protection standards against once-in-a-century floods; parts of the Netherlands can even withstand once-in-10,000-years floods. Without adequate safety measures, more than 687,000 people and HK$9.3 trillion of assets in Hong Kong are predicted to be at risk.

How Hong Kong is preparing for strongest storm in decades

How much does a typhoon cost?

Flood risk management needs to be anticipatory, rather than reactive. Flood risk profiles should be publicised, so that insurance companies can gauge risk and building developers install appropriate flood-proofing measures.

Aside from improving traditional flood management measures, we need to learn to live with inevitable flooding. Public spaces like playgrounds in the Netherlands double as temporary reservoirs during heavy rainfall. The underground stormwater storage at Happy Valley, for instance, helps prevent drainage systems from being overwhelmed.

Hong Kong residents prepare for the worst

Weather warnings must reflect actual safety conditions. Local warnings like the special announcement on flooding must possess legal validity; they are counterproductive if they do not ensure a state of readiness and let people respond properly.

The cost of playing catch-up on flood protection and remedial works is high, but trivial compared to the potential damages. It is no longer a question of if, but when the next flood will strike.

Wendell Chan, Programme Officer, Friends of the Earth (Hong Kong)