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Typhoon Mangkhut

Typhoon Mangkhut, like Jebi, showed why East Lantau reclamation is the wrong option for Hong Kong housing

PUBLISHED : Monday, 24 September, 2018, 5:03am
UPDATED : Monday, 24 September, 2018, 5:03am

I recently wrote in these pages about how the disaster wrought by Typhoon Jebi in Japan should be a warning to those planning reclamation in East Lantau, who do not account for the rising sea levels or stronger typhoons that climate change could bring (“What Kansai airport flooding can teach Hong Kong about the perils of reclamation amid climate change”, September 7).

Perhaps this seemed far-fetched at the time, given the rarity of typhoons with storm surges in Hong Kong in recent decades. Yet, Typhoon Mangkhut on September 16 brought a record-breaking storm surge, along with waves whipped by ferocious winds. The videos of waves pounding Shek O, Sai Kung, Tseung Kwan O, Heng Fa Chuen and other places showed what “storm surge” really means and – like Typhoon Jebi – showed that it is a threat to modern cities, not just something from the history books.

The surge of 2.35 metres at Quarry Bay was higher than the two metres planned for in Our Hong Kong Foundation’s proposal for an Enhanced East Lantau Metropolis, and made higher still by Mangkhut’s big waves. This clearly demonstrated how storm surges could threaten a metropolis built on an artificial island.

Climate change will make cost of artificial island rise, experts warn

It is surely tempting to respond that surges are rare, or that engineering solutions like a higher island platform can act as a safeguard. Yet, a Hong Kong Observatory account of Typhoon Wanda, which caused a major storm surge in 1962, notes that“destructive tidal surges were reported in Tolo Harbour in 1874, 1906, 1923 and 1937”. And this, along with other historical records, suggests that storm surges are not really uncommon here, just unusually scarce recently.

Further, in some ways Hong Kong was lucky with Typhoon Mangkhut, which lost some strength as it crossed Luzon in the Philippines, and passed 100km to the south during daytime, when the forecast tide was a metre lower than at night. This means even more intense storms are possible; and as sea levels rise, storm surges will be a greater threat.

Reclamation for East Lantau Metropolis would be a costly mistake

Planners fixated on the East Lantau Metropolis ideas may call for engineering solutions like building the island platform even higher – rather as Kansai Airport’s defensive wall was raised, ineffectually as it turned out. But surely the best option is to build elsewhere, such as on brownfield sites, even though there are some challenges.

Dr Martin Williams, founder, Hong Kong Outdoors