What Kansai airport flooding can teach Hong Kong about the perils of reclamation amid climate change

Martin Williams says the disaster wrought by Typhoon Jebi in Japan should sound a warning to those planning reclamation in East Lantau, who do not account for the rise in sea levels or the increased intensity of typhoons that climate change could bring

PUBLISHED : Friday, 07 September, 2018, 3:01pm
UPDATED : Friday, 07 September, 2018, 5:52pm

Shocking images from Japan have been much in the news of late, including the flooding of Osaka’s Kansai International Airport during the passage of Typhoon Jebi and a ship that had smashed into the bridge serving as the main link to the airport, fracturing a highway lane. The airport was built on an island of reclaimed land.

Less prominent were reports of the airport being evacuated the next day. Some 3,000 passengers and up to 2,000 staff had been trapped there overnight, and most had to be transported by boats, with others carried on buses navigating the bridge lanes that remained undamaged.

According to Japan Today, passengers complained the airport was underprepared for such a disaster. Kansai International Airport, one of the busiest in Asia, had been crippled by the storm, and it could take a week before international flights resume.

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To anyone concerned about Hong Kong’s plans for the East Lantau Metropolis – which should be all of us, given the costs and ramifications – the clobbering of Kansai should give pause for thought as to whether the plans have merit, or are a really bad idea.

If you haven't seen plans for the East Lantau Metropolis, you can find them in a rather jaunty document from the Planning Department and the Development Bureau, titled Preliminary Concepts for the East Lantau Metropolis. This outlines ideas for creating one or two new islands in waters between Lantau and Victoria Harbour, and using these to create a new core business district and housing for up to 700,000 people.

In July, the Our Hong Kong Foundation released an even more grandiose plan, advocating an Enhanced East Lantau Metropolis to accommodate up to 1.1 million people.

Given Hong Kong is prone to typhoons that can bring devastating storm surges, and sea levels are rising with climate change, you might think the potential impacts would be thoroughly discussed in these reports. After all, if a typhoon can cause such havoc on an artificial island with an airport, it’s hard to imagine how severe the effects could be of a major typhoon slamming into an artificial island topped by a metropolis, especially if even a fraction of the million residents require evacuation.

But there has been no such discussion. The “preliminary concepts” document fails to mention typhoons or rising sea levels. The report from Our Hong Kong Foundation has only a superficial consideration of storm surges, suggesting all will be well – in keeping with the rest of the “report”, which is little more than a glossy brochure, citing five supposedly similar projects that are largely just concept plans.

East Lantau Metropolis proposal ignores rising sea levels

Perhaps this seems like nothing to worry about right now, as engineers can surely implement safeguards against storms and rising seas. Yet such measures were implemented at Kansai airport.

This was one of the world’s most expensive civil engineering projects, costing around HK$156 billion (US$20 billion) by 2008 – more than double the estimated price tag, mainly as the airport platform sank far more than expected into the compacting clay below. To guard against typhoon storm surges, the platform was designed to be at least four metres above sea level, and ringed with even higher sea walls.

According to the Kansai Airports website, in 2004, the airport was struck by a number of huge typhoons, with storm surge waves going over the sea walls and washing out roads. Engineers then raised the sea walls, so they could supposedly protect against an abnormally high tidal surge that could occur once every 50 years.

Yet, those walls were breached and, judging from photos, were transformed into impounding walls as the airport platform became like an immense reservoir. That should, in turn, make Hongkongers leery of readily accepting assurances that engineers can solve future potential issues with the East Lantau Metropolis Island.

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It's worth investigating well beyond the facade of glossy brochures, to delve into history and climate science regarding the threats and challenges.

Typhoons may be more intense with climate change, and sea level rise is under way and set to accelerate

First, some history. In most readers’ experience, typhoons are little more than an annoyance, or maybe a chance to have a day off work. Yet Hong Kong and the Pearl River Delta perhaps comprise Asia’s worst-hit area by typhoons and storm surges, with records such as 17,000 square km flooded and 10,000 people killed in 1245; the sea level rising by around 5 metres and 10,000 killed in 1874; and the 1937 typhoon that caused a storm surge and around 11,000 deaths in Hong Kong. Wanda, in 1962, was the last typhoon to hit Hong Kong and bring a major storm surge – raising sea levels in Tolo Harbour by around three metres.

That’s around a metre more than the maximum “wave” anticipated in the Our Hong Kong Foundation report, which blithely bases this notion on an analysis of one, unnamed typhoon. The authors also fail to appreciate that a storm surge is really a local rise in sea level, accompanied by waves whipped by hurricane force winds, like the waves that swamped Kansai airport.

Nor does the report mention that typhoons may be more intense with climate change, and sea level rise is under way and set to accelerate as ice sheets melt at rates higher than many scientific forecasts anticipated. The Hong Kong Observatory projects that, by 2100, the sea level here could be around a metre higher than today. This is in line with typical global estimates, though some forecasts put the rise at double this. And, whichever figure proves correct, the rise will continue, perhaps for centuries.

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So, engineers may be asked to go beyond best-case scenarios and raise the island platform. Doing so would, in turn, add to costs that environment protection groups estimate could be at least HK$500 billion – the foundation’s brochures lack total cost projections – which is “even more expensive than the total sum of the third airport runway, express rail and Hong Kong-Zhuhai-Macau bridge”, according to Tom Yam a member of the Citizen Task Force on Land Resources.

Given that this would be a massive strain on the public purse, it may be worth noting another lesson from Japan – where, as the San Diego Union-Tribune noted, spending on infrastructure, including Kansai International Airport, “yielded painfully little for the rest of the economy”.

Martin Williams is a Hong Kong-based writer specialising in conservation and the environment, with a PhD in physical chemistry from Cambridge University