New storm defences for Hong Kong after experience of Typhoon Mangkhut – and as climate change threatens even worse
- Government identifies areas in need of special protection from floods
- Intends to roll out new preparations for typhoon strikes, and floating breakwaters to lessen waves’ impact
Hong Kong will introduce a new storm defence system to fend off extreme weather after Typhoon Mangkhut wreaked havoc around the city last year.
A new wave warning system and floating breakwaters will be tested in the coming storm season – starting in May – in areas susceptible to flooding and high waves, the Drainage Services Department said on Thursday.
“Climate change has gained recognition in international society,” department director Kelvin Lo Kwok-wah told reporters.
“Adverse weather may come more often and in more strength.”
The department identified three coastal spots most exposed to high waves, including southern Tseung Kwan O, Heng Fa Chuen on the east of Hong Kong Island, and South Horizons in Ap Lei Chau.
The three places – dubbed “overtopping wave spots” – suffered severe damage during Mangkhut, which hit in September 2018. In Heng Fa Chuen, for example, the strong typhoon damaged lifts, ripped out windows, and led to the loss of fresh water supplies.
Another seven coastal locations that flood badly during typhoons were also identified. These so-called storm surge spots are all below sea level, including places such as Lei Yue Mun, Tai O and Nam Wai in Sai Kung.
Lo said the department, in collaboration with the Observatory, would introduce a storm warning system for the seven storm surge spots and Heng Fa Chuen in the coming typhoon season.
Under the system, the Observatory will issue warnings 24 hours in advance if water levels in those areas are predicted to reach a certain point – 3.5 metres for Heng Fa Chuen, for example. The department will then send emergency teams to the areas to help prepare for defending against waves and flooding.
In the case of housing estates like Heng Fa Chuen, the department would also inform the estate management about the warning and offer advice on preparations.
For the other two overtopping wave spots, the department was still studying storm surge models, so the system may not cover the two locations this year, according to Edwin Lau Shing-cheong, chief engineer of the department’s land drainage division.
The department is also in the process of buying a batch of floating breakwaters that can be anchored in the sea to absorb waves before they hit permanent breakwaters, Lo said.
He said some brands of breakwater could reduce waves from 3.5 metres to 2.8 metres.
Lo added that the floating breakwaters, which had never been used in Hong Kong before, would be tested at the Ap Lei Chau Sewage Treatment Plant this year. If the test yielded positive results, the department might use the new equipment in other areas such as the three overtopping wave spots, he said.
Stanley Ho Ngai-kam, who represents Heng Fa Chuen on Eastern District Council, said he appreciated the government’s efforts to reduce the impact of waves on coastal areas, and that he believed the warning system could help.
But he said the floating breakwaters should also be tested at Heng Fa Chuen this year.
“We all know Heng Fa Chuen is one of the areas that suffered the most last year,” Ho said. “If the floating breakwaters can be tested at Ap Lei Chau, why can’t they be tested at Heng Fa Chuen too? Anything that can help the estate defend against waves should be tried here.”
He said he would speak to the department about testing the breakwaters in the area.
