As the public consultation period for the Kau Yi Chau Artificial Island project is set to close by the end of this month, former Hong Kong Observatory director Lam Chiu-ying said authorities have yet to account for the risk of the entire project being submerged underwater.

Lam said the government's plan of setting up a buffer zone could only handle seawater brought onshore by huge waves and is unable to handle the issue of rising sea levels, which would persist for the following 200 to 300 years and even up to 1000 years.

He said authorities have to constantly increase the height of the seawall to offset the rise in sea level; he also cast doubt on whether authorities have taken into account the additional cost of such infrastructure work.

Meanwhile, the weatherman also questioned the effectiveness of authorities’ proposal of building Y-shaped water channels to alleviate the heat island effect, adding that there needs to be an endless supply of sea wind to achieve the outcome.

Separately, Jason Poon Chuk-hung of Hong Kong Strategy Solutions pointed out that the public does not have a concrete idea regarding the cost of this project, with the government presenting a figure of HK$624 billion in March 2019, followed by an updated figure of HK$578 billion in December last year.

He said the decrease in the figure could be due to the government's removal of the estimated cost for the reclamation of roads and other related supporting facilities.

Poon estimates that the reclamation and construction of the entire Kau Yi Chau Artificial Island and other supporting facilities, such as roads and railways, could cost nearly HK$900 billion as of the middle of last year.