The site is on a flood plain along the Shenzhen River that forms the boundary between Hong Kong and mainland China.

Lam, the honorary president of the Hong Kong Bird Watching Society, asked why the government had to develop its I&T hub there, when the 151 hectares of wetland, including fish ponds, could store floodwater and ease the impact on nearby settlements.

“It is a strange decision to develop the area with industry creating wealth,” he said during a visit to the site with the media last Tuesday. “If anything happens, it will halt production and affect the supply chain.”

He recalled severe flooding in Thailand in 2011, which disrupted production at many companies including technology firm Western Digital and car giants Honda.

He suggested developing the I&T hub elsewhere, in the upper course of the Shenzhen River such as at Heung Yuen Wai in Northern district.

Hong Kong is prone to extreme weather risks and three city universities predicted last month that the city would experience its highest hourly rainfall of 230mm in the 2040s.

That would be more than two-fifths higher than the 158mm record set during the city’s “once-in-500-years” rainstorm in September.

In a reply to the Post, the bureau said the technical assessment of the area had considered the impact of future sea-level rises and increased rainfall due to climate change. The site would be equipped with facilities to manage floodwaters, it added.

“If necessary, relevant departments will further enhance the overall capacity of the drainage system,” a spokeswoman said, adding the government had been reviewing the resilience of projects in response to recent extreme weather events.

The government in May revealed its latest development plan for San Tin, with 300 hectares expected to house leading I&T companies and the rest for a city centre with 50,000 flats.

The plan will involve filling in 90 hectares of fish ponds, but the government said half had not been used for aquaculture or had been abandoned for many years.

Hong Kong aims to earmark 300 hectares of land for I&T purposes near border

It said any ecological loss would be compensated for at future wetland parks being planned, including a proposed 338-hectare site at Sam Po Shue.

Officials earlier said the government could not guarantee the preservation of all existing wetlands and would focus on ensuring quality, not quantity.

But the Bird Watching Society expressed doubts over the proposal and said two bird species were no longer staying in the city to breed after fish ponds in Yuen Long were filled in for private residential development in the 1970s.

That was despite the Mai Po nature reserve being set up. One of the species that was no longer breeding was the pheasant-tailed jacana, a water bird considered a protected species in China.

Wong Suet-mei, the society’s conservation officer, said: “The experience shows that no matter how hard we try to compensate for the impacts of development, it does not succeed. Now the city is repeating what happened 50 years ago. Isn’t this going backward?”

The green group said the site was a bird haven, with records of 117 bird species of special conservation value.

During the three-hour media tour last Tuesday, 51 bird species were spotted, including the endangered black-faced spoonbill and the collared crow listed as globally vulnerable.

About 45 hectares of ponds are still active, with 56 operating pools that are part of the Fishpond Conservation Scheme begun in 2012 for fish farm operators to allow birds to prey on residual organisms such as fish with low economic value.

If the government proceeded with its plan, this ecological contribution by the fishery industry would go to waste, said the NGO’s director, Yu Yat-tung.

The environmental impact assessment report of the San Tin development is being considered by environmental authorities, but the green group questioned whether the government had bypassed statutory procedures as the report was based on an earlier proposal that did not include removing wetlands.

The bureau said it had earlier notified environmental authorities of the latest proposal and received a green light to proceed with the report, which would cover an ecological assessment on filling in the fish ponds.

Over 25% of Hong Kong bird species live at farmland in Northern Metropolis: survey

Lam said reclaiming ponds was a “backward” land development method at a time when China was focused on environmental conservation.

He said the Futian Mangrove Wetland in Shenzhen was designated one of the wetlands of international importance last year.

Pointing out the proximity of the San Tin area to the Mai Po Inner Deep Bay Ramsar Site, designated as a wetland of international importance in 1995, Lam urged the government to notify the intergovernmental treaty, The Convention on Wetlands, about the I&T hub plan as it could affect the internationally recognised nature reserve.

The bureau confirmed that 0.1 hectares of the San Tin site overlapped with the Mai Po wetland and it would suggest including that piece of land and nearby area in the future wetland park.

It added that it would construct low-rise blocks to minimise the impact on bird flight.

The San Tin project is one of the development schemes under the Northern Metropolis plan to turn 30,000 hectares into an economic and housing hub in the New Territories near the border with the mainland.