With 7096 people per square-kilometre, Hong Kong is the world’s fourth most densely populated city, according to the United Nations. Hong Kong’s population is also set to increase from 7.34 million (in 2016) to a peak of 8.22 million in 2043 . Hence, one of its most pressing issues today and for the future, is the lack of available land for housing and development.
Hong Kong’s government is in pursuit of land reclamation to cope with a dearth of land supply. In a 2019 policy address from Carrie Lam, the Chief Executive of the Hong Kong Special Administrative Region of the People's Republic of China, it was recognised that reclamation in the Central Waters for developing the Kau Yi Chau Artificial Islands could provide 1000 hectares of land and space for future generations.
This is the question for Hong Kong: will land reclamation from the sea provide the required space to house the next generation of its citizens and supply enough land for future developments?
There are major challenges to land reclamation from the sea, including:
Understandably, people in the community have concerns about the development of artificial islands, for instance: why extensive reclamation is required, for whom new land supply and housing are provided and how environmental protection and cost-effectiveness are ensured.
This thinking paper considers the options for Hong Kong to reclaim the land it needs to accommodate its future expected population growth.
Hong Kong itself has limited materials available for reclamation use because its existing land is already supporting urban precincts. Construction and demolition materials – inert C&D materials – are often used in reclamation works, however, resource is limited and the supply is often unpredictable.
When considering importing materials by sea, Hong Kong needs to consider several factors to achieve optimal cost efficiency.
For critical materials such as sand, Hong Kong can explore importing from countries like Vietnam or the Philippines. For other materials, such as rock, Hong Kong should ideally look closer to home, within a radius of 300 kilometres. Besides cost, this approach can help save time and overcome the associated challenges with supply chain logistics and weather reliability.
China, for example, is a promising source for materials such as rock as this can be crushed before travelling overland to Hong Kong. There is also less chance of interrupted deliveries and workflows caused by typhoon activity. The other option is cavern engineering instead of moving the surface of hills and mountains in Hong Kong, excavation inside of a mountain can produce reclamation material for construction. Whilst these could be important sources of materials, rather than from the sea, the reliability of supply hinges on the quantity and output from the source.
There are quarries in Guangdong, China, that are accessible by approximately 200 kilometres of road and could prove to be the most cost-efficient and practical supply route. Still costly though, but more feasible logistically and worth considering for reasons of proximity, access to fit-for-purpose material and quality control.
This avenue presents other very real considerations too, including a high volume of incremental industrial vehicle traffic adding to the dust, noise, fumes and traffic congestion on Hong Kong’s already strained road infrastructure.
Will eyeing the sea be the remedy to Hong Kong’s need for more land?
The region is no stranger to land reclamation. It has long reclaimed land from the sea. However, controversy is growing over the perceived marine and ecological impacts from dredging further into the sea.
These are all questions of any marine reclamation however, on how to move material and minimise impacts on marine ecology. Today, compared to 50 years ago when dredging in Hong Kong first started, we have technological instruments that can assess the performance of the reclamation work before, during and after completion.
When reclaiming from the sea, extensive ground improvement works including jet-grouting, stone column, deep cement mixing and installation of prefabricated vertical drains are commonly used in Hong Kong.
With advancements in artificial intelligence and machine learning comes the opportunity to think of new dredging applications, to help assess the performance of the ground improvement work and the subsequent settlement of the reclamation. Integrated data management systems can collect and analyse data from sensitive receivers within the work zone and produce reports on the ground in near real time.
Artificial intelligence can be applied on data acquisition of ground settlement with land reclamation, and machine learning for estimation of ground subsidence over the design life of the reclaimed land. This application of big data and artificial intelligence algorithms to manage field data monitoring may significantly improve the traditional observation approaches for geotechnical design and analysis around studying the behaviour and forms of reclamation.
Deans Head, an earthquake-damaged cliff and landslide on the Port Hills of Christchurch, New Zealand.
Aurecon’s geologists in New Zealand have been using digital engineering to establish data management modelling for land reclamation. In the wake of Christchurch’s devastating earthquakes in 2010 and 2011, Aurecon actively used drone technology and digital rock joint mapping to determine the stability of cliffs and the remediation efforts required.
The same technology could be applied in Hong Kong to predict land movements in a secure and safe way, and then map out the land reclamation possibilities. The low-cost nature of using drones and photogrammetry is emerging to assist in planning and cost estimating sources of material for reclamation.
Remote sensing techniques aren’t new but haven’t been applied on many land reclamation projects. They could be used in Hong Kong to monitor and assess reclamation settlement along the coastal areas.
Artificial islands are being floated as solutions to some of the pressing challenges that Hong Kong is facing. However, with a 15 to 20-year construction time frame, they cannot mitigate the near-term housing crisis.
Learning from others, there is a significant settlement problem at Japan’s Kansai airport, which is built entirely on reclaimed land occupying two artificial islands in Osaka Bay. The engineering miracle is still no match for Mother Nature as it slowly settles all the way down to sea level, leaving it at risk of flooding, sea level rise and typhoons, as experienced during Typhoon Jebi in 2018.
If new reclamation is to be situated facing an open stretch of the sea, long-range Pacific Ocean phenomena must be considered as low-lying areas such as artificial islands are highly vulnerable to extreme weather and tides and storm surges, and more frequent flooding. Engineers, contractors and government must plan together to find practical ways to address problems and realise the idea of artificial islands, if it’s chosen as the solution to support growing populations. Provision of protective measures, such as building a higher and stronger embankment or raising the final formation level of reclamation, is costly.
Some environmentalists believe there are more cost-effective, less risky alternatives for land reclamation, with lower ecological impacts, such as brownfield developments. Such sites look better on paper, with lower costs, greater availability and less environmental impact, but still pose challenges for land development in the space-starved city of Hong Kong.
The brownfield sites are not idle land, they are occupied by businesses and manufacturing that provide jobs and contribute to the city’s economic stability.
Barangaroo Reserve and The Cutaway opened to the public in August 2015.
Barangaroo Reserve along Sydney’s western foreshore in Australia is an example of a brownfield site, transformed from a disused container terminal into a waterfront park.
The blank canvas was six hectares of flat asphalt and Aurecon was part of the land reclamation project to build up the naturalised landscape. Digital engineering tools were used to determine the required size of each of the 10,000 sandstone blocks to be extracted from underneath the site and used to extend the foreshore into the water. While this type of scenario would not be entirely the same for Hong Kong, it is a good example of the integration of environmental, ecology reserve, coastal and geotechnical engineering practices together on shoreline protection works design a key part of land reclamation from sea.
In the future, we might see the application of digital engineering to protect marine ecology in areas where reclaimed materials from the sea are used to extend countries such as Hong Kong. Living seawalls are already under trial that provide marine seawall structures to protect marine life and biodiversity. This type of application could become part of the answer to add more land to those countries surrounded by sea and are also growing in population.
Digital engineering provides project owners, engineers and contractors with new ways to envision and deliver land reclamation projects, to innovate and develop solutions that push the boundaries of imagination and creativity.
Worldwide, governments and engineers need to think of the future, about the type of reclamation materials that could be used to solve Hong Kong’s housing issues, especially if sourced locally and how and where land reclamation can be applied.
What might the future and our imaginations, hold for us? This is the question for lawmakers, engineers and environmentalists in Hong Kong today. If we learn from other global projects, consider how emerging technologies can help and plan together collaboratively, solutions will evolve that give people confidence to plan their future in Hong Kong.
Dr. Sing-Lok Chiu is a Technical Director at Aurecon, working as a member of the geotechnical team in Hong Kong. With more than 30 years of experience in the industry, S-L is a recognised expert in infrastructure projects, including various sizable foundation and basement construction works for metro railways, as well as building developments in urban areas, and reclamation and ground improvement works. He has also been actively involved in case investigations and due diligence studies of geotechnical issues for land development and ground improvement projects.
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