Manmade islands: A solution to urban overpopulation?

As cities look for new ways to manage rapid urbanization, more are seeing the water that surrounds them as a development opportunity rather than a constraint. Artificial islands are carefully constructed through land reclamation in bodies of water.

In Hong Kong, one of the most densely populated cities on the planet, land constraints have contributed to astronomical rents in commercial and residential markets, creating a housing shortage that has pushed over 200,000 people to “coffin homes” barely larger than a single bed.

With around 6 percent of Hong Kong’s land reclaimed by extending its shorelines, the government is now considering proposals for a vast manmade island that could house 1.1 million people, to be built in the 2040s.

“For cities constructing manmade islands, land scarcity is often the main driver,” says Rupert Davies, global research analyst at JLL. “Reclaiming land can help overcrowded cities to respond to urban growth by creating the additional space they need.”

Singapore, which has a higher population density than Hong Kong, has expanded its land mass by 25 percent thanks to several decades of reclamation. While its commercial and residential real estate prices are high, they’re well below those in Hong Kong: “Land reclamation has been a method for Singapore to stay competitive by allowing supply to stay more in line with demand,” notes Davies.

Expanding cities can have a green impact

Some cities are examining artificial islands as a means to mitigate environmental impacts of urbanization. Off the southwestern coast of Copenhagen, plans are afoot for a manmade archipelago of over 740 acres using earth excavated during construction of the city’s newest metro line, recycling much of the waste from the process. On completion, the new land will be home to a business and infrastructure district for green industries, including what would be Northern Europe’s largest waste conversion plant.

“Created from scratch, manmade land provides a blank canvas,” says Davies. “The Palm Islands, an archipelago of artificial islands off Dubai’s coastline, was designed to be iconic and further elevate Dubai’s tourism economy to attract the luxury hotels and resorts, and the very wealthy.”

Developers don’t need to work around existing buildings and infrastructure but can instead incorporate the latest technology and innovations in urban design. Take South Korea’s Songdo, a city built to be a high-tech, sustainable utopia. “The hope is for these ambitious projects to be the catalyst for new industries to grow and have a transformational economic impact”, says Davies.

Tokyo Bay is home to another such transformational project; the New Sea Surface Disposal Site is an island built on trash collected from the greater Tokyo region, and covered by a layer of soil. The island is part of a 1000-hecatre marine site that will one day be converted into parkland, with one 150-hectare region already covered in grass and slated for completion after the 2020 Tokyo Olympics.

Challenging land reclamation

But creating a manmade island is far from a panacea for rapid urbanization. Critics say construction often comes at the expense of wetland habitats for birds and marine life. “In some cases, the environmental impact has been devastating to local ecosystems,” says Davies.

Reclaimed land may be more susceptible to the impact of climate change because manmade islands aren’t built much higher above sea level – and there are significant costs to maintaining shorelines against flooding and erosion.

Following a typhoon, for example, Osaka’s Kansai Airport, built on reclaimed land, was flooded and had to temporarily close. And Dubai’s planned offshore playground for the rich and famous, a man-made archipelago of 300 islands known as The World (a sister project to The Palm Islands), is being gradually reclaimed by the sea after the project folded in the wake of the 2008 financial crisis.

Artificial islands for model cities?

While such ultra-luxury tourism projects are far from the norm, manmade islands could, however, showcase other models of urban life.

Amsterdam has long reclaimed land around city limits to provide living space for its growing population, and its reclaimed IJburg archipelago has been designated the site of 18,000 affordable new homes, with several of the islands built to be energy self-sufficient.

However, the scale and resource requirements of such projects mean that the majority of cities facing land scarcity are likely to consider a host of different options before land reclamation.

“Artificial islands are expensive, risky undertakings that can span decades” says Davies. “Due to the amount of time it takes for the land to be reclaimed and ready for use, such projects must be approached with long-term perspective. On top of this, further investment into transport infrastructure to and from the new land will be substantial.”

“Though reclaiming land can help alleviate overpopulation and pollution in inner cities, densely populated cities that are facing rising property prices, overcrowding and pollution have alternate initiatives to consider before the challenge of building an artificial island,” says Davies.

In the UK, for example, to relieve the pressure on London’s housing market the government is instead investing in improving transport links and expanding the commuter belt through initiatives like Crossrail.

London’s growth has also fuelled plans to expand the city’s airports, which were fiercely opposed by local residents. Counter-proposals included building a new airport on an artificial island in the Thames Estuary.

Although this proposal has since been abandoned, land reclamation has proven to be an effective solution when a growing city requires a new or larger airport. “One of the most successful scenarios for reclaimed land has been in creating space for airports that can operate 24 hours a day, away from densely populated areas and noise regulations of city limits,” Davies says. “Furthermore, the development doesn’t impact on existing land use, nor impact historical and cultural areas.”

Until advances in technology make it cheaper, the cost of building manmade islands is very prohibitive – for now. But with urban populations predicted to soar, cities need options. And with water accounting for 71 percent of the world’s surface area, manmade islands offer an alternative to building higher or further inland for cities of the future – even with all the cost and complexity involved.