Singapore to employ mix of coastal protection measures

To hold back rising sea levels and prevent flooding episodes, Singapore will need to incorporate a mix of hard engineering solutions and soft armouring, like tapping natural coastal barriers.

Speaking at The Straits Times webinar on the rise in sea levels, Ms Hazel Khoo, director of PUB's coastal protection department, said the country is implementing regional coastal barriers and exploring methods such as nature-based solutions, and methods to weaken wave energy, to tackle the threat of coastal erosion.

She had previously noted that about 70 per cent of Singapore's coastline is guarded by hard structures, such as sea walls and stone embankments.

"What we will need to really protect Singapore from rising sea levels is to have a strong barrier that keeps the sea out. And with that regional protection, we can be assured that we can continue to have basements and more infrastructure development without compromising the resilience of our (urban) development," she said at the forum yesterday.

Panellist Zeng Yiwen, from the NUS Centre for Nature-Based Climate Solutions, said nature-based solutions may be cheaper options. Regenerating and conserving mangroves along some coastlines can guard the coasts as they buffer against storms and build up sediment to fend off rising seas. There are other benefits: Mangroves can soak up three times more carbon than forests can.

While noting that nature-based solutions can be a cheap alternative in some areas, Dr Zeng acknowledged that such methods may not be as extensively employed in land-scarce Singapore.

Urban areas are also at risk of more flash floods caused by extreme and erratic rainfall that comes with rising temperatures.

To tame the stormwaters, Ms Khoo said PUB has been using the "source-pathway-receptor" approach, which aims to make the entire drainage system adaptable to deal with unpredictable weather. For instance, it is looking at increasing and improving the capacity of the drainage system by widening and deepening drains.

Meanwhile, critical infrastructure such as Changi Airport's Terminal 5 and Tuas Port will be built at least 5m above sea level.

But ultimately, the root cause of sea level rise - planet-warming greenhouse gas emissions - must be tackled, Professor Benjamin Horton, director of Nanyang Technological University's Earth Observatory of Singapore, stressed.

"You need to remove the greenhouse gases to slow down the rates of (sea level) rise - then we can adapt, then we can live along the coastline, we can work along our coastline and our ecosystems can thrive," he said. "But if we don't get at the root cause, your adaptations are meaningless."