Water crisis: Impact on Singapore

Rising seas threatening Singapore's reservoirs?

Climate change poses risk to water supply, but offers opportunities too

A sufficiently high tide paired with a large storm could potentially sweep seawater into Marina Reservoir (above), says Assistant Professor Yuan Jing from NUS' department of civil and environmental engineering. ST PHOTO: MARK CHEONG

Jose Hong

Updated

Published

Oct 28, 2018, 05:00 AM

Singapore's water success story is well known, but climate change could cast a shadow over that progress.

For example, if sea levels rose high enough due to the melting polar ice caps, a sufficiently high tide paired with a large storm could potentially sweep seawater into Marina Reservoir, said Assistant Professor Yuan Jing from the National University of Singapore's (NUS) department of civil and environmental engineering.

Such an episode, he said, "would destroy the water quality for a long time". He also said rising sea levels would affect the feasibility of possible future underground reservoirs.

"We might want to build underground reservoirs, and rising sea levels may lead to the intrusion of seawater through the rock, jeopardising their construction."

In 2015, national water agency PUB announced that it was exploring the possibility of storing excess storm water underground.

Prof Yuan said the Singapore Government does have long-term plans for developing the coast. But he was flagging that the scenarios should be considered. He also qualified that all these potential threats were deep into the future and there was a "huge level of uncertainty" regarding these predictions.

Indeed, uncertainty is a key theme of climate change, one that the authorities have long recognised. In January, the Building and Construction Authority (BCA) said projections for sea-level rise could change and that the country's framework for coastal protection therefore needed to be flexible.

In 2010, the BCA itself carried out shoreline restoration works to stabilise a section of the beach at East Coast Park. This consisted of large sand-filled bags, laid several metres into the ground to be level with the low tide, helping to reduce sand erosion.

And two years ago, during Singapore International Water Week, Minister for the Environment and Water Resources Masagos Zulkifli said: "Climate change results in a new normal of uncertain weather."

He said one of the ways Singapore hoped to mitigate this uncertainty was through water sources that did not depend on the weather, such as desalination.

Speaking to The Sunday Times, NUS' Professor Ng How Yong echoed this sentiment.

"I think the climate change threat to Singapore's water isn't very high because we get our drinking water from our four national taps," he said, referring to the country's local catchment water, imported water, Newater and desalinated water.

"Even in the past, when we had a very dry season, our taps still flowed because we had alternative sources of water."

But if the country relied more on desalination, the cost of producing drinking water might go up, he said.

Professor Shane Snyder, executive director of the Nanyang Environment and Water Research Institute (Newri) at Nanyang Technological University, said his institute is developing ways to make the desalination process far less energy-intensive.

"At the same time, Newri is developing new membranes that can be used in wastewater treatment to greatly improve the quality of reused water, while making the treatment process far more efficient," he added.

Unpredictable and more intense rainfall brings other dangers. When the ground stays parched for long periods, it may lead to more polluted storm water that enters drains and reservoirs once it rains.

NUS' Professor Hu Jiangyong, in a joint project with the PUB, has come up with a way to combat this through "bioretention systems", more commonly known as rain gardens. Plants and soils are arranged in a specific way that purifies storm water, while also beautifying the environment, said Prof Hu.

PUB's first pilots of the system removed up to 80 per cent of suspended particles and 45 per cent of nutrients such as nitrogen and phosphorus in storm water. Prof Hu's newer versions use less sand and are more easily portable.

Already, she has worked with the agency to install more than 10 bioretention systems in schools around the country.

NTU's Prof Snyder said that if Singapore played its cards right, it could turn climate change problems into advantages.

"While climate change does threaten global water security, it also provides Singapore with an opportunity to disseminate our strategies and technologies to help other regions adapt to changing environmental conditions."