Protection from rising sea levels

It is timely that national water agency PUB is exploring the use of underground space to defend Singapore against rising sea levels amid climate change and more intense rainfall. The agency says that a study to assess the feasibility of using an underground drainage and reservoir system to combat inland and coastal flooding will start in 2023. Findings from the study will complement ongoing and planned studies looking at how different segments of Singapore’s coastline could be better protected from going underwater. What lends a degree of urgency to the PUB’s latest initiative is that, by the end of this century, the average sea level surrounding Singapore could rise by up to 5m because of the combined effects of climate change and other factors such as storm surges and tidal activity. This means that about 30 per cent of Singapore would be vulnerable to going underwater.

Addressing the Singapore context directly, the PUB notes that sea-level rise is driven by climate change and global warming. As more greenhouse gases are released and trapped in the atmosphere, the planet heats up. This leads to the melting of polar ice caps and glaciers, which increases the amount of water in oceans. As seawater warms, it also expands, contributing further to the rise in global sea levels. Today, average sea levels are rising at a rate of 3mm to 4mm a year. To resist rising seas, the PUB commenced the development of a flood model in 2021 to assess flood risks holistically. Also, the agency has been studying engineering solutions with nature-based enhancements to hold back the rising seas. These solutions include sea walls, earthen bunds, revetments – a facing of stone or other armouring material to protect a streambank or shoreline – and mangroves. The agency carries out specific studies in vulnerable areas.