Reviewing Adequacy of Drainage Systems following Flash Floods Due To Recent Monsoon Surges

Mr Saktiandi Supaat asked the Minister for Sustainability and the Environment in light of the monsoon surges in January 2025 (a) how many different areas reported flooding of (i) up to 0.5 metre (ii) between 0.5 and 1 metre and (iii) more than 1 metre above ground level; (b) out of these areas, how many have reported previous incidents of flooding in the past five years; and (c) what is the Ministry’s strategy to prevent and respond to flooding situations going forward.

In January this year, Singapore and the region experienced two monsoon surges which brought about prolonged rain. The first monsoon surge lasted four days from 10 January to 13 January, and the second monsoon surge lasted three days from 17 January to 19 January. From 10 January to 11 January, a total of 255.2 millimetres of rainfall was recorded at Changi, which is more than our average monthly rainfall of 222.4 millimetres in January.

Over these two monsoon surges in January 2025, there was one incident of flooding, which occurred at Jalan Seaview. Jalan Seaview is a low-lying area subject to tidal influence. Since the 1980s, a tidal gate has been put in place in the outlet drain downstream of Jalan Seaview, to help mitigate tidal flood risks for this area.

On 10 January, heavy rain coincided with high tide and this led to the flooding at the side road bend, a stretch of about 50 metres, of Jalan Seaview. The flooding on the road was about 0.3 metres and lasted close to three hours due to the high tide. The house next to this road experienced flooding within its car porch area. Based on the Public Utilities Board's (PUB's) records, in the past five years, this is the only stretch of road along Jalan Seaview that has experienced flooding.

While PUB had upgraded the roadside drains at Jalan Seaview in 2014 to increase their drainage capacity, some areas in the vicinity of Jalan Seaview are still susceptible to flooding as the road levels are marginally above the high tide level. The longer-term plan is to reclaim and build "Long Island" which will protect the East Coast area, including Jalan Seaview, from rising sea levels and tidal floods. Agencies have initiated technical studies and are engaging the public and stakeholders to shape the plans for "Long Island".

We encourage developments in low-lying areas, including at Jalan Seaview, to put in place their own flood protection measures, such as deploying flood protection devices. To help residents and businesses, PUB has been issuing flood protection devices, such as flood barriers and inflatable sand bags, as part of the annual monsoon preparation and providing guidance on how to deploy these devices properly in a timely manner.

Climate change will increase flood risks in Singapore due to more extreme and unpredictable rainfall. PUB adopts a multi-pronged approach to enhance Singapore's flood resilience.

First, PUB continually upgrades our drainage infrastructure. The Government has made significant investments over the decades to upgrade drainage infrastructure, with about $2.5 billion spent since 2011. We have successfully reduced flood prone areas from approximately 3,200 hectares in the 1970s to less than 25 hectares today. PUB conducts regular reviews on the adequacy of the existing drainage system and considers the latest drainage design standards and climate change data. There are 19 ongoing drainage upgrading works, with six more projects slated to commence in 2025. We will spend about $150 million on these projects in FY2025. We are currently reviewing the drainage infrastructure plan for the next review cycle of FY2026 to 2030.

That said, it is neither practical nor prudent in land-scarce Singapore to keep building more drains or expanding our drainage infrastructure. Doing so, would require significant land and financial resources, which would then not be available for other important uses. To put things into perspective, flooding in Singapore is localised and typically subsides within an hour. It is, hence, more effective to build up flood resilience at a systems level, where building owners, developers, as well as the wider community, all play their part alongside the Government.

To this end, PUB works closely with building owners and developers on measures that have to be taken at the individual development level to strengthen flood resilience. PUB's Code of Practice on Surface Water Drainage provides requirements on minimum platform and crest levels for buildings and flood protection measures that building owners and developers must implement to protect their premises. Amendments to the Sewerage and Drainage Act were passed in November 2024 to ensure that owners and developers continue to operate and maintain the flood protection measures in their premises properly after implementation.

PUB also proactively engages the community to better prepare for and respond to flood incidents. PUB works with the National Environment Agency (NEA) to forecast intense rainfall and issue early warning of potential floods to better prepare the public ahead of flood incidents. PUB launched its flood preparedness campaign "Get Flood-Wise" in November 2024 and worked with partners, such as Grab and BlueSG, to share flood readiness tips with drivers and commuters.

Managing flood risks is a collective effort between the Government, businesses and the public. I encourage everyone to play their part in enhancing Singapore's flood resilience.

I thank the Minister for the reassurance that there are future plans to protect our coastal low-lying areas. I have two supplementary questions. The first one is, because it will take some time for us to build "Long Island" or longer infrastructure improvements, so, what are the interim measures, including more pumps that can be deployed quickly, especially when we are going to expect more of such monsoon-type of weather events?

The second one is, we have committed to certain investments in the longer run. Now that we start to see more frequent occurrences, do we expect to invest even more? And if so, are we in a process of determining how much this would be?

Thank you, Mr Speaker. I thank the Member for these questions. I think they are very thoughtful. Indeed, I think we need to look at both short-term as well as long-term measures. I think in the short run, we would like to see how we can prepare the public including residents, better, faster and give them more effective means to protect themselves, including the availability of more devices to protect their own property.

Whether the pumps will be really effective in the case of Jalan Seaview, that may be doubtful because we are talking about the coincidence of both intense rain and high tide. So, it is difficult to pump something out if the tide is against you. What we really need to do is, where we can, for example, in Marina Barrage, we will start pumping ahead of time, prepare as much as we can, but still, more importantly is to get the local community, especially in the flood prone areas to be prepared themselves.

So, awareness, public engagement, early warning, advising public to sign up to PUB's channel for information. We are also working with the Land Transport Authority (LTA) to make some of these warning ahead of time more effectively through more platforms. These are all works in progress.

And in the longer term, we will want to review our flood drainage system, in tandem with our coastal protection system, because these are two sides of the same coin. In intense rain with high tide, as we have seen recently, we need to manage both together, and that is the reason why PUB is now the coastal protection agency. It is really to bring consideration, at the same time, plan for it and be prepared to invest in effective infrastructure that we have said that we are going to invest in significantly. We will review the plans, as I have said earlier on, for the next cycle of 2026 to 2030. We are in the process of doing that.

But the point that I like to make is that, even as we are able to foresee a greater occurrence of such extreme weather events, sometimes it is just not financially wise for us to prepare for the extreme events, because that will mean dedicating a lot of land, a lot of financial resources to protect us for those events that may not occur so regularly or in places where it does not occur regularly.

It is still the same message, that while the Government will look at improving our infrastructure, we need community, we need businesses, we need owners to also undertake protection measures to protect themselves, protect their properties and protect their families.

Thank you, Mr Speaker. I just have two supplementary questions. One is with regard to Minister's answer earlier, about the collaboration with NEA. Can the Minister share how the Ministry intends to collaborate with other agencies to ensure a coordinated flood response in the future, if it gets too extreme, that sort of scenario?

Second is, I think, the Minister shared earlier about flood mitigation measures for housing and corporates or individuals. Can the Minister share whether it is possible to have financial or logistical support available for residents and businesses affected by the floods and whether there can be budget allocation for future flood mitigation?

I think I have alluded in the earlier reply that we are working with NEA for better forecasts and also giving us more localised forecasts. Because, I think, when it comes to flooding, it is very localised, especially in Singapore when our floods occur in very small areas. So, it is all the more important for us to get very high resolution of forecasts in the very near term. So, that is something that we are working on, including with NEA and the Meteorological Service Singapore to have more sensors and better modelling in flood projection.

We are also working with LTA to try to get some of these traffic advisories out faster. For example, we are working to include some of these warning advisories in the ERP 2.0 so that we can receive the early warnings as we are driving. We are also working with the Singapore Police Force and the Singapore Civil Defence Force when it comes to emergencies related to floodings, in case there is a need to protect and save lives. So, there is close coordination between PUB and many related agencies.

On the need for financial support, I would say that actually the measures that we are putting in place really start from a very basic design. So, when it comes to developers, for example, we are expecting them to start putting in some of these budgets so that they can plan the infrastructure, the protection measures, as and when they are planning. This will be reflected in the land price and also in the development costs that they will be including in their development plans.

As to businesses as well as in the residential areas, I think PUB works very closely with them. In fact, over the years, we have been reducing the flood-prone areas significantly. I mean, when I was a child growing up, I remember that floods occurred in much wider areas more frequently, and many more businesses, including some in Chinatown, for example, quite regularly suffered from the impact of heavy rain and flooding. I think over the years, this has significantly been reduced. As I have mentioned, in the most recent monsoon surges, we only had one significant reported flood incident.

As and when they are needed, we will offer more help and we will keep a very close contact with the public and the businesses when it comes to engaging them on deployment of flood protection devices.