Building Up Our Inland Flood Resilience

Singapore Green Plan
5 min readMar 4, 2022


“Oh man, the rain is crazy heavy today!” This is a phrase you might hear often these days, as Singapore experiences more intense storms due to climate change.

Most times, our drains are able to cope with the rain we receive. However, extremely heavy rainfall — which may occur more frequently, at more intense levels, and at times when they are not usually supposed to — can sometimes exceed the capacity the drains are designed for, especially when it occurs in low-lying areas.

Over the decades, PUB, our national water agency, has made strides to reduce Singapore’s flood prone areas, from 3,200 hectares in the 1970s, to just 28 hectares today. In the last decade, almost $2 billion was invested to expand and improve our drainage infrastructure! Even today, PUB works continuously to monitor flood prone areas and enhance flood resilience.

Wide-spread flooding occurred often at low-lying areas in the city centre during the 1960s and 1970s. (Image Credit: PUB)

How Exactly Does Our Drainage System and Flood Response Work?

Being in the tropics, Singapore experiences abundant rainfall throughout the year — over 2,200mm a year on average.

Two thirds of Singapore’s land area is used as water catchment. Rainwater that falls on these areas is collected through an expansive network of drains, canals, and rivers before it is channeled to our 17 reservoirs.

Reservoirs in Singapore. (Image Credit: PUB)

To enhance flood protection, PUB has adopted the “Source-Pathway-Receptor” approach since 2012 as a holistic stormwater management strategy. This approach addresses flood protection not just through widening drains and canals (“Pathway”), but also in areas where stormwater runoff is generated at its source (“Source”), e.g. through the building of underground detention tanks, and where floods may occur (“Receptor”).

Image credit: PUB

Ever wondered why you have to climb a flight of stairs or walk up a ramp before descending into an underground MRT station? That’s because the entrance to the station is designed to be higher than the adjacent road or ground level for flood protection!

PUB has an island-wide drainage improvement programme to continually upgrade our drainage infrastructure to cater for new developments, alleviate flood risks and rehabilitate aging infrastructure. These improvements include widening and deepening our drains and canals, constructing diversion canals and catchment level detention systems. However, it is not always feasible or cost-effective to build bigger drains and infrastructure to cater to every extreme rainfall scenario, due to Singapore’s land constraints.

Find out more about how we manage floods in Singapore using drains and drainage infrastructure like the Stamford Diversion Canal and Stamford Detention Tank!

Find out more about our drains and drainage infrastructure like the Stamford Diversion Canal and Stamford Detention Tank!

Today, PUB has more than 500 water level sensors installed in drains and canals island wide and a network of over 1,300 CCTV cameras (including LTA’s traffic cameras), to monitor the drainage system and real-time site conditions during heavy storms to ensure timely response.

Since late last year, PUB has been rolling out new initiatives to enhance rainfall forecasting, monitoring, and flood response capabilities to keep public and motorists out of harm’s way during flash floods. These include a fleet of 13 new flood response vehicles — now equipped with a GPS tracker and a pan-tilt zoom camera to stream real-time vehicle locations and flood conditions on the road to PUB, as well as equipment such as portable flood barriers. PUB also provides flood barriers to residents and businesses in low-lying areas and flood hotspots.

New flood response vehicles (Image Credit: PUB)
Pan-tilt camera to stream real-time vehicle location and flood conditions on the road to PUB (Image Credit: PUB)

You can also get the latest updates on potential flash floods by subscribing to PUB’s Telegram Channel at! And check out the useful guidelines below to stay safe during rainy days!

Flood safety tips (Image Credit: PUB)

Active, Beautiful, Clean Waters (ABC Waters) — Not Just A Park Feature

Our parks, which feature beautiful streams, aren’t just to beautify our community. There has been conscious effort to integrate our drainage infrastructure with the urban environment to enhance overall livability.

Over the years, Singapore has gradually developed a pervasive network of about 8,000km of waterways and 17 reservoirs for our water supply. In 2006, PUB launched the Active, Beautiful, Clean Waters (ABC Waters) programme to transform Singapore’s utilitarian drains, canals and reservoirs into beautiful streams, rivers and lakes that are well-integrated with the surrounding landscape. These naturalised waterways and waterbodies can provide multi-functional uses such as flood protection, recreation for park visitors and habitats for biodiversity.

Do you know where they are? Just to name a few, there is the Kallang River at Bishan-Ang Mo Kio Park and Alkaff Lake in Bidadari Town, Rochor Canal and the Bukit Timah First Diversion Canal (Holland Plain)!

Where possible, our concrete canals are transformed into natural rivers, or reservoirs into natural lakes, so that they can hold more water during times of intense rainfall. The Kallang River at Bishan-Ang Mo Kio Park is one example. (Image Credit: PUB)

There are a variety of nature-based solutions, such as bioretention swales, which can help reduce flooding by conveying, retaining and slowing stormwater runoff, while helping to clean the water at the same time. Find out more here.

Find Out More

Interested to find out more about inland flood protection in Singapore? Check out these links for more info:



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