PUB trials new flood protection barrier that can be deployed quickly

PUB assistant engineer Vincent Tay installs a portable flood barrier during a demonstration. ST PHOTO: MARK CHEONG
PUB assistant engineer Mohammad Fahmi Vasmin tightens the bottom bolts of a floodgate during a demonstration. ST PHOTO: MARK CHEONG
A floodgate, reinforced with inflatable flood bags, which inflate within minutes of contact with water. ST PHOTO: MARK CHEONG

SINGAPORE - A new flood protection barrier is being trialled by the national water agency PUB in preparation for heavy rainstorms and flash floods during the monsoon seasons.

The new device, known as Floodgate, is the latest addition to a repertoire of flood barriers which can be quickly deployed to protect homes and buildings in the event of a flash flood, said PUB in a statement on Wednesday (Dec 30).

Made from high-strength steel frames wrapped in a waterproof rubber sleeve, the device is expandable and can be installed at the entrances of residential, commercial and industrial premises.

Suitable for wider doorways, Floodgate offers the public more flexibility in choosing a barrier to be placed in front of their premises.

The device is available in different sizes, each with a fixed height of 0.68m and widths ranging from 0.77m to 1.52m wide. The units can also be linked together to create longer sections to fit wider entrances, such as shopfronts.

Each unit will cost between $800 and $2,200, depending on its size.

To test its effectiveness, 20 pieces were purchased from the United Kingdom in September, with 15 currently being tried out by residents in Upper Paya Lebar Road in the current monsoon season.

With the north-east monsoon season expecting to persist for another month or so, the frequent rainstorms may cause flash floods in areas where the capacity of the drainage system is overwhelmed, particularly in low-lying ones, said PUB.

According to the Meteorological Service Singapore (MSS)'s website, the north-east monsoon season lasts from December to early March, though its wet phase is typically from December to early January.

This year, there has been seven days of flash floods occurring at various locations in Singapore due to very intense rainfall within a short period.

The most recent flash flood occurred on Nov 7, when heavy rain overwhelmed roadside drains in Aljunied Road, causing runoff to accumulate on the road for around 20 minutes.

According to the MSS, the highest daily total rainfall recorded that day was 100.2mm in Tanjong Katong - the second-highest recorded in a day for the first half of November.

As of Dec 29, the highest daily rainfall total this year was 185.2mm recorded on Jan 29 at Jurong Island.

Since last year, PUB has begun lending out two types of portable flood barriers to homes and shophouses in flood-prone and low-lying areas as part of its efforts to enhance its flood-response capabilities.

This includes extendable panels, known as the Dam Easy Flood Panels, which are suitable for doorways prone to flood waters. Each equipped with an inflatable seal, they are around 0.6m high, and can be adjusted to fit a doorway ranging from 0.78m to 1.10m.

They weigh around 20kg each and cost $1,200 per set.

PUB assistant engineer Vincent Tay installing a Dam Easy Flood Panel during a demonstration on Dec 30, 2020. ST PHOTO: MARK CHEONG

The second type are portable flood barriers, which can be erected on roads and pavements by creating a 0.5m dam to divert or contain floodwaters away from an area.

Each set consists of 10 sections, which are around 3.4kg each and can extend to 6m in length.

So far, 65 pieces of Dam Easy Flood Panels and 155 pieces of portable flood barriers have been loaned out.

(From left) Dam Easy Flood Panel, a Floodgate, and inflatable flood bags, which inflate within minutes of contact with water. ST PHOTO: MARK CHEONG

Mr Yeo Keng Soon, PUB's director of Catchment and Waterways Department, said: "Flash floods these days are more localised and typically subsides within 30 minutes. However, we are seeing more frequent rainfall events that... (increase) rainwater and (bring about) more intense storms. With climate change, we must be prepared to... enhance community resilience to flash flood occurrences as it is not always possible to widen or deepen our drains to eliminate floods.

"PUB is constantly looking out for new solutions and devices to better enable residents and businesses to respond to flash floods and minimise potential damage to their premises."

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