How Singapore handles floods and lessons for Vietnam

June 5, 2022 | 07:53 pm PT
Trinh Phuong Quan Architect
Reservoirs, rain gardens and constructed wetlands… there are countless ways for Vietnam to slow down water flow when it rains and increase drainage capacity.

I was born in the suburbs of Da Lat. There is a small yard in front of my home, filled with sand, pebbles and a few shrubs. Every time it rains the yard becomes a puddle, complete with frogs and insects singing in the night. The water is always gone by morning, leaving behind only dirt and dead leaves.

In 2018 I began working for Surbana Jurong in Singapore, one of the biggest infrastructure development consultancy firms in Asia. I got to work on architecture and urban planning projects for the first time. As an architect, I have to consider many aspects of construction beyond just design, like fire safety and water drainage.

Ever since it gained independence in 1965, Singapore has had to face two problems similar to what Hanoi and Ho Chi Minh City are having: urbanization and flooding.

Between 1990 and 2018 Singapore's population nearly doubled to 5.8 million. As a country close to the equator, it receives around 2,400 mm of rain a year, which is slightly more than what Hanoi and HCMC get.

How does Singapore deal with all that water? By leading it into reservoirs and the sea, thanks to its network of rivers and man-made channels.

But channels and sewers alone are not enough, especially for urbanized areas.

Singapore's National Water Agency (PUB) has not only mapped out water drainage improvements, but also collaborated with investors to build new structures such as reservoirs and rain gardens.

The Agency’s ABC Water initiative has helped shape the city into one of water and gardens. Its methods have succeeded in retaining rainwater and treating it close to the source before leading it into sewers.

Flexibility is Singapore’s key to dealing with large volumes of rainwater without causing floods simply by slowing the process down.

Investors and individuals are encouraged to adopt ABC Water’s designs to lessen the impacts of urbanization. Environment-friendly features such as rain gardens and constructed wetlands not only improve water quality, but also foster biodiversity.

In a quickly urbanizing Singapore, several structures such as roofs, parking spaces, roads, and pavements are made of waterproof surfaces. It means water cannot get underground, and heavy rains can overwhelm public sewers, leading to floods.

Things like reservoirs can provide a temporary space for water to flow into. The water can then be released in a controlled manner into the drainage system, preventing peaks that could trigger floods. Reservoirs can be placed either under or above ground, and are a requirement.

Starting in 2014, all industrial, commercial, residential, and school projects with an area of 0.2 hectares and more are required to control the peak water flow.

Reservoirs also need to be able to empty themselves within four hours after a heavy rain.

The Stamford detention tank is a recent solution by the PUB to temporarily store rainwater and keep it away from sewers during heavy rains.

It is capable of containing up to 38,000 cubic meters of water, equivalent to 15 Olympic-sized swimming pools.

Gardens on the roof are another low-maintenance solution to storing water using layers of plants. They help slow down water flow from the roof during rains, save water for irrigation, improve air quality, and cool down the surrounding environment.

For all its innovative solutions against flooding, Singapore has suffered from some very severe floods, such as in Orchard Road in 2010 and Upper Changi in 2018.

Solving flooding issues requires careful investment, the integration of many different solutions, a sufficient time frame, and a clear road map.

We can always learn from one another and, depending on the country, budget, geographical features, and weather conditions, decide how to best apply each other's lessons.

Three months ago I returned home to Vietnam to visit my family after months of being stuck abroad due to Covid-19.

I felt lucky to have been born in the countryside, raised in the city and pursued an education and career abroad.

Rural areas might not be as developed as urban ones, but they do have rain gardens and constructed wetlands. Cities can learn a thing or two about them.

*Trinh Phuong Quan is an architect pursuing a master’s degree at Stanford University in the U.S. The opinions expressed are his own.

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