THIS was how the worst flood in Selangor happened, according to Universiti Kebangsaan Malaysia’s climatologist Prof Dr Fredolin Tangang: the remnant of a tropical depression that had caused floods in the eastern state of Terengganu, Kelantan and Pahang on December 16-17, instead of petering out, gathered strength and continued its move inland towards the Straits of Malacca.

This triggered continuous, heavy rainfall in the west coast, resulting in the worst flood in Selangor during the weekend of December 18 and 19.

The tropical depression was first spotted off Sarawak and the South China Sea on December 15 before moving westward to Peninsular Malaysia.

A tropical depression is formed by air that moves towards lower areas, rises and creates thunderstorms with strong winds. When it travels overland, it is supposed to peter out.

The lesson here is that we can no longer assume the monsoon season of October to March will cause the traditional massive floods only in the east coast states, as it can been seen now it also happened in the west coast of Selangor, Kuala Lumpur and Negri Sembilan.

Also, when the remnant of that tropical depression gained strength as it travelled inland instead of petering out, this gave an element of unexpectancy when the volume of rainfall in Selangor on that fateful day in 24 hours was worth the volume of rainfall in a month.

This implies the worst flood in Selangor is an unexpected event when despite everybody was caught with their pants down, it was then politicised by “pants- down” politicians of all hues to whack one another.

A repeat of this incident is possible in the coming days and weeks, as it had happened before some time ago in Sabah, Johor and Penang where it had also triggered worst floods.

Moreover, Malaysia is now facing the northeast monsoon season from October to March, bringing in more monsoon rain. Until March is over, who can say that the worst is over?

Although March is at the tail end of the monsoon season and thus, unlikely for the worst flood to occur in that month, again who can say the worst is over, if we factor in climate change with its frequent and unpredictable rain and flood?

Meanwhile, there should be a rethinking on the approach to flood mitigation by working with nature and treating water as our ally by respecting its natural need to run its course and occupy space.

When rain falls, some portion of it seeps underground being absorbed by the forest and soil. The balance of the rainfall will be water flowing on the surface known as surface run-off, some of which will join the river that will continue its journey to the sea.

The balance of this surface run-off that is neither absorbed by the forest and soil nor join the river will end up at a dead end in freshwater swamps and lakes.

This is nature’s way of making lakes and swamps as a container or natural storage tank to accommodate the need for water to run its course, so that flooding will not occur.

No more is this shown to be very successful than in the Netherlands where the Dutch, who are very experienced in water management, having dealt with sea-level rise and river floods long before climate change became a concern, had turned previous flood mitigation efforts on their head.

While more than half the country lies beneath sea level, and the ocean is held back by more conventional flood control methods, the country’s river management has changed drastically.

For a long time, river water management projects have worked against nature, when what the river is telling us is it needs more space.

In 2007, the country began a US$2.7 billion (RM11.3 billion) project called Room for the River along the Maas and Rhine Rivers to control flood by creating catchment areas that often mimic the natural flood plains.

Since then, more than 30 such projects along the Maas and Rhine Rivers have been completed in which the catchment areas function like a natural huge tank that allows the river water to fill up space, thereby reducing the water level in the river proper by an amount enough to prevent a catastrophe.

In July, for instance, Dutch officials had celebrated the completion of a new flood control project, where instead of damming or diking the Maas River and its tributaries, as conventional flood control would do, they had decided to work with nature – diverting the waters into a 1,300-acre flood plain created to duplicate the river’s old overflow channels.

Later in that month, as if to test the viability of the new “radical” approach, as soon as the new flood mitigation project was completed, Europe was hit by a deadly torrential rain.

Yet, no one died in the Netherlands in that July flooding. Some tributaries did wreak extensive damage in the border region, but along the Maas River, which swelled to epic proportions, large urban centres stayed safe and dry.

The project, Maaspark Ooijen-Wanssum, a nature preserve near the city of Wanssum, lies at the heart of the new approach, where the flooding did exactly what it was supposed to, absorbing so much water that levels in parts of the Maas River dropped by 33cm, enough to avert a major disaster.

If the area had not been freed up for the nature preserve project to reroute the excess water from the Maas River, the nearby cities of Venlo and Roermond would have been flooded.

Nearer home, in Bangkok, the same approach of work with nature and give enough space for water to flow was applied in a flood mitigation project.

In 2017, an 11-acre land worth an estimated US$700 million was transformed into a lush, green oasis featuring ample space for outdoor meetings, an amphitheatre, a massive lawn for recreation, playgrounds and even a small museum.

Known as the Chulalongkorn University Centennial Park or simply CU Park, its most amazing part is the ability to hold nearly one million gallons of water during severe floods because constructing the park effectively means creating a flood-proof park by building it to flood.

The park was designed to sit at a gradual three-degree angle so that gravity pulls rain and floodwater from the park’s highest point – the green roof – to the lowest point at the other end of the park, where rain and flood water fills a retention pond.

Three large tanks below the roof and museum can hold up to 250,000 gallons of run-off water from the green roof. A lawn next to the museum also collects rainwater – more than 105,000 gallons of water. Rainwater also collects in four connected wetlands along the park.

Even if the entire city is flooded, the park can hold the floodwater, and eventually, water held by the park can be drained into the public sewage system when all the other flooding in the city has been drained.

Malaysia would do well to emulate Holland and Thailand by adapting these nature-friendly projects to the local context such as weaving in the “plant 100 million trees” scheme into flood mitigation projects by creating a series of nature preserves around Kuala Lumpur and Selangor that not only mimic the natural flood plains but also divert the water in the rivers of Selangor and Kuala Lumpur, just like the Dutch model.

Additionally, a series of flood-proof parks by building it to flood in order to alleviate the rising water level of the rivers in Selangor during severe flooding should also be considered as in the Bangkok model.

In the urban area, one way to mitigate flood is the construction of water absorbent roads that functions like the forest floor and soil where rainwater is naturally absorbed to the ground.

Urban development has drastically reduced the absorption rate of water to the ground via the construction of paved roads and highways, which will only increase the rate of surface run-off, causing flood resulting in submerged road.

But if the paved roads and highways are made of water absorbent materials, the scene of submerged roads may be a thing of the past. – December 31, 2021.

* Jamari Mohtar is the editor of Let’s Talk!, an e-newsletter on current affairs.

* This is the opinion of the writer or publication and does not necessarily represent the views of The Malaysian Insight. Article may be edited for brevity and clarity.