ENVIRONMENTAL concretisation and overdevelopment are the main factors for repeated flash floods in Kuala Lumpur, said experts.

They said this, coupled with climate change acceleration, will see the capital city inundated more frequently in future.

They added that the development of water retention ponds in the Klang Valley may have also contributed to the recent flooding.

Former National Hydraulic Research Institute of Malaysia director-general Salmah Zakaria said the Sungai Klang basin’s development is so dense that a large portion of the area is paved – either by concrete or tar.

This increases the overland flow when it rains, she added.

“Before urbanisation, rainwater was intercepted by vegetation. The water would infiltrate into the ground and take time to travel to rivers,” she told The Malaysian Insight.

“After urbanisation, rainwater swiftly collects from roofs and other paved areas, flowing into drains, which efficiently carries it to the nearest rivers.

“If you look at satellite images of the Sungai Klang basin, the area is totally paved. You can have flash floods within one hour.”

There were 48 flash floods in the Klang Valley between 2015 and 2020. There were five in 2017, and 13 in 2020 – an almost trifold increase.

Salmah said rivers’ diminished capacity due to siltation from erosion and indiscriminate construction of hill slopes near rivers and river reserves is another factor that causes flash floods.

The Sungai Klang basin consists of seven rivers – Sungai Ampang, Sungai Batu, Sungai Damansara, Sungai Gombak, Sungai Kayu Ara, Sungai Kerayong and Sungai Klang.

Salmah pointed to New York and London, cities where a river system runs through them but no flooding has been reported, saying this is because the cities are vertically built.

“In other cities, they build vertically, meaning high-rise buildings. This is to ensure the space for water is not taken up. The ground floor is for the water to flow.”

Flash floods crippled the capital city on March 7, just months after massive floods hit the region in December – the worst in the history of the Klang Valley since 1971.

Last year’s inundation led to millions of ringgit in damages and saw parts of Kuala Lumpur and Shah Alam submerged, while last week’s brought the city to a standstill.

Following the flooding, the status of six of 15 water retention ponds in the capital came into question, as an auditor-general report found that the ponds were approved for development.

The six water retention ponds are Batu, Batu 4 ½, Delima, Nanyang, Taman Desa and Taman Wahyu.

“(The development) can contribute (to flooding), but it is not the sole factor. The development of the six ponds is in the area of the Sungai Batu basin,” said Salmah.

“But the Sungai Klang basin is more than Sungai Batu’s. The water being brought down to the capital city is also from other rivers.

The six ponds could have been the main factor if flooding occurred after they were developed, but flash floods have been happening even before their development, she added.

Kuala Lumpur Lands and Mines Department director Muhammad Yasir Yahya said the Batu, Delima, Nanyang and Taman Wahyu ponds will retain their existing functions despite approval for development.

The other ponds will undergo upgrading works instead, he added, giving an example of the one in in Batu 4 ½, which will house a public recreational park and retain its main flood prevention function.

The approval to conduct mixed-development projects at the ponds in Batu 4 ½ and Taman Desa has been revoked, he said.

Make the Klang Valley spongy

Sahabat Alam Malaysia president Meenakshi Raman said Malaysia needs to look past improving the drainage system and plan for climate resilience.

“We are not planning for increased rainfall despite having so many warnings. It is only going to get worse. We are completely in the know.”

She said the government must come up with a more coordinated ecosystem-based approach that extends beyond state boundaries, and conserves the soil and forests to act as sponges.

“A sponge city means greening up more spaces, having more gardens and harvesting rainwater.

“Look at where we can create sponges in Kuala Lumpur. Even in buildings, make sure the right type of grass is used and move away from concretising pavements.

“We need to look into how to do it in Kuala Lumpur because the city is so overdeveloped. It is not about building another Smart Tunnel. It is a challenge for urban planners.”

Pertubuhan Pelindung Khazanah Alam Malaysia president Shariffa Sabrina Syed Akil said Malaysia should learn how to mitigate floods from neighbour Singapore.

“It rains year-round in Malaysia. We must remember this whenever and whatever we build, but we never upgrade the drainage system. There are also not enough trees in the cities.

“Look at Singapore, it builds, but it also plants lots of trees. The government does not cover the lakes.

“It has reclaimed land, but what did it build? A forest, so it will absorb water when it rains.

“We build malls, condos and industrial areas. There is nowhere for water to go; all the lakes and water retention ponds are closed.

“So where do you expect the water to go?” – March 15, 2022.