CITY councils have to increase their level of flood mitigation in line with global climate change demands, an engineer and environmentalist said.

He said it was crucial that storm water management be improved to reduce the impact of flooding.

Authorities should look into better drainage systems and build more retention ponds taking into account the effects of climate change, he said. 

Kolektif Iklim environmental activist Aidil Iman Aidid said Malaysia urgently needs to address the challenges of climate change.

He said this can be done through nature-based solutions, climate-smart education and early warning detection systems.

“Climate change is no longer a distant future issue. We are already living it.

“Extraordinary rainfall is fuelled by the climate crisis. However, the greatest blame should be placed on the failures of climate adaptation,” he told The Malaysian Insight.

Aidil was commenting on the flash floods that hit Kuala Lumpur and Selangor on Monday.

Environment and Water Minister Tuan Ibrahim Tuan Man had said that unusually heavy rain lasting two hours caused flash floods in the capital city.

He said the drainage system was unable to accommodate the high water capacity due to unusually heavy rainfall in Kuala Lumpur.

Ibrahim said that flood prevention projects in the city, including one at Sungai Bunus and another near the police training centre, are expected to be completed in 2024.

“We experienced a delay due to some issues with our previous contractor,” he said.

Environment and Water Ministry secretary-general Dr Zaini Ujang said the extraordinary rainfall recorded on Monday, which was almost equivalent to a month’s average, was the main cause behind the flash floods.

He said the average annual rain for the country was 2,500mm and the monthly national average was 208mm, adding that the rainfall recorded on Sunday at the Taman Desa SMART station was 106.5mm and at the Air Panas station it was 155mm.

Last year, heavy rainfall over the weekend of December 17-18 caused massive flooding in several states, including Selangor, Malacca, Negri Sembilan, Perak and Pahang.

The floods had displaced more than 70,000 people at its height and killed 54. Selangor was one of the worst-hit states.

Aidil said that climate change is the most apparent cause for the flooding in Kuala Lumpur and other areas.  

“The recent floods in KL was described as being half a month of rain within the span of two hours.

“Climate change makes extreme weather more intense and unpredictable.

“There are other factors like unsustainable land use as well as clogged drainage systems. What they have in common is that all these factors are human-induced.”

He said another issue was that drainage systems were clogged by rubbish because the country is overwhelmed with waste pollution, especially plastic.

“A common struggle for many Southeast Asia nations. This has been the prevalent cause for flash floods in KL.

“There needs to be greater awareness and accessibility to zero-waste lifestyles, as well as an extended Producer Responsibility Policy (EPR) to tackle this problem.”

Aidil said that on the bright side, the landmark move to mobilise a global treaty on plastic pollution at the United Nations proves that countries are taking the matter seriously.

As for massive development in the city centre, he said the bigger issue is whether these drainage systems can withstand the overwhelming effects of climate change and rubbish.

Upgrade flood resistance system

A former flood mitigation engineer, who declined to be named said the cause of recurrent floods in low lying areas with high rainfall was localised drainage systems that were insufficient.

As for extraordinary rainfall, he said, the existing flood resistance system is not sufficient to meet the demands upon it.

“If your existing flood resistance system cannot cater for extraordinary rainfall, you have to upgrade your flood resistance system.

“Identify hot spot areas and solve them first if budget is a constraint.

“Dumping waste into waterways like rivers and drains especially culverts will reduce their holding capacity and cause backflow that will cause flooding upstream.”

He said regular maintenance and cleaning of waterways especially before the expected rain period will help.

“The existing drainage system is not sufficient to cater for massive urban development.”

He said authorities should implement the Urban Storm Water Management policy under the Drainage and Irrigation Department.

This will hold rainfall runoff in on site detention ponds and allow water release when rainfall ceases.

“This will not cause water to overflow drains and cause flooding downstream.

“Implement it as a condition for urban development approval.”

He added that it is crucial to upgrade the flood resistance system to reduce the impact of floods.

“The councils should focus their efforts on hotspots. Include an early flood warning system, which helps to reduce flood impact.”

On climate change, he said that one of the reasons was heavy rainfall which could be the cause of the floods.  

“This is due to high rain density in a short duration. We cannot predict climate change.

“The issue of unprecedented rainfall which occurred last year in December is hard to predict.”

Another factor, he said is silting of rivers and the dumping of waste which clogs drainage systems.

“The people should change their attitude of dumping garbage carelessly.

“Flooding in the city centre produces a bad image of the country.” – March 9, 2022.