The nation was in shock when pictures emerged last week of Taman Sri Muda swallowed by water as deep as 4m in some areas.
Those with a second storey were lucky, as at least half of their homes was left intact, but others in single-storey buildings were not so fortunate.
How did it get so bad?
FMT spoke to members of the residents association for Zone D, who have done research and mapping of the drainage system, to find out.
The first major flooding in the low-lying Taman Sri Muda township occurred in December 1995. Then, the water reached up to slightly higher than 1m.
In response, the state government undertook extensive flood mitigation measures. A retention pond was built nearby, and a network of drains and irrigation canals was built to divert rain water into the Klang River.
This was sufficient for over 20 years, with only minor flooding occurring from time to time owing to the area’s low-lying position.
How does it work?
Taman Sri Muda’s drainage system is not dissimilar to most.
There is a network of drains like you would see in any housing area, that collects water from houses and the streets. The drains flow into even larger drains which then connect to a series of irrigation canals that border the township. These are like miniature rivers.
From these canals, the water either flows directly into the Klang River via a tidal gate, or into a retention pond, which stores water until a more suitable time to be pumped into the river.
When the tide in the Klang River is higher than the water level in the canals, water is diverted into the ponds. Opening the gate during high tide would allow water into Taman Sri Muda, which would be counterproductive. When the tide is low, the canals can feed water directly into the river through the opened gate.
What went wrong?
The system is not broken. It is overloaded.
As years went by and the surrounding Kota Kemuning area was developed, new projects opted to piggyback on the existing drainage system in Taman Sri Muda to divert rainfall into the river, rather than build new networks.
Members of the residents association say they have traced drains leading to the irrigation canal from Kemuning Utara, Kemuning Baru, Kota Kemuning and other upstream areas.
This means the system, designed to cater to Taman Sri Muda, now has to deal with the water from much of the surrounding areas which, residents estimate, at least triples the volume it was designed to handle.
This is manageable during normal times for the most part, but everything overflows when rainfall is heavy. The irrigation canals, drains and the retention pond all quickly fill up as they are inundated with water, which spills over into the township.
While there are pumps installed to bypass the tidal gate and force water into the Klang River, these can only deal with so much water. Again, these were put in place to deal with Taman Sri Muda’s water, not everyone else’s.
Taman Sri Muda has essentially become one giant retention pond for the area.
What has happened?
Since 2019, there have been multiple floods every year. The water level regularly reaches residents’ knees, but they have grown to live with the floods.
However, the system was stressed beyond its capability in the middle of this month when historic rainfall left much of Taman Sri Muda submerged for days.
When the authorities tried to open the tidal gate to pump out the excess water into the Klang River, they realised one of the pumps was broken, compounding matters.
What is happening?
An allocation of RM10 million had been set aside in 2020 to upgrade the pumps at the tidal gate, but the work has yet to be done.
Kota Kemuning assemblyman V Ganabatirau lamented last week that he had been pushing the department of irrigation and drainage to repair the pumps months ago to no avail.
“If only the pumps had been fixed earlier,” he told FMT, questioning the delays. “What happens next is anyone’s guess. Residents have been calling for action since 2019, but little has been done.
“Now, inhabitants of the area are paying the price for this inaction and the poor planning of the surrounding area.”