KUALA LUMPUR needs a holistic flood mitigation solution for the northwestern side of the capital, as the existing SMART tunnel serves to divert floodwater from a limited area, tunnel operator SMART Highway said today.

It said the March 7 flash floods in the city where Kuchai Lama and Jalan Klang Lama were among the worst hit, were areas not within the SMART Tunnel’s flood alleviation coverage.

“The badly hit areas in Kuala Lumpur on March 7 suffered from two contributing factors, insufficient carrying capacity from rivers particularly Sungai Kerayong, Sungai Bunus and Sungai Kuyoh, which are outside of the SMART Tunnel flood alleviation zone, and intense rain overwhelming the local drainage networks in these areas,” the company said.

The company shared a map (See above) showing the tunnel’s coverage area and areas where flash floods occurred that are outside the tunnel’s service area. 

SMART, which stands for Stormwater Management and Road Tunnel, mitigates floods along the Klang river that pass through the Kuala Lumpur city centre. These areas include Dataran Merdeka.

Kuchai Lama and Jalan Klang Lama, however, lie further downstream from the city centre and away from the tunnel’s coverage zone.

“The intense rainfall recorded on the evening of March 7 was described by Environment and Water Minister Tuan Ibrahim Tun Man as half a month’s average rainfall in two hours’. 

“This level of rainfall equates to exceeding a ‘once-in-100-year’ event in some areas such as the Sungai Kerayong catchment, resulting in damaging flash floods in Kuchai Lama and Jalan Klang Lama,” the company said.

It also noted that flooding around the Masjid Jamek area, where the Gombak and Klang rivers meet, had come primarily from the Gombak, Keroh and Batu rivers upstream, more than from the Klang river.

The company calls for a holistic flood mitigation solution to cover the parts of Kuala Lumpur that lie within the catchments which are not served by the SMART Tunnel.

“Given the advent of climate change, increased frequency of extreme weather events is forthcoming. Therefore a holistic flood mitigation solution targeting the northwestern side of Kuala Lumpur within the catchments of Sungai Gombak and Sungai Bunus will need to be expedited. A robust maintenance regime is needed for our local drainage networks to minimise the future impact of these extreme weather events in Kuala Lumpur.”

During Monday’s floods, the company said the SMART Tunnel was activated at 2.30pm, progressing from one mode of operation to the next anticipating rising water levels and flow rates.

However, it never had to activate Mode 4 which involves complete tunnel closure to traffic for flood water diversion, as rain intensity subsided and water levels at the Klang river did not spill over. The tunnel was reopened to traffic at 10pm.

The company’s call for a holistic flood management plan for the capital echoes similar suggestions made by MPs in Parliament yesterday. 

Federal Territories Minister Shahidan Kassim said that Kuala Lumpur City Hall was in the process of engaging a consultant to redesign the city’s drainage system. – Bernama, March 10, 2022.