When PJ's flood sirens fell silent

 

Heavy rain triggered flash floods across parts of the Klang Valley today, disrupting traffic and leaving several vehicles stranded in rising waters, particularly in Petaling Jaya. - PIC CREDIT: SOCIAL MEDIA

Victims of last week's flash floods in Petaling Jaya are wondering if the perimeter rivers, the primary cause of the deluge, have minds of their own.

Flood sirens installed at Sungai Bakul, the Sungai Penchala corridor, the Sungai Subang and Sungai Buloh basins, the Shah Alam border zones and the Puchong and Southern Belts failed to activate on time.

Major parts of Petaling Jaya — Section 51, Section 51A, Kelana Jaya, parts of Damansara and the epicentre, Medan Selera 223 — were inundated, submerging vehicles and forcing the deployment of emergency response teams.

Residents uploaded videos and photographs of rising floodwaters on social media from Sections 13 and 17, Kota Damansara, Kampung Tunku and parts of Damansara Perdana.

Distressed traders and residents lamented the heavily blocked drains. One distraught widow lost two cars in two flash floods.

As river water levels rose, people went about their business seemingly unaware that alerts should have been activated.

Here is what should have happened: flood sirens activating when river levels, rainfall gauges and monitoring stations cross a threshold.

But if the water rises too fast, the siren system activation is delayed or may not cover all flood-prone areas while the blaring may not be audible to some residents.

Obviously, the system needs urgent review: did it malfunction or work too late to salvage property? Based on reports, extreme, rapid flooding may have exposed the sirens' limitations. In the 40-minute thunderstorm, a huge 60mm of rainfall forced back water that rushed from upstream Kuala Lumpur, causing the river channel to bust its banks.

Ironically, the Irrigation and Drainage Department's (DID) upgrading works to alleviate floods created artificial bottlenecks. Sungai Klang hit maximum capacity, preventing Sungai Penchala from draining out, resulting in severe backflow that pushed back water into Petaling Jaya's drainage systems. Sungai Damansara and its tributaries choked, compromising the drainage grid and curtailing surface water run-off.

From the heavens, an electric thunderstorm sent down a deluge surpassing drainage thresholds.

Due to intense urbanisation and sedimentation, waterways narrowed because of embankment repairs and clogged drains stifled water flow in affected areas.

Reduced natural water absorption and paved surfaces saw accumulated rainwater rush into low-lying flood-rone areas.

It is hoped that the sirens' ineffectiveness serves as a valuable lesson for local authorities and emergency responders to intensify flood monitoring, especially during huge thunderstorms. Still, it's a chicken and egg conundrum: to mitigate river failures, the Petaling Jaya City Council and DID are implementing long-term river overflow control systems, floodwalls and riverbank strengthening.

And yet, these ongoing works unfortunately contribute to Petaling Jaya's forever floods, as if life's permanent fixtures of death and taxes aren't bad enough. - NST