SHAH ALAM, Oct 19 — Flood mitigation infrastructure upgrades in USJ, Subang Jaya, helped limit flash flooding to just 15 minutes on Saturday, despite extreme rainfall that closely resembled the conditions during a major flood in 2019.
Subang Jaya assemblyman Michelle Ng Mei Sze said the improved drainage system had helped prevent floodwaters from entering residents' homes while ensuring major roads remained passable to vehicles.
According to her, data from the Department of Irrigation and Drainage (DID) showed that the USJ 1 monitoring station recorded 113.5 millimetres (mm) of rainfall on Saturday, the highest in Selangor that day.
"While this represents clear progress, the fact that we did not experience a repeat of the 2019 floods does not mean the current situation is satisfactory.
"Residents deserve infrastructure that provides better protection against flooding, and we must continue working towards that goal," she said in a joint statement with Subang Jaya City Council (MBSJ) Zone 3 councillor Christopher Joseph today.
Saturday's heavy rainfall caused water levels in Sungai Klang and major drainage channels to rise, exceeding the downstream discharge capacity and triggering flash floods in low-lying areas around USJ 1, USJ 9 and USJ 12.
However, the RM756,100 on-site detention (OSD) facility at the junction of Persiaran Kewajipan and Persiaran Perpaduan operated at full capacity, supported by flow control structures and other retention ponds that helped minimise the impact of the flooding.
In response, Ng said several measures were being evaluated with the relevant authorities, including the installation of additional flow control structures, construction of new water detention facilities and a feasibility study on a drainage connection between USJ 13 and USJ 14 along Persiaran Mulia.
"Flood mitigation requires a coordinated approach that takes into account rainfall patterns, drainage capacity, water retention, downstream discharge and the evolving needs of the community," she said.
Ng and Joseph said the current focus was on finalising hydraulic data with DID and MBSJ, conducting water flow modelling and securing approvals to expand the drainage network.
For the record, extreme rainfall on October 17 triggered flash floods in several low-lying areas around USJ, but floodwaters receded within approximately 15 minutes without entering residents' homes.
In 2019, severe flooding along Persiaran Kewajipan left roads submerged for an extended period, with several vehicles seen floating in the floodwaters.
