ISKANDAR PUTERI: Damaged underground culverts and ageing drainage infrastructure have been identified as key factors behind recurring flash floods along Jalan Ceria, with Monday’s downpour exposing weaknesses in the drainage network.
The 62mm rainfall overwhelmed the system, while a blocked and damaged underground crossing culvert further restricted water flow, causing runoff to accumulate along the low-lying road.
State Housing and Local Government Committee chairman Datuk Mohd Jafni Md Shukor said investigations found that utility-related contractor works had damaged an existing crossing culvert, disrupting water flow and contributing to the flooding.
He said the drainage system was also struggling to cope with increasingly heavy rainfall, with current downpours estimated to be three to four times higher than the usual 10mm to 20mm.
“The existing drainage infrastructure is no longer adequate to cope with the volume of water.
“Simply enlarging the road drainage openings is only a small part of the solution. We need to look at the entire drainage system,” he told the New Straits Times.
Earlier, he inspected the flood-prone area with Iskandar Puteri City Council (MBIP) officials.
Jafni said three parties had been tasked with addressing the problem.
Tenaga Nasional Bhd (TNB) will repair the damaged underground crossing culvert, which its investigations found had disrupted water flow.
MBIP will oversee the cleaning and maintenance of the retention pond, which was heavily overgrown with trees and bushes, while its concessionaire, Safwa Global Ventures (M) Sdn Bhd, will carry out drainage improvement works.
These will include cleaning the twin box culvert, installing additional scupper drains to speed up water discharge and deepening the existing earth drain.
The earth drain will be enlarged to between 80 and 100 feet long, 15 and 20 feet wide, and seven and eight feet deep. The overall improvement works are estimated to cost more than RM500,000.
Jafni said the immediate works were expected to be completed within two weeks, subject to weather conditions.
He also directed the MBIP and the Public Works Department to study the possibility of enlarging road drainage openings to improve water discharge.
However, he said, such measures alone would not address the underlying problem unless the entire drainage network was upgraded.
Longer-term proposals include building a 1.77-acre retention pond near Taman Sireh, upgrading an existing two-acre retention pond and raising part of Jalan Ceria, at an estimated cost of RM4 million.
Jafni said drainage requirements and development specifications also needed to be reviewed at federal and local authority levels to ensure new developments could cope with heavier rainfall.
He said developers should be required to adopt stricter drainage specifications, while existing infrastructure needed to be upgraded to reflect changing rainfall patterns.