KUALA LUMPUR: If the Smart Tunnel had not been activated to its full capacity yesterday, an area covering 15ha in the city centre -- the size of 20 football fields -- could have been underwater.
Department of Irrigation and Drainage director-general Datuk Nor Hisham Mohd Ghazali said this while coming to the defence of the Stormwater Management And Road Tunnel (SMART Tunnel) system, adding 3 million cubic metre of water that could have inundated a 1km radius from Masjid Jamek, was diverted in time.
He said this was the 7th time in history that the system had activated its 4th mode, where the entire tunnel regularly used for traffic diversion, morphed into a storm diversion and retention mechanism.
"The system functioned as required and complied with all SOPs related to floodwater diversion," he said, adding the system's control centre began the diversion of the Klang River at 2.50pm.
Nor Hisham was referring to the backlash received by the department and Smart Tunnel for what was perceived as a delay in the response of the state of the art system.
He said all 6 retention ponds on the Klang and Gombak river circuits were operating at full capacity by storing a whopping 12.2 million cubic metre of water, and said no water was released from the facilities which were operating at full capacity.
"People misconstrued (the situation) by claiming that the system was idling, because traffic was still allowed to pass before we activated mode 4 at 4.40pm."
Nor Hisham said another misconception was that the system had diverted water from the Klang and Gombak rivers, although it only actually diverted water from the Klang River.
One of the reasons for the unexpected floods, he said, was due to the existing drainage systems that could not support the large volumes of surface runoff.
"While 13 stations in the city recorded rainfall of more than 100mm each, at Simpang 3, Gombak the reading was more than 200mm in around five hours," he said, confirming earlier reports that floodwaters were up to 0.9 metres in hotspots.
Nor Hisham also agreed with the Malaysian Meteorological Department's peak rainfall readings of 44.5mm at 4pm, stressing that the highest rainfall was recorded upstream at the rivers' catchments.
He also said only Sungai Bunus near the National Library around Jalan Tun Perak bridge overflowed for around 15 minutes.
Nor Hisham said among the possible factors for the flash floods in the city was overdevelopment and the city's drainage having operated beyond capacity, but more investigation needed to be done on the recent flooding.
He said planning guidelines stipulated that developers needed to have their own water retention facilities to control large scale development.
"We also included requirements to ensure that the river flows at the same capacity before and after development, but we feel that this needs better enforcement," he said.
Nor Hisham also said these guidelines would soon come under review and hoped local authorities would adopt them in their centres for planning permission.
Referring to photos circulating on the social media on yesterday's floods, he said: "From the photos, we can tell that the water is reddish and not clear. If the water is red in the drains, it could have come from exposed earth, from surface run off from construction sites and sediment."
He said under the Flood Mitigation Plan, there were some projects that needed to be completed. They include packages within the Sungai Bunus flood mitigation project which is in the building stage, adding City Hall had to review its drainage system.
There was also a need for more flood retention facilities, he said, urging the government to consider underwater systems for Kuala Lumpur by following the Japan model to address the lack to physical space to do so.
"Surplus land owned by the government can be used as reservoirs, to be processed as drinking water if the need arises.
And space in recreational parks can be used for surface-level reservoirs."
"What is worrying is the state of rivers in KL and its borders. There is no way we can deepen or widen our rivers and waterways due to development. Our space is limited and development has to be guided towards more sustainable concepts."
Meanwhile, Nor Hisham also said that DID status report on the flood has been sent to Environment and Water Minister Datuk Seri Tuan Ibrahim Tuan Man.
Federal Territories Minister Tan Sri Annuar Musa said his officers would study the cause of severe flash flooding which struck the capital yesterday, and find a long-term solution to prevent crippling inundations from recurring.
He said it would request a report from the Irrigation and Drainage Department (JPS) and Kuala Lumpur City Hall (DBKL) on the capabilities of existing irrigation and flood mitigation systems, including the Smart Tunnel.
He said the ministry will also explore whether ongoing developments in several locations in the city have exacerbated the situation.
Heavy rain which lashed the Klang Valley from 1.30pm caused flooding across the capital, with the five worst-hit areas being Lebuh Ampang, Jalan Raja Alang (Kampung Baru), Lorong Air Leleh (Setapak), Jalan Gurney and Jalan San Ah Wing (Semarak). Water rose to as high as 3m in some areas.