PUTRAJAYA: Flash floods which hit several key roads in the Klang Valley yesterday evening was caused by an inefficient culvert system. Natural Resources and Environment Minister Datuk Seri Wan Junaidi Tuanku Jaafar said the flash floods which occurred at Jalan Duta, Universiti Malaya and Bangsar were caused by high volume of rainfall within two hours in the affected areas. "Inefficient culvert system and heavy rains caused the flash floods. The culverts couldn't support the high volume of water causing it to overflow. Sungai Klang did not overflow, checks show that it was one meter below its full capacity. "The drainage system in the city must be re-looked since the flash floods happened without the river reaching its full capacity," he told the media at a press conference in his office today. He also clarified that there were no issues with the Smart tunnel. "It is not that the Smart tunnel isn't working, it didn't rain near the Smart tunnel," he said. Wan Junaidi said a detailed study needs to be done together with Kuala Lumpur City Hall and the Department of Drainage and Irrigation to come up with a long term and short term plan to tackle the flash flood problem. "In my opinion it seems that La Nina is here early. We expected heavy rain in June and already had plans for culvert maintenance. But the heavy rain is happening now, two weeks earlier. But the dams at the northern states are still dry. This is a worrying weather pattern. "We need to study and come up with plans to handle this weather condition," he said, adding that development in the city area also aggravated the problem. "Developers should share the responsibility. They should not work against nature, as it can cause harm." Meanwhile, a Fire and Rescue department spokesperson told theSun that the poor drainage system in Jalan Semantan and Jalan Lingkungan Budi was the main cause of yesterday's flash floods. "Our investigation revealed that the drainage system at both areas could not cope with the capacity of rainwater yesterday evening," he said when contacted. He added that the flash floods in Jalan Semantan was worse due to an ongoing construction around the area.