An inefficient and outdated flood mitigation system coupled with unchecked development and poor drainage led to the massive floods in the Klang Valley and Pahang recently, experts say.
Despite the red alert issued by the Meteorological Department on heavy rainfall in Selangor, Kuala Lumpur and Pahang, not much could have been done due to the lack of infrastructure.
While the magnitude of rainfall could not be controlled, experts said the floods would not have been as severe had there been proper drainage and sufficient flood mitigation facilities.
They said the severity of the floods varied based on the geographical landscape and infrastructure of affected areas.
Association of Water and Energy Research Malaysia president S. Piarapakaran said Taman Sri Muda in Shah Alam and parts of Klang and Kuala Selangor were on flat land, or a delta, where wa-ter and sediment from rivers ga-thered before flowing to the sea.
“Water moves from higher to lower ground. But in between, it will flow slowly towards freshwater swamps that serve as natural buffers before it reaches the sea.
“But during heavy rain, there is an increase in velocity, causing water from Sungai Klang to overflow into a nearby area, like what happened in Taman Sri Muda.”
He said the flood mitigation system of drains and flood retention ponds could not handle the high volume of water that came with the downpour, which posed a larger question of actual capacity when new development projects are started in an area.
He said any mitigation project would involve calculating the estimated amount of water gathered in worst-case scenarios based on existing development.
“With the change of land use and new developments added to the mix, for instance, a higher volume of water is expected. The mitigation system will be overloaded and will fail when this happens.”
Piarapakaran said the Hulu Langat area is around the Sungai Langat river basin, where it is supported by smaller rivers.
He highlighted overdevelopment in forested areas.
Due to the lack of natural buffer zones, a downpour would cause the water to flow fast, creating a high level of energy called a hydraulic jump.
“The river is holding so much water that it gushes out to any area it can access as the hills have been cleared,” he said.
To compound matters, upgrading of the drainage and irrigation system was done only in some areas, which would not cover the whole system.
He said it was unbecoming of leaders to blame the bad weather and the public for being unprepared to face the floods.
“It is the responsibility of the authorities to ensure a proper mitigation system.
“The government had 12 hours to run a simulation exercise based on real-time information as we were experiencing the downpour. Even a warning an hour ahead could have saved a lot of things.
“There is a need to restructure facilities, like telecommunications and electricity and water supply.”
Supporting facilities like roads and government buildings also need to be reviewed to reduce the impact of floods.
Environmental health expert Professor Dr Jamal Hisham Hashim said the government should take a closer look at the root cause of the floods that were triggered by downpours and compounded by overdevelopment, outdated and insufficient drainage systems and the lack of flood mitigation measures.
“We are still in a reactive mode in flood disaster response and
recovery when we should have scaled up to proactive flood mitigation and preparedness mode.
“Only when all areas are addressed will our flood disaster management plan be complete and comprehensive. We have to take the element of surprise out of disaster by preparing for the worst,” he said.