For residents of scenic Bertam Valley, the sirens which came soon before the flood hit was probably the first hint they got that they were living in the path of disaster.
But for researchers studying the Ringlet Reservoir, where the Sultan Abu Bakar Dam is located, the sirens have been blaring for at least a decade before disaster struck.
Going by the papers published as early as 1997, Oct 23's tragedy was a human-made calamity - a combination of the failure to control forest clearing and to keep population off the river banks.
And it is not only illegal farms and squatters who are settling near the river - a 2011 simulation, ironically by TNB's own Universiti Tenaga Nasional (Uniten), showed that a school and a surau were in harm's way.
Indeed a post-flood photograph taken on Oct 23 showed a school compound in Bertam Valley covered in mud.
Similarly, three years before the disaster hit, a Universiti Kebangsaan Malaysia research published in an international journal warned that 3,000 Bertam Valley residents were in danger in event of heavy rain.
Massive forest clearing
Meanwhile, Universiti Malaya researchers said in a paper published in 1997 that massive forest clearing caused siltation, which compromised the reservoir's flood mitigation functions.
The same red flag was raised in a paper by a TNB subsidiary published by a Japanese institute close to a decade later.
"Extensive reforestation and indiscriminate earth bulldozing in the Cameron Highlands area for agricultural and housing development has resulted in widespread soil erosion over the land surface," the TNB Hidro Sdn Bhd study reads.
The study noted that the sediment load in Sungai Telom and Sungai Bertam, which flows into the Ringlet Reservoir, has increased 20-fold and 17-fold respectively since the 1960s.
Forty years since its completion in 1963, siltation has reduced the dam's capacity to about half, when it was supposed to last for 80 years.
Uniten researchers stressed that their simulation shows flood in Bertam Valley due to reservoir release is a "very real situation".
"Results from the scenarios tested indicated that the population downstream is at risk if such a release occurs," they said in the paper published in the Journal of Flood Engineering last January.
Five metres under water
The research team, including a TNB senior engineer, added that even if a "small discharge" of 4m³ per second is released from the dam, downstream structures will be at "high risk of flooding" with flood waters expected to be about a metre deep.
If one flood gate was lifted, as was the case in the Oct 23 disaster, the downstream areas - including a surau and a school - will be hit by flood waters 5 to 6m deep.
On Oct 23, the one gate was lifted thrice, causing massive damage to property and the loss of four lives.
The researchers noted that stuctures were in harm's way despite the dam already marked as having a "high downstream hazard" upon its completion in 1963.
"The original river reserve downstream at Sungai Bertam was gazetted in 1996 at 60m from each bank providing at least total river flood flows at 130-150m.
"Present field inspection reveals that a certain location of only having 2-3m of river width," they said.
TNB CEO Azman Mohd in a press release Monday admits that people living on the riverbanks is problematic.
He also agrees that the siltation, which has been decades in the making, is posing an increasingly greater threat to lives.
Move out or risk going under
To an extent TNB's mitigation works have been successful - its dredging works and weir construction has averted doom situation predicted by researchers in the 1990s.
Researchers had predicted that the reservoir will be at full capacity by the year 2000, but with mitigation, there is still about 50 percent capacity by 2013.
The 50 percent capacity, however, was not enough to hold rainwater build-up last week, where rainfall was triple the expected levels.
Azman said that with weather issues and heightened development activities, the situation is even harder to predict and those living beside the river should move out.
"The people living in the area are still not out of the woods yet as development activities that have caused Bertam reservoir to lose its water holding capacity continue to gain momentum.
"We don't think anybody can guarantee the safety of the people at the site given the present conditions. Thus they should be kept out of harm's way and vacate the area," he added.
Going by the papers published as early as 1997, Oct 23's tragedy was a human-made calamity - a combination of the failure to control forest clearing and to keep population off the river banks.
And it is not only illegal farms and squatters who are settling near the river - a 2011 simulation, ironically by TNB's own Universiti Tenaga Nasional (Uniten), showed that a school and a surau were in harm's way.Indeed a post-flood photograph taken on Oct 23 showed a school compound in Bertam Valley covered in mud.
Similarly, three years before the disaster hit, a Universiti Kebangsaan Malaysia research published in an international journal warned that 3,000 Bertam Valley residents were in danger in event of heavy rain.
Massive forest clearing
Meanwhile, Universiti Malaya researchers said in a paper published in 1997 that massive forest clearing caused siltation, which compromised the reservoir's flood mitigation functions.
The same red flag was raised in a paper by a TNB subsidiary published by a Japanese institute close to a decade later."Extensive reforestation and indiscriminate earth bulldozing in the Cameron Highlands area for agricultural and housing development has resulted in widespread soil erosion over the land surface," the TNB Hidro Sdn Bhd study reads.
The study noted that the sediment load in Sungai Telom and Sungai Bertam, which flows into the Ringlet Reservoir, has increased 20-fold and 17-fold respectively since the 1960s.
Forty years since its completion in 1963, siltation has reduced the dam's capacity to about half, when it was supposed to last for 80 years.
Uniten researchers stressed that their simulation shows flood in Bertam Valley due to reservoir release is a "very real situation".
"Results from the scenarios tested indicated that the population downstream is at risk if such a release occurs," they said in the paper published in the Journal of Flood Engineering last January.
Five metres under water
The research team, including a TNB senior engineer, added that even if a "small discharge" of 4m³ per second is released from the dam, downstream structures will be at "high risk of flooding" with flood waters expected to be about a metre deep.
If one flood gate was lifted, as was the case in the Oct 23 disaster, the downstream areas - including a surau and a school - will be hit by flood waters 5 to 6m deep.On Oct 23, the one gate was lifted thrice, causing massive damage to property and the loss of four lives.
The researchers noted that stuctures were in harm's way despite the dam already marked as having a "high downstream hazard" upon its completion in 1963.
"The original river reserve downstream at Sungai Bertam was gazetted in 1996 at 60m from each bank providing at least total river flood flows at 130-150m.
"Present field inspection reveals that a certain location of only having 2-3m of river width," they said.
TNB CEO Azman Mohd in a press release Monday admits that people living on the riverbanks is problematic.
He also agrees that the siltation, which has been decades in the making, is posing an increasingly greater threat to lives.
Move out or risk going under
To an extent TNB's mitigation works have been successful - its dredging works and weir construction has averted doom situation predicted by researchers in the 1990s.
Researchers had predicted that the reservoir will be at full capacity by the year 2000, but with mitigation, there is still about 50 percent capacity by 2013.
The 50 percent capacity, however, was not enough to hold rainwater build-up last week, where rainfall was triple the expected levels.Azman said that with weather issues and heightened development activities, the situation is even harder to predict and those living beside the river should move out.
"The people living in the area are still not out of the woods yet as development activities that have caused Bertam reservoir to lose its water holding capacity continue to gain momentum.
"We don't think anybody can guarantee the safety of the people at the site given the present conditions. Thus they should be kept out of harm's way and vacate the area," he added.
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