YAN – The Minerals and Geoscience Department’s Geological Disaster Task Force has found no natural dams or blockages on the summit or slopes of Gunung Jerai that were said to have caused the water surge incident on August 18.
The department’s geological engineering branch head Ferdaus Ahmad said based on observation, there is nothing to show that a natural dam had formed from piles of wood and twigs, blocking water flow.
He said the water surge incident, also known as debris flow, was triggered by two factors: heavy rainfall on the day of the incident, and the area’s soil, rock and slope conditions.
“Prior to the incident, there was an extraordinary amount of rainfall, and rainwater seeped into the soil and softened its structure, as well as the rocks in the surrounding area.
“The slope gradient of more than 25°, apart from the cracks in the rocks, as well as the thickness of the soil on the surface of the mountain, were contributing factors to the landslide," he told reporters here today.
He said based on the triggers and contributing factors, the same disaster may recur in the Gunung Jerai area, but there is no telling exactly when.
On proposals for sabo dams, or check dams, to reduce the impact of water surges, Ferdaus said technical studies and similar methods implemented in other countries have shown that the structure can reduce the adverse effects of debris flow.
However, he said, the construction of these dams requires the involvement of various agencies, including the Works Department, Irrigation and Drainage Department, and National Hydraulic Research Institute of Malaysia to ensure their suitability for local use.
“We also need to consider geological factors in the area, whether such dams are suitable or cost-effective in reducing risks and preventing the loss of lives and property. Many factors have to be considered before making a decision.”
The Gunung Jerai disaster resulted in flash floods, claimed six lives, and affected about 800 homes in Yan and another 200 in Merbok, Kuala Muda. – Bernama, August 28, 2021
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