YAN: The Geological Disaster Task Force of the Minerals and Geosciences Department have found no natural dams or blockages on the summit or slopes of Gunung Jerai that were said to have caused the Aug 18 water surge incident.

       However, they warned it may happen again.

       Its Geological Engineering Branch head Dr Ferdaus Ahmad said based on observation, there was no evidence to show that a natural dam had been formed from piles of wood and twigs that blocked water flow.

       He said the water surge incident, or in geological terms known as debris flow, was triggered by two factors: heavy rainfall on the day of the incident and soil, rock and slope conditions in the area.

       “Before the incident happened, 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 degrees, apart from the cracks in rocks, as well as soil thickness on the surface of the mountain, were contributing factors for the landslide,” he told reporters here yesterday.

       He said based on the combination of trigger and contributing factors, the same disaster could recur in the Gunung Jerai area.

       However, the department could not predict when exactly.

       Commenting on proposals for a sabo dam (check dam) on slopes and rivers in the area to reduce the impact of water surges, Ferdaus said based on technical studies and similar methods adopted in other countries, such dams could reduce the adverse effects of debris flow.

       However, he said the construction of these dams would need the involvement of various technical departments.

       The departments include the Works, Irrigation and Drainage as well as the National Hydraulic Research Institute of Malaysia.

       This is to ensure the method was suitable and effective for local use.

       “We also need to consider geological factors in the area,” said Ferdaus.

       “We need to consider whether such dams are suitable or cost-effective in reducing risk and preventing loss of lives and property.

       “Many factors would have to be considered before making the right decision,” he said.

       The water surge incident on Aug 18, which resulted in flash floods, claimed six lives and affected about 800 homes in Yan and another 200 more in Merbok, Kuala Muda. — Bernama