Kedah floods caused by debris flow, not water surge, says expert
ALOR SETAR: The incident in the Gunung Jerai area that resulted in mudslides and floods on Wednesday was not caused by a “water surge” phenomenon, but due to debris flow, which is a common occurrence in mountainous areas, says an expert.
Ibrahim Komoo, the principal research fellow at the Institute for Environment and Development (Lestari) in Universiti Kebangsaan Malaysia (UKM), said a debris flow was a more accurate description for the incident due to the abnormally heavy rainfall in the area.
He said water surges occur when an unusually high volume of rainfall flows into the riverbeds which are interrupted due to sediments and debris, causing the water level to go up several metres.
“Meanwhile, a debris flow forms when water brings soil and forest debris rapidly downwards, to the foothill,” he said.
On Wednesday, the area around Gunung Jerai was hit by mudslides and landslides due to a sudden rush of water which resulted in four deaths with two victims still missing.
The disaster caused damage to properties and facilities and affected residents in the towns nearby.
Ibrahim said the incident would not recur anytime soon as the area has now been cleared of debris such as fallen trees and there would now be an uninterrupted flow of rain water.
He said a similar incident had happened before in Pos Dipang, Perak in 1996 which destroyed an Orang Asli village and killed 44 people.
“An almost similar incident happened at Genting Sempah in 1995 that killed many people.”
He added that it was a natural phenomenon and had nothing to do with logging activities.
Environmental hydrologist and river modelling expert Mohd Ekhwan Toriman said satellite images did not detect any logging or large-scale agricultural activities in the Gunung Jerai area.
He said water surges due to rainfall would bring with them wood debris, stones and silts which would cause mud floods up to 1.5 metres deep at the foothills.
He speculated that the Gunung Jerai incident was probably caused by debris that had accumulated and formed a dam in the upper reaches of the river, adding that abnormally heavy rainfall collected more debris and became stuck in the natural dam.
“High pressure probably caused the dam to break, bringing with it debris, rocks, wood debris, sediments and silt,” he said.
He said rainfall distribution at the rainfall stations in Gunung Jerai and Kampung Singkir Genting recorded 218mm and 172mm of rainwater during the incident.
Meanwhile, Institute of Geology Malaysia (IGM) president Abd Rasid Jaapar said a complete and independent geology disaster study should be carried out in Gunung Jerai and the surrounding area.
In a related development, police said the third day of the search and rescue operation for the two people reported missing in Wednesday’s massive floods in Yan ended without any success.
Yan district police chief Shahnaz Akhtar Haji said today’s operation was still concentrated in two locations, namely Titi Hayun and Batu Hampar, where both victims were reported missing.
“We added a team comprising 308 members from various agencies and used drones from the police and the fire and rescue department to locate the victims.
“However, when the operation ended at 4pm, there was still no indication of the whereabouts of the victims. We will resume the search operation at 8am tomorrow,” he said.
He said the operation had also been expanded to cover nearby waters based on the discovery of the fourth victim’s body at the mouth of Sungai Udang yesterday.
However, he explained that the search operation encountered some difficulties as the location included rocky and muddy terrain.
“We will increase the strength of the team and also seek the assistance of the police air unit,” he said. - FMT
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