Monday February 4, 2013
Predicting future landslides
By P. ARUNA
PETALING JAYA: Work has begun on an early warning system that can send out alerts at least two hours before a landslide occurs.
People living in landslide-prone areas will be warned via TV and radio, enabling quicker evacuation.
The Public Works Department (PWD) is in the process of creating the system, similar to the high-tech model used in landslide-prone Hong Kong.
The PWD had already conducted pilot studies at two “hot spots” Bukit Antarabangsa, Selangor and the Tapah-Cameron Highlands road.
“We are targeting 90% accuracy so it requires a lot of data on rainfall patterns and intensity in the vulnerable areas,” said PWD's slope engineering unit head Dr Che Hassandi Abdullah.
The PWD's Landslide Warning System (LWS) is currently being tested at Bukit Antarabangsa.
He said the department's challenge was to ensure it was accurate enough to prevent false alarms.
“We don't want to end up crying wolf too many times. No one would take the alerts seriously after the first few false calls,” he said.
The LWS is being designed to provide warnings at least two hours ahead, compared with the three-hour benchmark set by Hong Kong.
The department has identified 21,000 landslide-prone areas throughout the country out of which 16,000 or 76% are in peninsular Malaysia while about 3,000 are in Sabah and 2,000 in Sarawak.
Based on the huge amount of data needed to ensure precision, full implementation could take up to five years.
Dr Hassandi said data from the Malaysian Meteorological Department and the Drainage and Irrigation Department would be analysed with the patterns of rainfall and intensity that had triggered previous landslides.
The PWD would use mobile and satellite communications to transmit data from the monitored areas to the central monitoring system managed by its slope engineering division.
Dr Hassandi said the National Security Council (NSC) had agreed to allow the alerts to be broadcast over television and radio, if the warning system proved to be accurate.
“We would also put up signboards to warn people not to use roads in landslide-hit areas. If is a major landslide, the NSC would decide whether residents should be evacuated,” he said.
He said landslides occurred during or immediately after rain, adding that most were in rural areas, with the exception of Ampang Jaya in Selangor.
“Rainfall does not cause landslides but triggers them on slopes that are unsafe or dangerous,” he said.
He said major landslides were easier to predict than minor ones because there would be warning signs such as widening cracks on structures in or outside homes or concentrated amounts of water overflowing onto slopes.
“But minor landslides can be equally dangerous, as when a car passing by at the time could be buried or pushed over a cliff,” he said.
Besides the LWS, research funded through Universiti Sains Malaysia (USM) by the Japanese government is also being conducted on hillslopes in Jeli, Kelantan, Kenyir, Terengganu, the Kelantan river basin and the East-West Highway to monitor earth movements and floods.
The data collected would be used for the development of site-specific geo-hazard early warning systems.
“We are working with USM researchers by providing advice and information on critical sites to place instruments,” Dr Hassandi said, adding that the department was certain that it could use the data from the research.