FMT:
Compile every detail of slopes to cut risk of landslides, HK expert tells Penang
3 hours ago
Predeep Nambiar
Public engagement, grassroots participation also essential to ensure safety, says geotech specialist
Every piece of information on slopes can help to reduce the risk of landslides and ensure safety, says Hong Kong geotech expert Raymond Cheung. (JBPM pic)
GEORGE TOWN: A database of all hillslopes, including how man-made ones were built, is essential to reduce the risk of landslides occurring, according to a geotechnical expert.
Over and above that, there must be a system to issue warnings of bad weather early to alert the public to potential risks, Raymond Cheung, who heads Hong Kong’s Geotechnical Engineering Office, told FMT.
Over and above that, there must be a system to issue warnings of bad weather early to alert the public to potential risks, Raymond Cheung, who heads Hong Kong’s Geotechnical Engineering Office, told FMT.
Raymond Cheung.
These steps should also go hand-in-hand with public engagement to build trust and a sense of responsibility at the grassroots level, he added.
Citing Hong Kong’s strong track record in reducing the incidence of landslides, Cheung said there must be political commitment and a single agency clearly in charge of slope safety.
He said that for Penang, the first step the authorities must take is to build a detailed record of all slopes covering their locations.
“In the case of man-made slopes, we must know how they had been built, if there had been issues in the past, and what lies beneath these slopes,” he said.
“With a proper catalogue, we can understand the magnitude of the problem and focus on the riskiest ones first,” he added.
Cheung recalled that Hong Kong took steps to reform its system after two deadly disasters in the 1970s. In June 1972, a series of landslides wiped out several apartment blocks and houses and left 156 people dead.
In August 1976, water-logged mud poured into the lower floors of an apartment block, killing 18 people.
Cheung pointed out that rainfall is the quickest and most common trigger for landslides.
He said Hong Kong started with only a handful of rain gauges decades ago, but it now has more than 120 placed in stragetic sites and are constantly monitored.
He said the 136 rain gauges now in place in Penang must all be linked to a proper alert system.
Cheung said that in Hong Kong, each gauge feeds data into a central platform that is linked to the slope database. “When rainfall exceeds a certain level, especially over 24 hours, public warnings are issued,” he added.
According to Penang’s hill site guideline, almost 40% of land on the island has very steep slopes of more than 25 degrees. In comparison, only about 5% of the mainland has slopes steeper than 15 degrees.
For most people, walking up a 25-degree slope is like a strenuous exercise.
Earlier this month, the state assembly was told that Penang saw 20 road collapses and 68 landslides this year, more than double compared with last year. All the landslides were on the island, with most occurring in the northeast and southwest districts.
Heavy rain has also pushed the Air Itam dam to 99.4% capacity, its highest level since 2021, after more than 500mm of rainfall in its catchment area in just two months.
State officials said the continuous rain has softened soil and aggravated leaks in ageing underground pipes, leading to road cave-ins.
To improve detection of such occurrences, Penang Island City Council has bought a ground penetrating radar system, while the public works department has received RM8.79 million to repair and reinforce 16 high-risk slopes.
Public trust just as crucial
Cheung said rather than emulate Hong Kong’s strategy right away, Penang should start small and build from there.
He also said clear communication is crucial to build public confidence in the system.
“Hong Kong backs its engineering work with public education campaigns, guides for homeowners and regular updates during heavy rain,” he said.
He also stressed the importance of assigning an “owner” or caretaker for every made-made slope, be it a government body, a private business or a homeowner.
“In Hong Kong, we know who is responsible for every slope. That makes follow-up action easier,” he said, adding that such information should be publicised to prevent confusion when problems arise.
This is especially relevant in Penang, where many slopes are close to housing estates or border public infrastructure, making it unclear as to who should inspect or repair them.
Cheung said early warning systems only work if people trust in and act on them, built over years of transparency and community education.
“We do not need to have a perfect system to start protecting people. A simple rainfall-threshold based warning system and clear assignment of responsibilities, together with transparent communication to the public, can already make a big difference,” he added.
These steps should also go hand-in-hand with public engagement to build trust and a sense of responsibility at the grassroots level, he added.
Citing Hong Kong’s strong track record in reducing the incidence of landslides, Cheung said there must be political commitment and a single agency clearly in charge of slope safety.
He said that for Penang, the first step the authorities must take is to build a detailed record of all slopes covering their locations.
“In the case of man-made slopes, we must know how they had been built, if there had been issues in the past, and what lies beneath these slopes,” he said.
“With a proper catalogue, we can understand the magnitude of the problem and focus on the riskiest ones first,” he added.
Cheung recalled that Hong Kong took steps to reform its system after two deadly disasters in the 1970s. In June 1972, a series of landslides wiped out several apartment blocks and houses and left 156 people dead.
In August 1976, water-logged mud poured into the lower floors of an apartment block, killing 18 people.
Cheung pointed out that rainfall is the quickest and most common trigger for landslides.
He said Hong Kong started with only a handful of rain gauges decades ago, but it now has more than 120 placed in stragetic sites and are constantly monitored.
He said the 136 rain gauges now in place in Penang must all be linked to a proper alert system.
Cheung said that in Hong Kong, each gauge feeds data into a central platform that is linked to the slope database. “When rainfall exceeds a certain level, especially over 24 hours, public warnings are issued,” he added.
According to Penang’s hill site guideline, almost 40% of land on the island has very steep slopes of more than 25 degrees. In comparison, only about 5% of the mainland has slopes steeper than 15 degrees.
For most people, walking up a 25-degree slope is like a strenuous exercise.
Earlier this month, the state assembly was told that Penang saw 20 road collapses and 68 landslides this year, more than double compared with last year. All the landslides were on the island, with most occurring in the northeast and southwest districts.
Heavy rain has also pushed the Air Itam dam to 99.4% capacity, its highest level since 2021, after more than 500mm of rainfall in its catchment area in just two months.
State officials said the continuous rain has softened soil and aggravated leaks in ageing underground pipes, leading to road cave-ins.
To improve detection of such occurrences, Penang Island City Council has bought a ground penetrating radar system, while the public works department has received RM8.79 million to repair and reinforce 16 high-risk slopes.
Public trust just as crucial
Cheung said rather than emulate Hong Kong’s strategy right away, Penang should start small and build from there.
He also said clear communication is crucial to build public confidence in the system.
“Hong Kong backs its engineering work with public education campaigns, guides for homeowners and regular updates during heavy rain,” he said.
He also stressed the importance of assigning an “owner” or caretaker for every made-made slope, be it a government body, a private business or a homeowner.
“In Hong Kong, we know who is responsible for every slope. That makes follow-up action easier,” he said, adding that such information should be publicised to prevent confusion when problems arise.
This is especially relevant in Penang, where many slopes are close to housing estates or border public infrastructure, making it unclear as to who should inspect or repair them.
Cheung said early warning systems only work if people trust in and act on them, built over years of transparency and community education.
“We do not need to have a perfect system to start protecting people. A simple rainfall-threshold based warning system and clear assignment of responsibilities, together with transparent communication to the public, can already make a big difference,” he added.
