ENVIRONMENT

Extreme weather set to raise risk of landslides

Well over 2,000 natural slopes need reinforcement with heavy rain to come

PUBLISHED : Friday, 11 April, 2014, 4:40am
UPDATED : Friday, 11 April, 2014, 4:40am

Hong Kong should be prepared for the increased risk of landslides as extreme weather conditions are expected to hit the city more frequently and vigorously, the Civil Engineering and Development Department says ahead of the coming rainy season.

The downpour last month which saw the Observatory issue the first black rainstorm alert of the year was an example of extreme weather conditions, said Au Yeung Yan-sang, deputy head of the department's geotechnical engineering office. The office received 11 reports of landslides on that night. In one case, a homeowner in Sai Kung was told to stay out of a section of their flat because of a risk of falling debris.

Au Yeung said the department had started to reinforce slopes, which would keep the risk of landslides low. It strengthens 150 government man-made and 30 natural slopes every year, so they can withstand heavy rain. The department will also work on delivering faster and more accurate landslide alerts, and improve co-operation with other departments, he said.

"It will become more challenging to keep the risk of landslides low in the future," he said. "No government or place can say we can prevent disaster, but we can work on minimising the damage."

Some 2,700 natural slopes had been identified as needing reinforcement, and Au Yeung was satisfied with the rate of strengthening 30 such slopes each year, as most are not in urgent need of work.

Last year, the department received 241 reports of landslides, lower than the average of 300 for the last 20 years. None of the landslide cases last year were fatal. Most of them affected roads, car parks, playgrounds, gardens and other open areas.

One of this year's projects is the slope above Bowen Road, where landslides occurred in 2005 and 2008. No one was injured in either event, but a security-guard booth in Ewan Court was crushed in 2008.

Five concrete barriers are being built to contain as much as 2,000 cubic metres of debris in case of a landslide. In one section, a 30-metre deflection wall will funnel the debris into one of the structures.

Soil nails will be installed at distressed areas to help stability, while mesh fencing will stop debris reaching nearby buildings.

The HK$227 million project is expected to be completed by the end of the year, Au Yeung said.