kevin sinclair's hong kong

PUBLISHED : Wednesday, 02 July, 2003, 12:00am
UPDATED : Wednesday, 02 July, 2003, 12:00am

Drive between Ma On Shan and Sai Kung, or over Hong Kong island from Shau Kei Wan to Stanley. Observe roadside slopes, covered with unsightly layers of concrete. These blots on the landscape are muchhated by environmentalists who decry such retaining works as ghastly optical attacks on nature.

Think again.

I'm not saying shotcrete slopes are beautiful - even road-building engineers would not claim that - but I argue they are vastly preferable to the alternative. Without the ugly protective cover, hills would come hurtling down in a chaos of collapsing granite and mud.

To speak in favour of shotcreting is to brand yourself an insensitive slob. It's ecological heresy. So be it.

Consider this. In the first half of last month, Hong Kong officially had 438.7mm of rain. Falling on a slope, the mass of water accelerates as it pours downhill. Carrying heavy loads of earth and debris, it develops power equal to a bulldozer. It rips into unprotected decomposed granite, the bulk of Hong Kong hillsides, and tears it apart. Rain falls unevenly. With clouds buffeting us from the east, Sai Kung and Stanley got 550mm in the first four days of last month. Both areas have long stretches of winding roads with steep-cut flanks. In past years, such rains have meant landslides, deaths and disruption, with major roads closed for weeks. Last month, largely thanks to shotcrete, the rains came down and the slopes stayed up.

In the half century after 1947, at least 470 people died in landslides, most killed when man-made slopes collapsed. The number of landslides has dropped significantly since government contractors started hosing on shotcrete. There are still about 300 incidents reported annually, 27 in the first two weeks of last month. Most are minor washouts. You don't get 71 people killed when a man-made slope turns into slushy mud and buries people alive, as happened at Sau Mau Ping in 1972. We don't see major roads blocked for three weeks as happened in 1997.

In the past 25 years, the government has spent about $6.9 billion on studying and treating slopes - money well spent.

The Geotechnical Engineering Office (GEO) liaises with seven hands-on departments including highways, drainage and water supplies to keep slopes in good condition. It's a big job. When the GEO was set up in 1977 its first task was to find out how many hillsides had been cut into for building sites, roads and other works. They have 54,000 sites catalogued.

The focus now is to make slope improvements look more natural and attractive. Planting gentle slopes with layers of thick grass and bushes is one tactic. Using blocks of stone instead of spraying concrete is another. Colouring shotcrete and disguising it with trees is also being attempted.

Greens are usually swift to roar in outrage - quite rightly - at the vaguest threat to a flowering Bauhinia blakeana and are quick with a quote on issues of rural protection.

But when I asked them to balance their distaste for shotcrete with its unchallenged role in preventing landslides, all major green groups were seized by untypical silence. What's the alternative, I asked?

There was no answer from World Wide Fund for Nature, Friends of the Earth, the Conservancy Association and other groups. They seem unable to come to grips with an unpleasant reality. Shotcrete is ugly, but it works.

Give me a concrete slope rather than a bank of trees that are going to collapse in the next downpour, maybe killing people and taking a road away.