Early warnings for landslides possible with new Hong Kong index, says Geotechnical Engineering Office chief
- The post-rain collapses have killed hundreds in the city, much of which is made up of slopes
- Now the custodians of its hillsides want to notify people of the dangers, and of ways to stay safe
Hong Kong could develop its first early-warning system for landslides, using a new index which gives the risk of the potentially deadly collapses following rainstorms, a top government engineer has said.
The Landslide Potential Index, one of the only such metrics in the world, estimates the risk of landslides in the city based on the intensity and location of rain and the distribution of slopes, the Geotechnical Engineering Office (GEO), which is responsible for the upkeep of hillsides, said.
Hong Kong, where more than 70 per cent of land is made up of slopes, has a history of tragic landslides, with more than 470 fatalities in the 50 years from the end of World War II. In 2018 more than 250 landslides were reported, the highest number in a decade.
“We already have the technology in place to have an early-warning system for landslides, but we also need to make sure people understand the risks and what to do to be safe,” GEO head Pun Wai-keong said.
There is only so much we can do to prevent landslides with engineering. That is why we are trying to educate residents, and the index can decrease fatalities by up to 80 per cent
Ratings on the updated index, introduced in October, are posted online within five minutes of the end of a rainstorm and updated every five minutes. The index gives the risk of landslides from 0 to more than 100, with 10 to 50 being high-risk, 50 to 100 very high-risk, and more than 100 extremely high-risk. After each rainstorm, the risk decreases over time.
The previous index took up to two weeks to calculate and did not have a numbered scale, which was neither user-friendly nor easy to understand, Pun said.