Extreme weather is becoming more frequent, as the Geoengineering Department announced yesterday that they received 601 reports of landslides last year. In addition, this month, the Geoengineering Department and the Hong Kong Observatory have collaborated to launch a new “Landslide Special Warning” to remind the public of the landslide risks in certain local areas.
According to the Geoengineering Department, they received a total of 601 reports of landslides last year, which is significantly higher than the 76 reports in 2022 and also exceeds the average of about 300 reports per year over the past 35 years. However, the figure of 601 is still lower than in years with higher rainfall, such as 863 reports in 2008, which did not result in any casualties.
The record-breaking rainfall brought by a severe storm on September 7th last year caused severe landslides on Shek O Road and Yiu Hing Road. In total, the department received 181 confirmed reports of landslides, with seventy percent of incidents affecting roads, pedestrian walkways, shanties, and buildings, necessitating road closures and evacuation of some residents for emergency repairs.
Preliminary investigations have shown that the main causes of multiple landslides were overflow from streams, water channels, or drainage ditches, especially those blocked by mud, rocks, and dry leaves, triggering landslides. The department stated the need to study how to manage overflows to reduce landslide risks. Additionally, some larger incidents may be related to illegal slope works or unauthorized constructions.
The Geoengineering Department further mentioned that although most landslides triggered by severe storms are small in scale, in cases similar to those on Shek O Road, where mud and rocks blocked the only carriageway, they seriously affected residents’ daily lives. The government will focus on inspecting slopes next to the sole carriageway and prioritize reinforcement works. Approximately 500 government-managed artificial slopes have been identified, with plans to complete inspections before the end of the month ahead of the rainy season.
With extreme weather events on the rise, the Geoengineering Department has introduced a new service in collaboration with the Hong Kong Observatory called the “Landslide Special Warning” this month. Even if the landslide risks in most parts of Hong Kong have not reached the level to issue warnings, the “Special Warning” will list high-risk areas to remind citizens to be cautious.
Deputy Director of the Geoengineering Department, Kam Ka-wah, explained that the issuance of the “Special Warning” is based on the accumulated rainfall in the past 24 hours to assess the landslide risks in the affected areas. Based on past data, when the 24-hour rainfall exceeds 300 to 400 millimeters, residents should be on high alert. The warning advice is dynamic and does not have fixed criteria as it also considers factors such as the impact range of heavy rain and the number of slopes. Furthermore, authorities will explore the use of artificial intelligence to enhance landslide risk assessment capabilities.