The Government has been continuously improving the Hong Kong Slope Safety System and formulated strategies to prepare for the threat of extreme rainfall brought about by climate change, which covers three aspects viz prevention, preparedness and education. Key measures include:
Strengthening slopes against extreme rainfall to prevent landslides
The GEO implements the Landslip Prevention and Mitigation Programme (LPMitP) to manage the landslide risk of both natural hillside and man-made slopes in a holistic manner. Under the LPMitP, the Government's pledged annual outputs are:
- to upgrade 150 man-made slopes;
- to conduct safety-screening studies on 100 private man-made slopes; and
- to construct mitigation measures for 30 vulnerable natural hillside catchments each year.
The GEO also endeavors to enhance the prevailing slope engineering design standard and preventive measures to strengthen the slopes against extreme rainfall events, in order to reduce the probability of occurrence of severe landslides. These measures include:
- enhancement of slope drainage design standard and improvement of slope surface drainage system to cater for the possible increase in precipitation due to extreme rainfall events;
- use of soil nails to enhance the robustness of slope;
- construction of flexible and rigid barriers to contain debris flow and thus minimising the impact to adjacent facilities;
- use of unmanned aerial hydroseeding technique to revegetate landslide scars on natural hillside as well as identification of landslides on aerial photographs using artificial intelligence in order to enhance the effectiveness of evaluating landslide risk; and
- use of innovative technology to regulate the regional groundwater.
Enhancing emergency preparedness and response to cope with severe landslide events
From technical viewpoint, the forecast of climate change effects bears many uncertainties. It is not practical to rely solely on engineering solutions in managing the landslide risk brought about by extreme rainfall events. Enhancing the Government emergency preparedness and response is equally important.
The GEO provides a 24-hour year-round landslide emergency service. Geotechnical engineers will be deployed to inspect the site and advise various departments on appropriate mitigation measures or emergency works to be taken in case of danger arising from landslides, thereby ascertaining public safety. Besides, the Government regularly conducts training events and operational drills to ensure adequacy and effectiveness of the emergency response system. The GEO has also introduced virtual reality trainings to empower the geotechnical engineers in dealing with severe landslide incidents.
The Government proactively make use of new technology to enhance emergency preparedness and response. The GEO has developed and put on trial a novel landslide detection system "Smart Barrier", applying modern information technology for monitoring the condition of landslide debris-resisting barriers. Many barriers are located at natural stream course or hillside, where accumulation of landslide debris behind the barriers may easily go unnoticed. The "Smart Barrier" allows all-weathered and non-stop monitoring of the barriers' conditions and provides alerts via mobile application in the event of any accumulation of landslide debris, thus forewarning the occurrence of major debris flow. This enables relevant government departments to arrange timely emergency evacuation of nearby residents and minimise any possible casualties.
Improving the community resilience against landslide risk
Another important initiative is to raise community resilience against natural disasters such as extreme rainfall and severe landslide events. The Government has been promoting personal precautionary measures under emergency situations. When natural disaster occurs and before the arrival of rescuers, the public may follow pragmatic self-help tips to protect themselves, minimise damages and avoid casualty.
The GEO and the Hong Kong Observatory jointly operate the "Landslip Warning System". By using a statistical model between rainfall intensity and landslide frequency, the number of landslides induced by a rainstorm can be estimated based on real-time rainfall data and rainfall forecasts. Landslip Warning will be issued when necessary to alert the public to take appropriate precautionary measures.
The GEO instils simple yet crucial safety messages into the community through public education, publicity events and public information services, which include:
- the public should always remain vigilant about warning and advice issued by the Government during adverse weather;
- when Landslip Warning is in force, or during heavy rainfall, the public should stay away from slopes, watch out and report for signs of landslide danger; and
- the public must strictly follow the instructions of the rescue personnel and act promptly.
For private slopes, the GEO continues to implement community education programme to promote the importance of slope maintenance in preventing landslides. We have set up a Community Advisory Unit to proactively provide community advisory services to owners and help them fulfil their slope maintenance responsibilities.