(By Anson Lin)
As part of the Eco Expo Asia 2024, the Belt and Road delegation paid a visit to the Po Shan Drainage Tunnel - Landslide Sci-Tech Chamber yesterday (Oct. 31).
Organized by the Geotechnical Engineering Office (GEO), one of seven constituent offices of the Civil Engineering and Development Department (CEDD), the visit aims to introduce the history of landslides in Hong Kong as well as the innovative technology adopted in the Po Shan Drainage Tunnel project, enhancing interaction and mutual-learning on the topic of slope safety and environmental protection.
There are four galleries in the Chamber, including the Po Shan Memorial Gallery, the Climate Change Impression Gallery, the Landslide Wisdom Gallery and the Drainage Tunnel Expression Gallery, which introduce relevant background information and details of the project design in a logical order.
In 1972, a catastrophic landslide on Po Shan Road in the Mid-Levels destroyed numerous homes and claimed 67 lives.
Subsequent investigations revealed that the Po Shan hillside was affected by high groundwater levels, making it particularly susceptible to landslides.
To prevent such catastrophe, the GEO installed horizontal drains in the Po Shan area to lower the groundwater table in the 1980s, improving the stability of the hillside against large-scale slope failure.
However, monitoring data in the early 2000s revealed that some of the horizontal drains exhibited a decreasing trend of water outflow and the groundwater levels could be rather high locally during periods of heavy rainfall.
Subsequently, the GEO designed an innovative and sustainable groundwater regulation system to control the groundwater level in the Po Shan hillside, entitled the "Po Shan Drainage Tunnel".
Completed in December 2009 at a cost of approximately HK$165 million, the system comprises a pair of drainage tunnels (3.5m diameter and a total length of 500m) and a network of 172 sub-vertical drains.
It is equipped with an automatic real-time groundwater monitoring system to facilitate the GEO to control the groundwater levels.
During the visit, the representatives proactively interacted with the engineers and shared their insights into the project.
From my perspective, a site visit to the Landslide Sci-Tech Chamber is not only enlightening for professionals but also holds significant educational value for individuals.
The presentation of the 1972 catastrophe in the Po Shan Memorial Gallery serves as a reminder of nature's might.
Though it may have been far away from us, the memory of the record-breaking rainfall on September 7 & 8, 2023 remains clear for most of us. With climate change, we human beings are faced with great challenges.
They are long-term challenges, which cannot be resolved by just one attempt. Instead, they entail sustained commitment and action.
While the GEO installed horizontal drains in the Po Shan area in the 1980s, monitoring data indicated that problems still existed.
In response to new challenges, an innovative and sustainable groundwater regulation system was developed, exemplifying the long-term dedication of the engineers involved.
Next time it rains heavily, I will certainly think of the tunnel, which quietly safeguards our safety, and of the engineers who have devoted themselves to this vital project.
I am pleased to know that the tunnel is available for public visits with applications, which helps to arouse the public's awareness of slope safety and environmental protection.
From my hands-on experience to get to the Chamber, I would like to suggest the entrance of Po Shan Drainage Tunnel - Landslide Sci-Tech Chamber be marked on Google Map so that the public can find it more easily.
Moreover, it's better to set some road signs nearby because it takes about 20 minutes if we start our journey from Sai Ying Pun Station, during which we need to climb long stairs to arrive at the destination.
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