Due to extreme weather in recent years, the frequent and severe rainstorms in Hong Kong have made flood prevention very challenging to the Drainage Services Department (DSD). To nip it in the bud, the Government is seeking funding approval of about $8.4 billion to carry out drainage improvement works in various districts to enhance the capacity of flood prevention. This time, I have invited a colleague of the DSD to tell us how they improve Hong Kong’s drainage systems to mitigate the impact of rainstorms and flooding.
Over the years, the DSD has been working very hard to prevent and mitigate flooding by adopting a three-pronged flood prevention strategy: stormwater interception in the upstream, flood storage in the midstream and drainage improvement in the downstream. The strategy has been effective in mitigating the flood risk brought by rainstorms. As the DSD has eliminated 127 flooding blackspots since 1995, there are currently only four flooding blackspots in Hong Kong. To further enhance flood prevention capacity, the DSD will continue to carry out drainage improvement works in various districts, and the Sau Nga Road Stormwater Storage Scheme in Kwun Tong is one of the projects.
Underground stormwater storage tank at Sau Nga Road Playground
According to Engineer (Drainage Projects Division) of the DSD, Ms KWONG Siu-ting, Kate, on top of the fact that Kwun Tong town centre is located in low-lying areas, the existing drainage channels in the areas along Tsui Ping Road and Kai Lim Road are unable to cope with the drainage, making these areas prone to flooding during rainstorms. In fact, there were serious flooding incidents in the past. With an increasing level of rainfall and rising sea levels as a result of climate change, more frequent and serious flooding can be expected. Therefore, the department has proposed to construct an underground stormwater storage tank at Sau Nga Road Playground with a capacity of about 64 000 cubic metres (which is equivalent to the total volume of about 25 standard swimming pools) to help reduce the burden of the local drainage system.
Reprovisioning of a playground above the stormwater storage tank
According to Ms Kate KWONG, as a preventive measure, the stormwater storage scheme not only can effectively reduce flood risk in the low-lying areas in the town centre, but can also avoid extensive drainage improvement works on busy roads and streets in Kwun Tong. We can also seize the opportunity to fully utilise precious land resources to achieve “single site, double use” by constructing a flood prevention facility for Kwun Tong residents and reprovisioning a playground above the stormwater storage tank to improve the existing recreational facilities at the playground, including the provision of more green space and fitness facilities. If funding is approved this year, the project will commence in the third quarter of this year at the earliest for completion in 2028.
Reducing surface runoff to the downstream
Ms Kate KWONG tells us that Sau Nga Road Playground is situated at the mid-stream catchment. There is also enough space to construct a stormwater storage tank and other supporting facilities underneath the playground. Constructing an underground stormwater storage tank there can intercept stormwater flow from the upstream and midstream for storage during rainstorms, reducing surface runoff to the downstream. Moreover, cost-effectiveness has been taken into account during site selection, only minimal alterations have to be conducted to the existing drainage network and structure.
Collecting real-time data for operational control of stormwater storage tank
The department will inject innovative elements into the Sau Nga Road Stormwater Storage Scheme. For example, the underground stormwater storage tank will be equipped with a smart system to monitor and control the operation of the storage tank by collecting real-time data.
Apart from being connected to the weather forecast control system of the Hong Kong Observatory, the stormwater storage tank will have its volume of discharge controlled by water level sensors installed in the upstream and downstream to make good use of the discharge capacity in the downstream, resulting in effective stormwater storage. Besides, the smart system of the stormwater storage scheme can regulate the storage of rainwater and discharge it into the revitalised Tsui Ping River moderately to maintain a certain flow rate in the water body.
As regards the proximity of the construction site to the United Christian Hospital, the department will permanently relocate the existing vehicular entrance/exit of the playground at Sau Nga Road to Hiu Kwong Street, in order to reduce the impact on the hospital.
Bringing multiple benefits
To cope with climate change, the DSD will continue to enhance Hong Kong’s flood prevention capacity. Apart from Sau Nga Road, the department has also planned to carry out stormwater storage schemes at other locations. In future, I will continue to share the details of other schemes so that the public can better understand how the department adopts a multi-benefit approach in drainage construction to alleviate drainage problems, optimise land use, improve the living environment of the public, and promote sustainable development.
Six CIFs with 20 000 beds to be operational within the month
In addition, to meet the need for isolating COVID-19 confirmed patients, I said at a press conference earlier that six CIFs constructed by China State Construction International Holdings Limited (China State Construction) will come into operation this month, providing a total of about 20 000 isolation beds. Among them, the four facilities in Tsing Yi, San Tin, on the Hong Kong Boundary Crossing Facilities Island of the Hong Kong-Zhuhai-Macao Bridge, and at Ma Sik Road, Fanling, commenced operation on 1, 9, 12 March and today (13 March). At present, the occupancy rate of the two projects in Tsing Yi and San Tin is about 80 per cent on average. The remaining projects in Hung Shui Kiu and Tam Mei, Yuen Long will also be delivered to the HKSAR Government for operation within this month.
About 20 000 additional beds to be provided in May
China State Construction is also responsible for the construction of two larger community isolation and treatment facilities in Penny’s Bay and the former runway area of Kai Tak, some of the beds are expected to be ready in phases starting from May. The two projects will eventually provide a total of about 20 000 additional beds.
Moreover, site formation for the project providing about 10 000 beds in the Loop, which is under construction by the China Construction Science and Industry Corporation, is in full swing. China Construction Science and Industry Corporation is also building an “emergency hospital” with about 1 000 beds in the Loop, the construction of which has already commenced and the hospital is expected to provide the first 500 beds in April.
I would like to thank the Central Government once again for its full support for these projects, which are of great significance to Hong Kong, and for the co-ordination and promotion of these projects by the Liaison Office of the Central People’s Government. I would also like to thank China State Construction for their full commitment over the past period, especially the large number of frontline workers in Hong Kong and the Mainland who have been working round the clock on these projects. The HKSAR Government will do its utmost to support and cater for all the needs of these projects in terms of engineering and related matters. We believe that as long as we can work together and be united, Hong Kong will be able to win this battle against the epidemic.
13 March, 2022Back