Precautionary flood prevention works
On the morning of 18 July, Tai Po District recorded an hourly rainfall of 70 to 80 millimetres (i.e. reaching the level of black rainstorm signal) for consecutive two hours, resulting in serious flooding in Ting Kok Village and Tai Mei Tuk Village. After the incidents, a number of departments provided immediate assistance and support to villagers being affected. Few days ago (21 July), I visited the two villages and listened to the requests of villagers and explained to them the relieving works by departments in order to ease their concerns. In the past few days, the Drainage Services Department (DSD), the Buildings Department (BD), the Water Supplies Department and the Tai Po District Office have spared no effort in dealing with the aftermath of the flooding, including urgent repairs to the damaged river sections and removal of boulders and debris washed down from upstream, so as to restore the drainage capacity of the river as soon as possible.
Regarding the village house in Ting Kok Village with the foundation of its platform undermined by flooding, I note that DSD has been working closely with BD to carry out urgent repairing works so as to strengthen the foundation of its platform, and the works are expected to be completed soon. Upon completion, BD will inspect again the structural safety of the house. I have explained the situation to the house owner to allay his worries.
With the onset of rainy season in Hong Kong, we cannot underestimate the devastating effects of rainstorms. I have urged relevant departments to exercise greater vigilance, carry out flood prevention measures properly and maintain close communication with District Council members and residents, so as to put public safety on top priority.
Review completed and proposals made
Apart from solving the problems faced by the villagers at full speed, DSD will soon complete the Review of Drainage Master Plan in Tai Po, which aims to assess and analyse the drainage performance of about 170 kilometres long existing drainage system in Tai Po District, and put forward practical mitigation proposals to cope with the needs of future development and the threat of climate change.
For example, the review finds that the drainage capacity of Shan Liu River, a natural watercourse passing through Ting Kok Village, is insufficient and sections of the river cannot cope with severe rainstorms. As both sides of the Shan Liu River are predominantly private land, widening of the river is not quite feasible. DSD preliminarily proposed intercepting some of the flow at upstream of Shan Liu River to relieve the overloading situation at downstream so as to reduce the flooding risks at Ting Kok Village. DSD is currently looking into two flow interception schemes: one is to build large underground drains along Shan Liu Road; and the other is to build a drainage tunnel which partially diverts the flow from upstream of Shan Liu River and directly discharges to the sea. However, both schemes may involve resumption of private lands and cause inconvenience to the villagers during construction. I wish different stakeholders can provide their views, show their support and tolerance when DSD carries out the works in future. As to Tai Mei Tuk Village, the review proposes to construct flood wall at a section of a village nullah as well as deepening a section of the upstream natural watercourse for enhancing its drainage capacity.
DSD will take forward the planning and design of the mitigation proposals in relation to the two villages as soon as possible, and targets to initiate the project in 2018. DSD will consult the Tai Po District Council (TPDC), village representatives and villagers in due course, with a view to implementing feasible mitigation proposals agreed by all parties concerned at an early date. Meanwhile, DSD will closely monitor the drainage condition in Ting Kok Village and Tai Mei Tuk Village when amber rainstorm signal or above is issued.
Preventive works to mitigate flooding
In fact, the Government has all along been implementing flood prevention works. Over the past two decades, DSD has completed about 90 major flood prevention works.
We have trained more than 100 kilometres of rivers in the New Territories, including Kam Tin River, Shan Pui River, Shenzhen River, Ng Tung River and Sheung Yu River. We have also implemented 27 village flood protection schemes. With the completion of the above works, the flooding situation in the New Territories has remarkably improved.
Flooding blackspots gradually eliminated
The completion of the major flood prevention projects has remarkably reduced the number of flooding blackspots. Over the past two decades or so, DSD has eliminated a total of 124 flooding blackspots with seven still remaining. Drainage improvement works for three of the flooding blackspots have already been completed and commissioned, with their effectiveness being monitored. These blackspots will be eliminated when appropriate. As regards the remaining four blackspots, improvement works are currently at the planning and design stages. DSD will step up routine inspection and conduct regular clearance at these remaining blacksports. DSD will also activate its Emergency Control Centre in times of heavy rainstorm and inclement weather, and in case of flooding at these blackspots, emergency measures including placing of sandbags and clearance of outlets will be carried out to alleviate flooding.
Furthermore, major flood prevention works costing about $12.6 billion are currently under planning, design and construction by DSD to enhance further Hong Kong's flood protection levels. Among them are the Kai Tak River Improvement Works and the Regulation of the Shenzhen River Stage IV, both of which are in progress. Looking ahead, DSD will continue to review the drainage systems in various districts to cope with the needs of future development and the impact of climate change.
Regular inspection, desilting, repair and maintenance
DSD formulates preventive maintenance programme each year, through regular drainage system inspection and timely repair and maintenance works, to ensure the drainage systems function properly.
DSD conducts regular inspections on cross territorial drainage systems, including survey using closed circuit television (CCTV). DSD’s staff inspect manholes, intakes and outlets of drains, nullahs, river channels and watercourses about once every one to three years, and conduct functional and structural checks on underground pipelines about once every five to 10 years to ensure normal operation of drainage systems. In 2016-17, DSD investigated over 2 000 kilometres of drainage systems (including nullahs, river channels and underground pipelines) and about 60 000 manholes, and carried out CCTV surveys for about 300 kilometres of drains. As regards desilting works, DSD regularly cleans the drains, removes or trims any vegetation and clears debris blocking river flow. DSD enhances the above works before rainy season. In 2016-17, DSD cleaned over 700 kilometres of drains and rehabilitated about eight kilometres of pipelines. If any defect or leakage is found in the drainage systems during inspection, DSD will conduct repair and maintenance works, rehabilitation or replacement of pipelines as soon as possible.
Lastly, I would like to express my heartfelt thanks to the Chairman of the TPDC, Mr CHEUNG Hok-ming; Vice Chairman of the TPDC, Ms WONG Pik-kiu; Chairman of the Environment, Housing and Works Committee of the TPDC, Mr CHAN Siu-kuen; TPDC member, Dr LAU Chee-sing; village chiefs; Director of Drainage Services, Mr TONG Ka-hung, Edwin; Assistant Director of Water Supplies (New Territories), Mr CHAN Chung-kun; and District Officer (Tai Po), Ms LUI Siu-chu, Andy, for accompanying me during the site visit a few days ago. Colleagues from various departments and I will “attend to the urgent needs of the public”. Hopefully, through our collaboration, close communication, appropriate follow-up actions and a wide range of improvement works, we can ensure that Hong Kong people lead an enjoyable life without worries.
23 July, 2017