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Following is a speech by the Director of Drainage Services, Mr John Collier, at the department's Flood Prevention Roving Exhibition Opening Ceremony today (Friday) :

Honourable Guests, Ladies and Gentlemen, welcome to the Opening Ceremony of the Flood Prevention Roving Exhibition of the Drainage Services Department. It is our honour to have you here with us today.

It is the first day of our roving exhibition which will be held in three different locations in the coming three weekends. We have chosen West Kowloon, Yuen Long and Sheung Shui for the exhibition to ensure that the communities most affected by flooding will have a better chance to see what the Government is doing in combating flooding.

Flooding in Mong Kok

Hong Kong has experienced very fast growth in the last twenty/thirty years. West Kowloon, which encompasses highly urbanized areas of Tsim Sha Tsui, Yau Ma Tei, Mong Kok, Kowloon Tong, Sham Shui Po and Lai Chi Kok, is a major residential and commercial area with over 700,000 people. The community services and infrastructures within West Kowloon are under tremendous pressure in coping with the pace of its growth. This is also true in respect of the drainage and sewerage systems. And even though we started upgrading works in West Kowloon in 1992, we still have a long way to go.

1997 was a remarkable year for Hong Kong; on the political side, we celebrated our reunification with Mainland China. Weather wise, we experienced the heaviest annual rainfall ever - 3,433mm. To the people in Mong Kok, it was a year of severe flooding. In 1997, the Mong Kok catchment which extends to Beacon Hill received a total of 12 hours of rainfall that exceeded 40mm in one hour. This is against an average of around 3 hours per year since 1984.

Solutions to Flooding Problem

To solve the flooding problem, drainage systems for the whole of West Kowloon will need to be improved in the longer term. Initial studies showed that around 100km of on line drainage improvements would be required in order to eliminate flooding. This would require a 10-year 3-stage improvement programme and cost over $3.5 billion.

In April 1998, we have started two contracts of the Stage I improvement works. We shall commence the last contract of the Stage I works that include the area worst affected at Nathan Road, Mong Kok, in October. All of these works will be completed in 2002.

The proposals for remaining stages have now been reviewed and we are considering other options which would require less disruption to the community. For the Mong Kok catchment, options are to divert flows to the lower end of the Kai Tak Nullah by the construction of a 1,500m long transfer tunnel and to construct a pumped storage scheme at Tai Hang Tung to attenuate peak flows in the open nullah. Our target remains to start the next stage of the improvement project in end 1999 for completion in 2004. By that time, the threat of flooding in Mong Kok and West Kowloon will be very much lowered.

Measures Already Taken

During the winter of 1997/98, we carried out large-scale desilting work in the new culverts which extend the drainage system through the new western reclamation. This work, together with other short term measures, has lessened the impact of flooding events at Nathan Road, Mong Kok in that floodwater receded much quicker than in 1997.

Currently, we are installing roadside U-channels at the junction of Nathan Road and Boundary Street and 2 large relief drains (1.35m and 1.25m dia.) along Playing Field Road and Tung Choi Street. The U-channels are expected to complete in October and the relief drains before the 1999 wet season in order to bring additional relief to the flooding situation in the area.

For the rest of this rainy season, our maintenance staff will continue on monitoring the situation in Mong Kok. When adverse weather comes, we will dispatch our staff to major flooding black spots to carry out immediate relief measures. We shall maintain close coordination with relevant Government departments in this respect. We aim at eliminating major flooding black spots in the West Kowloon area in the next few years.

Road Opening in Urban Areas

Major road openings for drainage and sewerage improvement projects in urban areas cause traffic congestion and inconvenience to the community. The Drainage Services Department is making every effort to minimize these nuisances. One of the traditional methods is to carry out construction works with other Government departments in order to minimize road opening. Apart from these, we consider a number of different methods to minimize road opening in busy urban roads:

(1)by no-dig excavation methods such as pipe-jacking or mini tunneling techniques. These techniques involve minimum road openings which are usually carried out for the construction of access shafts. Other excavation works are basically performed underground.

(2)by adopting a new contract management method in drainage improvement projects in which excavation of roads will be controlled by way of works orders issued to the contractor. These works orders will only be issued to the contractor if the engineer is satisfied with the progress of the works, the actual traffic conditions and the contractor's available resources.

(3)by considering different innovative options that would cause less disruption to the community. These options include the diversion of stormwater to other catchments by large intercepting tunnels built at the upper catchment, and the storage of floodwater in order to attenuate peak flows in main drains.

(4)by improving the coordination with other Government departments, such as the Transport Department and Traffic Police, in terms of the requirement for carrying out a detailed Traffic Impact Assessment in the design stage, and the design of the temporary traffic arrangement during construction.

Flooding in Other Areas

Flooding also occurs in the northern New Territories where there are low-lying areas and natural flood-plains. To tackle this problem, we have formulated a flood prevention strategy for the Northern New Territories that is based on the river training schemes and village flood protection schemes for low lying flood-prone villages. In the Northwestern New Territories, we have achieved some success in minimizing flooding as we are progressing well with the construction of major drainage channels and the 15 village flood protection schemes are working well.

In the Northern New Territories, the most critical flood mitigation is the 3-stage Shenzhen River Regulation Project which started in 1995. Upstream of the Shenzhen River on Hong Kong side, the training of Indus River and Beas River will commence in phases by the end of 1998. We expect that drainage conditions in these areas will gradually improve when these works are making progress in the Northern New Territories. In total we are spending in excess of $6 billion on these measures.

Conclusion

The Drainage Services Department is determined to provide quality services both in sewage treatment and disposal, and in flood prevention. Professionalism, accountability and openness are the core values we rely on in delivering our services. Finally, I thank you all for coming to this opening ceremony. I hope you enjoy your time in this exhibition. Good luck and good health.

End/Friday, September 11, 1998

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