LCQ16 : Flooding problem at five flood prone areas actively tackled

Following is a question by the Hon Ambrose Lau and a written reply by the Secretary for the Environment, Transport and Works, Dr Sarah Liao, at the Legislative Council meeting today (May 21) :

Question:

Regarding the progress of flood prevention works at five most serious flood areas in the territory (namely Kan Tau Tsuen and Chow Tin Tsuen in Ta Kwu Ling; Yau Tam Mei Tsuen, Yau Tam Mei San Tsuen and Chuk Yuen Tsuen in Yuen Long; KCRC Bridges in Kau Lung Hang, Tai Po; Lam Tsuen Valley Basin in Tai Po; and Nathan Road between Boundary Street and Prince Edward Road West), will the Government inform this Council:

(a) why the flood prevention works at none of the above areas have been completed so far even though the flooding problems there have been categorized as the most serious; and

(b) the measures to mitigate the flooding problems in these areas before the completion of the relevant flood prevention works?

Reply:

Madam President,

(a) The Government has placed great emphasis on flood prevention and has committed significant resources to tackle the flooding problem in the New Territories. The Government has already completed about $4 Bn of works in the downstream sections of major rivers and channels, providing initial relief to flooding. As a result, the previous flood prone areas such as those in the vicinity of Tin Shui Wai, Shan Pui River in Yuen Long, Tin Ping Shan and Lo Wu have been relieved of flood risks. We are now actively carrying out river training works in the midstream and upstream sections of the major rivers in the New Territories including Kam Tin River in Yuen Long, and River Ganges. Major flood prevention projects under construction include Yuen Long bypass floodway, the San Tin eastern channel, and the Regulation of Shenzhen River Stage III.

The five flooding blackspots mentioned have their own inherent geographic constraints that the flooding problem cannot easily be resolved without large scale drainage improvement works, which often need to be completed in stages from downstream to upstream. The works completed so far and those under planning/construction are listed below :

(i) Ta Kwu Ling area including Kan Tau Wai and Chow Tin Tsuen

The Ta Kwu Ling area is a low-lying area within the Ganges River basin which discharges into Shenzhen River. Hence, it is subject to the tidal effects inherited from the Shenzhen River during the flooding period. The extensive flooding of the Ta Kwu Ling area will be eliminated after the full completion of Shenzhen River Regulation Project and the rehabilitation of River Ganges in 2006. The Shenzhen River Regulation Project Stage I and Stage II at the downstream were completed in 1997 and 2000 respectively while Stage III commenced construction in Dec 2001 for completion by early 2006. The rehabilitation of River Ganges commenced construction on 13 May 2003 for completion by end 2005.

(ii) Yuen Long Ngau Tam Mei area including Yau Tam Mei Tsuen, Yau Mei San Tsuen and Chuk Yuen Tsuen

Ngau Tam Mei is in the low-lying area. The training works of the downstream Kam Tin River, which has helped relieve the flood risk of Ngau Tam Mei, was completed in 1999. River training works upstream of San Tin Highway under "29CD - Main Drainage Channels for Ngau Tam Mei Phase 2" have recently been completed in April 2003. While we expect the full completion of the main drainage channel between San Tin Highway and Kam Tin River under "100CD - Main Drainage Channels for Ngau Tam Mei Phase I" later this year, the drainage channel has already been formed to line and level and starts discharging water. Furthermore, the village flood pumping scheme at Chuk Yuen Tsuen has already been completed in March 2003. It is envisaged that the flooding problem at Ngau Tam Mei will be significantly relieved towards end 2003.

(iii) Tai Po Kau Lung Hang KCR underpass

The streamcourse underneath the KCR bridge and the natural water course at the upstream Yuen Leng area do not possess adequate drainage capacity to meet the flood flow. The training works of the downstream Ng Tung River have recently been substantially completed. It is expected that the flooding problem at Kau Lung Hang could be resolved by the training of Ma Wat River under the drainage project "112CD - Drainage Improvement in Northern New Territories Package A". The project is currently at detailed design stage for construction to commence in 2004 with a target completion date by end 2007.

(iv) Tai Po Lam Tsuen Valley

The existing Lam Tsuen River and She Shan River do not have adequate capacity to meet flood flow under extreme events. Under the "109CD - Drainage Improvement in Sha Tin and Tai Po Package C", the two rivers will be trained to improve the drainage capacity. The project is currently under detailed design stage with a target completion date by 2009. We are actively considering the feasibility to advance the programme of the project.

(v) Nathan Road between Boundary Street and Prince Edward Road West

In urban areas like West Kowloon, the existing drainage systems were built long time ago and are not up to current flood protection standards. To provide an initial relief to the flooding in Mong Kok, the drainage improvement works at Nathan Road between Boundary Street and Nullah Road have already been completed. Works under different stages of West Kowloon Drainage Improvement Scheme have been progressing well for completion in phases from year 2003 to 2007. Construction of a flood water storage tank at junction of Boundary Street and Tai Hang Tung Road and the Kai Tak Transfer Scheme are in hand and are scheduled for completion by 2004. It is expected that the flooding problem in this area will be significantly relieved by end 2004.

With the progressive completion of the above flood prevention projects, it is expected that the extent and severity, as well as the recurrence of widespread flooding at these locations will be significantly reduced.

(b) There are interim improvement and maintenance measures in place to help alleviate the flooding problem before the completion of the long-term improvement measures. Local drainage improvements have also been implemented to provide initial relief wherever possible.

Before the completion of the flood control projects, regular and preventive maintenance are carried out to ensure that the existing drainage will be discharging flood water in their full capacity free from blockage or siltation. DSD will regularly inspect, desilt and repair the stormwater drainage system before and during the rainy season to ensure that any blockages and defects will be cleared and rectified immediately.

At locations where flooding may cause high risks to the local residents, flood warning systems (flood sirens) have been installed to monitor the flooding situations and alert residents/villagers before the arrival of floodwater.

There is also a list of flooding blackspots compiled to facilitate the deployment of resources to carry out immediate relief measures during adverse weather conditions. DSD will closely liaise with other relevant Government departments and personnel in charge of construction sites to avoid flooding due to blockage of roadside gullies, drains or watercourses by rubbish or construction debris.

During emergency, DSD will activate their Emergency and Storm Damage Organization (ESDO) and Emergency Control Centres (ECCs). To achieve higher responsiveness in the 2003 rainy season, DSD would deploy dedicated emergency night gangs for the whole Hong Kong, working from 10:00 p.m. till 8:00 a.m. everyday. The gangs would be equipped with water jetting units for clearing emergency drainage blockage and would be supervised by DSD staff.

End/Wednesday, May 21, 2003

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