Flood Prevention Infrastructure

The Drainage Services Department is working on a series of major flood control projects in the northwestern and northern parts of the New Territories and in West Kowloon, costing about $12.3 billion.

In the northwestern New Territories, improvement works to 26.5 kilometres of the major river network have been completed, covering Shan Pui River, Kam Tin River and Ngau Tam Mei main drainage channel. As a result, the flood risk in the surrounding areas has been reduced.

Construction of Yuen Long Bypass Floodway and San Tin eastern main drainage channel is in progress. When the work is finished in 2006, the flooding problem in areas of Yuen Long New Town and east of San Tin will be resolved. Planning and design work for San Tin western drainage channel is under way.

In the northern New Territories, the critical flood mitigation undertakings include Shenzhen River Regulation Project Stage III, which involves training four kilometres of river channel from Lo Wu to its confluence with Ping Yuen River, is due for completion by the end of 2006.

Improvement work on 1.7 kilometres of Ping Yuen River to tackle the flooding problem in Ta Kwu Ling will be finished by early 2006, while work on 1.8 kilometres of Ma Wat River in Kau Lung Hang, Tai Po North, is due for completion by the end of 2008. Design work for another 19.5 kilometres of drainage channels in the northern New Territories, including upstream portions of Ping Yuen, Sheung Yue and Ng Tung Rivers, is also in hand. Upon completion of these remaining river training works, the regional flooding problem in the northern New Territories will be overcome.

There are 25 village flood pumping schemes in operation to protect low-lying villages from flooding. These schemes involve constructing a bund around a low-lying village and pumping storm water from the area within the bund to an outside channel during rainstorms. Similar schemes for Shui Pin Tsuen and Tai Kiu are under construction.

In West Kowloon, the construction of the large flood storage tank underneath Tai Hang Tung Recreation Ground and the stormwater transfer tunnel from Kowloon Tong to Kai Tak Nullah, were completed. The Stage III works, which include the laying of about 12 kilometres of stormwater drains in Yau Ma Tei, Sham Shui Po, Kowloon Tong and Yau Yat Tsuen, are due to be finished in 2007. On completion, the flood risks in West Kowloon will be substantially reduced. Implementation of the Lai Chi Kok Transfer Scheme is being planned to further raise the flood protection level in Lai Chi Kok, Cheung Sha Wan and Sham Shui Po to the required standard.

Serious flooding was recorded in Hong Kong North in past rainy seasons. The department is planning to build the Hong Kong West Drainage Tunnel, which consists of a 6.25 metre diameter section of 4.5 kilometres from Tai Hang to Aberdeen, and a 7.25 metre diameter section of 6 kilometres from Aberdeen to Pok Fu Lam. It includes a total of 36 flow intakes for intercepting flows from the upper catchments for discharge into the sea at Pok Fu Lam. This tunnel will help reduce the flood risks at the lower catchments — and hence the hazard of overland flows down steep roads in Mid-Levels — and the scale of the online drainage improvement works in the lower catchments. Preliminary design and investigation consultancy work is close to completion, while detailed design and construction will be awarded soon.

The department has completed eight Drainage Master Plan Studies since 1994 to review the condition and performance of the existing stormwater drainage systems in various flood-prone areas throughout Hong Kong. In view of current and future development needs, further packages of improvement works with greater focus on the secondary drainage networks have been included in the Public Works Programme and are at different stages of planning, design and construction.

Under a preventive maintenance programme, the public drainage system is regularly inspected and desilted before and during the rainy seasons to ensure that stormwater is discharged.

In 2005, the department maintained 2 537 kilometres of watercourses, river channels and drains, from which 40 077 cubic metres of silt were removed.

The importance of flood prevention is promoted through various public education activities. Promotional pamphlets and advisory notes are distributed to villagers and property management offices before the rainy season. In addition, the department has received students at the San Tin Flood Prevention Information Centre and organised site visits for district councillors and the media to promote their understanding of the department's work and thereby enhance public awareness of flood prevention.