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| | Flood Prevention in the New Territories | | | | Q1 Why is there always flooding in the NT? What is Government's plan to alleviate the problem? top | | | The NNT and NWNT are the two major flood prone areas in the territory. Due to the low-lying topography in these areas, the overflow of natural watercourses, which do not have adequate capacity to cater for the discharge, in times of heavy rain causes severe flooding. The problem has been exacerbated in recent years by intensive developments on natural flood plains.
Since 1997, we have implemented a comprehensive flood prevention strategy that is based on the large scale river training works for main watercourses and the village flood protection scheme for low-lying villages. The Government has committed considerable resources to implement these projects in order to reduce the livelihood of rivers overflowing their banks. Most river training works include the widening, deepening and straightening of existing rivers.
In addition to river training projects, there are 27 village flood pumping schemes operating very successfully to protect low-lying villages that are at levels below the water levels in the drainage channels. | | | | Q2 After the completion of the river training schemes, will there be no more flooding in the NT? top | | | Upon the completion of the major river training schemes, the flooding situation in most areas of the NT will improve significantly. Nevertheless, there may still be minor flooding in some extremely low-lying agricultural lands but both the frequency and severity will be much reduced.
It should be made clear that flooding is a natural phenomenon and, therefore, it is not possible to eliminate the flooding risk absolutely. Instead, it is necessary to determine a set of flood protection standards for the planning and design of the drainage system.
| | | | Q3 Regulation of Shenzhen Stage III has completed in April 2007. Will the flooding problem on both sides of Shenzhen River become part of the history? top | | |
The Project of Regulation of Shenzhen River consisted of three stages and mainly involved straightening, widening and deepening the 18-km river channel. The first two stages were completed in 1997 and 2000 respectively. The third stage of the works mainly involved the widening and deepening of the 4-km long section upstream of the Liu Pok bend to the confluence with Ping Yuen River, together with the reconstruction of Lo Wu Railway Bridge, Lo Wu Old Pedestrian Bridge, Man Kam To Vehicular Bridges and two Dongjing Water Main. Coupled with the regulation of Ping Yuen River on Hong Kong side, the completion of the third stage of works has resolved the flooding problem in Ta Kwu Ling area. The discharge from Shenzhen Reservoir will no longer lead to flooding. The flooding protection standard of the trained river channel has been raised to one in 50 years return period. It is believed that the experience of waist-deep flooding on both sides of Shenzhen River during rainstorm will become part of history.
| | | | | Q4 Are there any short-term measures to provide interim relief to the flooding in New Territories before completion of these river training schemes? top | | | The Government will do everything within its power to reduce flooding. Apart from major river training projects, many other works are being carried out on a local scale that will reduce flooding or help villagers avoid flood losses. Examples are:
(i) Carrying out local drainage improvement projects
(ii) Carrying out constant maintenance and cleansing of existing stream courses and drainage systems.
(iii) Flood warning systems (flood sirens) are in operation at flood prone villages.
(iv) Installing river gauges at the critical rivers for measuring the water depth of the rivers.
| | | | Q5 Will the victims of flooding in the flood-prone areas in the NT be offered compassionate re-housing? top | | | Upon completion of the river training projects in the NT in 2005, most areas will no longer be subjected to flooding. Only limited scattered houses within flood plains will still be affected by minor localized flooding. Regarding the flooding problem to these isolated houses, re-housing is one of the options being considered by the Government. However, this is a complicated issue as the Government has to be fair to those on the general waiting list of re-housing.
Nevertheless, some flood prone areas within the project limit of the major river training works will be vacated for the implementation of the projects. | | | | Q6 What can the Government do to safeguard the flood-prone areas in the NT from possible flood damage due to discharge from the Shenzhen Reservoir? top | | | We have an agreement with the Shenzhen Authority for notification of discharge from the Shenzhen Reservoir. Under normal circumstances, the Shenzhen Authority will inform HKSAR in advance of the discharge. In case of abnormal heavy rainfall that results in sudden surge of water level in the Shenzhen Reservoir and requires urgent discharge, notification will be given as quickly as possible.
Flood warning systems have been installed to alert local villagers where there is possible flooding in the NT. When being alerted to a possible discharge, relevant government departments will stand ready to assist any villagers in need.
A number of major river training projects in the NNT are currently under construction and, upon completion, will effect considerable improvements. In particular, the Shenzhen River Regulation Project was designed to take into account of the discharge. | | | | Q7 Some Green Groups called on the Government to take steps to stop destruction and degradation of natural stream courses. What will the Government do to protect these special species? top | | | An environmental impact assessment (EIA) would be conducted for all river training works contracts. The study would identify necessary environmental protections and ecological mitigation measures. They generally include:
(a) unlined channel bed to enable re-colonisation of flora and fauna after the completion of works;
(b) use of grasscrete lining at channel sides and base to provide medium ecological value habitat for invertebrates and higher fauna;
(c) re-vegetation of embankment slopes;
(d) planting of mangroves along certain sections of channel embankments such as in Yuen Long and Kam Tin drainage channels;
(e) provision of engineered wetland/marschcrete areas to provide medium to high ecological value habitat; and
(f) keeping existing meander or original rivers wet by not blocking its connection with the trained rivers after river straightening works to maintain wetland for aquatic lives.
| | | | |  | | | | Flood Prevention in Urban Areas | | | | Q1 What are carried out to eliminate flooding in Mong Kok? top | | | | To solve the flooding problem in Mong Kok, a comprehensive drainage improvement programme at over $3.6 billion have been implemented in stages. The Drainage Services Department has implemented Stage 1 of the West Kowloon Drainage Improvement Scheme in1998. A total of about 10 kilometres of stormwater drains in Yau Ma Tei, Kowloon Tong, Sham Shui Po and Lai Chai Kok have been enlarged or replaced in 2003. Stage 2 and Stage 3 under Phase 1 of the improvement scheme include on-line improvements of 34 kilometres of stormwater drains in Tsim Sha Tsui, Yau Ma Tei, Sham Shui Po and Lai Chi Kok. The Stage 2 works also include the construction of the Tai Hang Tung Flood Storage Scheme and the Kai Tak Transfer Scheme, both completed in 2004. | | | | Q2 What are carried out to alleviate the flooding problem in Sheung Wan around Wing Lok Street? top | | | To resolve the flooding problem in the Sheung Wan low-lying area, we have implemented about $200 million in 3 phases. The project comprises the construction of intercepting drains along Queen's Road Central and a stormwater pumping station at waterfront.
About 660 m of stormwater drains were constructed along Queen's Road Central to reduce about 30% of stormwater entering this low-lyng area from the upland catchment. Construction of an underground storage tank with a pumping station is to cope with the flood water accumulated at the low-lying area in Sheung Wan. The whole project was completed in end 2009.
The flood protection level in the low-lying area in Sheung Wan is raised to withstand a rainstorm with a return period of one in 50 year upon completion of the projects.
| | | | Q3 DSD has commenced implementation of 3 large drainage tunnels in Tsuen Wan, Lai Chi Kok and Hong Kong West. Can you let me know their implementation programme? top | | | We are constructing 3 drainage tunnels including the Hong Kong Island West Drainage Tunnel, the Tsuen Wan Drainage Tunnel and the Lai Chi Kok Transfer Scheme (LCKTS).
To improve the flooding situation in Northern Hong Kong, a 11 km long Hong Kong Island West Drainage Tunnel, with diameters ranging from 6.25 m to 7.25 m, is being constructed in mid-level of Hong Kong Island. Valued at HK$3 billion, works are started in end 2007 for completion in 2012.
The Tsuen Wan Drainage Tunnel is 5.1 km long with diameter of 6.5 m. It will collect stormwater via 3 intakes located at Kwai Chung, Lo Wai and Tso Kung Tam, Tsuen Wan, and divert flow of upper catchment areas to Yau Kom Tau for discharge. Valued at about HK1 billion, works are started in end 2007 for completion in 2013.
Under the LCKTS, a total of 3.7km of drainage tunnel with diameter of 4.9 m, 6 intakes, 1 stilling basin, 1 outfall structure with pumping facilities and about 180 m of collector channels are being constructed. Works are started in early 2008 for completion in 2012.
| | | | Q4 IlIegal discharge and dumping of construction wastes into public drains is considered to be one of the causes of flooding. What measures are being implemented by the Government to tackle the problems? top | | | | Some localized flooding is caused by blockage of roadside gullies in highly populated areas or indiscriminate disposal of wastes from construction sites. Before each rainy season, we remind the personnel in charge of construction sites to exercise strict control on their construction activities. We continue to maintain close liaison with other relevant departments in this respect. Memoranda are sent to all Government works departments seeking their support in taking active measures in their construction sites to ensure that there will be no adverse drainage impact on the stormwater drainage system due to construction activities. | | | | | | | |
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