LAND, PUBLIC WORKS AND UTILITIES
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was placed in specially selected and closely monitored exhausted sand borrow pits, which were then capped with uncontaminated mud on completion of filling to isolate the contaminants from the environment. The use of exhausted sand borrow pits for mud disposal is preferred as it has the dual benefits of providing much needed disposal capacity and restoring the seabed to its natural profile and state.
In connection with the management of Hong Kong's fill resources and mud disposal capacity, the CED, on behalf of the MFC, continues to undertake a series of geotechnical, environmental and ecological studies and monitoring to examine the effect of the dredging and disposal activities, and to investigate possible ways to avoid or minimise the impact on the marine environment.
Hydraulic Studies
Coastal engineering projects may affect the flow of water, sediment transport and wave activity in the harbour. The CED employs sophisticated computer hydraulic models to analyse the likely effects of proposed schemes, both during and after the construction phases, to ensure that their impacts are minimised to within acceptable limits. The models are used for reclamation layout planning, design of marine structures, waterway studies and assessment of future maintenance dredging requirements. A digital tidal stream atlas and a wave atlas were also developed by CED to provide average tidal and extreme wave information.
Construction of a trial section of wave absorbing seawall at the new waterfront of the West Kowloon Reclamation is substantially completed. It is anticipated that this new type of seawall will help reduce the reflection of waves in the inner part of Victoria Harbour.
Water Supplies
Water from Guangdong
Guangdong rivers are Hong Kong's major source of raw water. Hong Kong began to receive raw water from Guangdong when a scheme was formulated in 1960 for receiving a piped supply of 22.7 million cubic metres a year.
In 1989, a long-term agreement was concluded with the Guangdong provincial authorities for a reliable water supply. In recent years, due to heavy rainfall, coupled with the declining demand from the local industry, there has been a decrease in demand for raw water from Guangdong. The Government reached an agreement with the Guangdong provincial authorities in July 1998 whereby the annual increase stipulated in the 1989 agreement was to be reduced from 30 million cubic metres to 10 million cubic metres from 1998 to 2004. As a result, the intake in the seven years will be reduced by 560 million cubic metres, cumulatively. Under the agreement, the supply quantity for 2002 was 800 million cubic metres, rising to 820 million cubic metres in 2004, compared with the present designed maximum capacity of 1 100 million cubic metres per year. The annual supply quantity beyond 2004 will be subject to further review.
The quality of raw water from Guangdong continues to improve as a result of the efforts made by the Guangdong provincial authorities, including the commissioning of the biological nitrification plant and sediment removal in Shenzhen Reservoir, and strict enforcement of laws on pollution control. Further improvement in water quality