LAND, PUBLIC WORKS AND UTILITIES
From 1990 to 1998, about 260 million cubic metres of marine fill (15 per cent from nearby regions in China) and 170 million cubic metres of land-based fill were used for reclamation projects. It is expected that a further 400 million cubic metres of fill will be required to meet the need for land for housing and infrastructure developments in Hong Kong over the next decade.
The CED managed the mud-disposal facilities. During the year, about 6 million cubic metres of uncontaminated mud generated from various projects were disposed of in open sea floor disposal grounds and in exhausted marine sand borrow pits; about 3 million cubic metres of contaminated mud were placed in the purpose- dredged seabed pits at East Sha Chau. An empty marine sand borrow pit in East Sha Chau for contained disposal of contaminated mud came into operation in late-1997.
The Public Filling Sub-Committee of the FMC co-ordinated the public filling activities for beneficial use of construction and demolition debris. During the year, about 5.2 million cubic metres of public fill were used in reclamations.
In connection with the management of Hong Kong's fill resources and mud- disposal capacity, the CED, on behalf of the FMC, continued to undertake a series of geotechnical, environmental and ecological studies to examine the effects of the dredging and disposal activities, and to investigate possible ways to avoid or minimise adverse effects on the marine environment.
Hydraulic Studies
Large reclamation projects may affect the flow of water, sediment transport and wave activity in the harbour. To minimise any adverse effects, the CED employs sophisticated hydraulic models to analyse the likely effects of proposed schemes and check that they are within acceptable limits. The models are used for reclamation layout planning, design of marine structures, waterway studies and assessment of future maintenance dredging requirements. The models comprise computer-based mathematical models and a large physical model housed in the Harbour Hydraulics Laboratory at Tuen Mun.
In 1998, in order to meet the requirements for comprehensive assessments of impacts on the harbour arising from the large reclamation projects being planned, the CED completed the enhancement of the physical and mathematical models to improve their predictive capacity.
Several hydraulic studies was carried out to investigate the impact of major coastal engineering projects. These included the Green Island Reclamation, Tonggu Waterway, and Siu Lam Typhoon Shelter. A new type of seawall capable of absorbing wave energy was developed for trial to improve the wave conditions in the inner part of the Victoria Harbour.
Water Supplies
Water from Guangdong
Guangdong rivers are Hong Kong's major source of water, and will meet all future increases in demand. This arrangement dates from 1960, when a scheme was formulated for receiving a piped supply of 22.7 million cubic metres a year.
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