LAND, PUBLIC WORKS AND UTILITIES
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Its main functions are to exercise control over illegal, defective, inadequate and insanitary drains and sewers in private buildings.
Survey and Mapping
The Survey and Mapping Office of the Buildings and Lands Department is mainly engaged in establishing and maintaining survey control throughout the territory as a basis for land title boundary surveys, and the production and revision of topographical mapping. Some of the other services provided include large scale basic mapping, pro- duction of special use maps, aerial photography and photogrammetry and reprographic services.
Horizontal and vertical control networks, known as geodetic control systems, have been established and maintained to a high order of accuracy. These networks provide the necessary origin for the production of cadastral (or property boundary) surveys and the all-important control for engineering surveys and topographical mapping.
Cadastral surveys in the urban areas are an ongoing requirement. Most of the work is in the definition of leasehold property boundaries, and the demarcation of land required for government purposes. In the New Territories the emphasis has shifted from the new towns to the village areas where an increasing number of boundary surveys for village house lots are being carried out. Other tasks include the re-establishment of old lot boundaries for redevelopment purposes, and the maintenance of the cadastral records that define land allocation and occupation for every region of Hong Kong.
Comprehensive map coverage of the territory is provided, ranging from the 3 000-sheet large scale basic mapping series at 1:1 000, through 1:5 000, 1:20 000 and 1:50 000 series down-to the single small scale sheets at 1:100 000 and 1:200 000. A new 1:10 000 street map series of the developed areas was completed, mainly for use in guide books and to replace the obsolete 1:7 500 sheets. Guide books, guide maps and countryside leisure series remain in high public demand, necessitating continuous action on revision and periodic redesign and replacement.
A wide range of cartographic services is also provided to other government departments. These services include preparing end-paper maps for the Hong Kong Annual Report, providing geological services for geotechnical control, and preparing base maps for other forecasting services, electoral boundary maps, country park maps, and harbour and glide path maps. Copies of monochrome services and sophisticated photo-reproduction services are also provided by the Reprographic Unit.
The Air Survey Unit operating from the Royal Hong Kong Auxiliary Air Force aircraft continued to provide aerial photographs for engineering design work, volumetric calcula- tions of quarries and reservoirs, environmental studies and large scale mapping. Processing and production of the required data continues to be carried out by the Survey and Mapping Office Photogrammetric Unit. Vertical and oblique photography has been taken using an air survey camera in a RHKAAF helicopter, and has been particularly useful for obtaining photography of dangerous slopes.
The three sets of Survey/Mapping Computers and Plotters, installed in the Hong Kong, Kowloon and Tai Po District Survey Offices, are now fully utilised, undertaking surveying calculations and producing computer activated maps and plans. Terminals from more remote District Survey Offices have been installed to link up with these three main units. The introduction of these modern 'hi-tech' installations has greatly improved efficiency.
The proposal to install a computerised Land Information System is under study.