ENG-1993 — Page 266

LAND, PUBLIC WORKS AND UTILITIES

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Geodetic control systems, which are horizontal and vertical control networks covering the whole territory, have been established and are maintained to a high degree of accuracy. These systems provide the necessary origin and control points for cadastral (property boundary), topographical mapping, engineering and other surveys.

Cadastral surveying is one of the more important functions of the office, defining land boundaries for disposal and redevelopment, among other administrative purposes. The office maintains a comprehensive record of all leasehold and government land boundaries in the territory, with most urban area records stored in digital form and the New Territories records kept in graphical form.

The office's mapping coverage of Hong Kong is extensive. The most definitive series of maps and the foundation of all other mapping is the large-scale (1:1 000) basic topographic series (3 000 sheets). Smaller-scaled maps include the monochrome map series at 1:5 000 (157 sheets) and the coloured map series at 1:20 000 (16 sheets). Two monochrome street map series at 1:10 000 and 1:15 000 of the urban areas in Hong Kong, Kowloon and parts of the New Territories are produced for special uses and as a base for the popular guide-book Hong Kong GuideStreets and Places. Demand for leisure maps, in the form of the Countryside Series and the Tourist Guide, is strong.

The Survey and Mapping Office provides cartographic services for many government departments. These include full-colour mapping for geological purposes, base maps for weather forecasting, aeronautical charts, electoral boundary maps and pollution control plans.

Its Reprographic Unit also provides services in photo-reproduction and plan copying, and serves as an essential back-up for in-house map reduction and other cartographic activities.

A computerised land information system is being installed in District Survey Offices in phases, as digital map data and land records become available. The system processes and analyses land information, and is a useful tool for handling enquiries on land status. The system also automates the production of large-scale maps and cadastral plans. Up-to-date mapping and boundary information can be made readily available to users. Besides producing standard 1:1 000 survey sheets containing full topographical features, the system can also produce plans according to the user's specifications. Mapping information in digital form may be supplied to the public on payment of a fee. Direct on-line access to the central mapping data is also possible. Data conversion for the districts is being speeded up by contracting-out the work and is scheduled for completion in 1994.

The office's Photogrammetric Survey Section provides aerial photographs and photogrammetric mapping, as well as data for engineering design work, environmental studies and town planning work, and volumetric calculations for quarry and controlled tipping operations. The Air Survey Unit is also on call for quick response photography in emergency operations such as storms, flooding and landslips.

Drainage Services

The Drainage Services Department is committed to a programme of works to upgrade Hong Kong's drainage systems to significantly reduce water pollution and flooding as far as possible, at an estimated cost of some $20 billion over the next 10 years.

It is responsible for planning, designing, constructing, operating and maintaining the sewerage, sewage treatment and stormwater drainage infrastructures.