As there is land surveying on land, there is hydrographic surveying at sea, though many of us may not be familiar with it. Unlike other sections of the Marine Department, the Hong Kong Hydrographic Office (HKHO) has been put directly under the Development Bureau instead of the Transport and Housing Bureau ever since its inception. Hong Kong is one of the busiest ports in the world. In the context of navigational safety, the HKHO carries out hydrographic surveys in Hong Kong waters regularly to gather relevant data including water depths and seabed nature and other navigational information to produce up-to-date nautical charts and publications, as well as providing useful nautical information for port users. Today, I have invited Mr Michael CHAU who is a Principal Marine Officer and Hydrographer to share with us the work of the HKHO.

At present, the HKHO has an establishment of more than 40 permanent staff members in its surveying and charting sections. As an associate member of the International Maritime organisation, Hong Kong needs the HKHO to carry out a wide range of duties, including acquisition, collation and management of hydrographic data; printing, publication and updating of nautical charts and other publications; provision of correction service for the Differential Global Positioning System to improve accuracy of the positioning service for vessels; the search for wrecks or other submerged objects, as well as coordination with the Marine Department in removing marine mud and sediment in the fairways.

There are three hydrographic survey vessels in the HKHO responsible for carrying out hydrographic surveying work. All three vessels are equipped with various advanced survey instruments including the “multi-beam Echo Sounder”, the “satellite signal receiver” and the “motion sensor”. Every day, colleagues of the HKHO carry out hydrographic surveying in different areas of Hong Kong waters in accordance with survey plans to acquire and collate bathymetry data, which will then be used to produce the latest nautical charts and other publications.

Mr Michael CHAU told us that about 90 percent of goods and 9 percent of visitors were passed in and out of Hong Kong by sea in 2016. With the aid of the nautical charts, publications and maritime information offered by the HKHO, and the vessel traffic services (VTS) provided by the Vessel Traffic Centre of the Marine Department, these cargo or passenger ships, big or small, can rest assured that they will be guided to the safest and most convenient fairways through Hong Kong waters.

Future work to keep abreast of time

Given the development of the Global Positioning System, technological advancement in the acquisition of bathymetry data, improvement in the geographic information system and the transition from paper nautical charts to electronic navigational charts, the data handled by the HKHO is not limited to facilitating the publication of nautical charts. Rather, the data plays a critical role in many other fields such as environmental protection, designation of marine parks, shore management, delineation of maritime boundaries and even prevention of disasters as in mock tsunami and flooding drills. As we proceed with the various major infrastructural projects in Hong Kong waters, the data collected by the HKHO will play an even more important role in the planning for the area. The International Hydrographic Organisation too, is moving towards this direction. It is now working on the next generation of transfer standard for hydrographic data, such as that for electronic navigational charts. Obviously, our work in the future is getting more and more important.

Old nautical charts witnessing the changes in Hong Kong

Another thing worth sharing is that the HKHO has kept some old and valuable nautical charts of the Hong Kong waters. Mr Michael CHAU said some of these charts can be traced back to more than a century ago to the early years of Hong Kong. At present, most of these handmade charts have been scanned to digital files for preservation. These archival documents have recorded the changes of Hong Kong’s coastlines and ports over the past century, reflecting the territory's pace of development at different times.

Provision of real-time tidal data

As for collection of maritime information, the HKHO has set up four tide gauge stations across the territory, together with the tide gauges managed by the Hong Kong Observatory and the Airport Authority, this network of tide gauge stations will collect and release real-time tidal data for Hong Kong. Besides, the HKHO also measures and analyses tidal stream in Hong Kong waters regularly, based on a set of Hong Kong tidal stream prediction model, and releases information about tidal stream predictions for reference of Hong Kong citizens and vessel operators in the course of their navigation, engineering studies and more.

In recent years, amidst the rapid development of information technology, the Internet and positioning services, both Mr Michael CHAU and I have witnessed radical changes in hydrographic surveying technology, navigational skills and management of the harbour. For example, the Hong Kong electronic navigational chart first developed more than ten years ago has now become an essential tool for ocean going vessels entering the waters of Hong Kong while paper nautical charts are being relegated to the background as navigational skills have entered a new era. I hope the HKHO will continue to make good use of the Internet platform to provide high quality hydrographic surveying services to different users.