Hydorgraphic Surverying

Hong Kong is considered as one of the safest and busiest international ports where construction and maintenance of large-scale marine infrastructures for port development never stop. To align with the rapid development, land surveyors from private practice and the civil service actively participate in charting for the up-to-date seabed terrain over Hong Kong waters for navigation, construction or maintenance of marine facilities such as fairways, piers, container terminals and mooring buoys, reclamation for the provision of land and public filling area for construction and demolition waste.

Port development projects rely on accurate knowledge of bathymetry, thus, hydrographic surveying techniques such as sounding survey are inevitably required. With the continuous advancement of technology, the efficiency, effectiveness and precision of hydrographic surveying systems are improving without a break. Single beam or multi-beam echo sounding system positioned and navigated by Differential Global Positioning System (DGPS) - free correction message broadcasted by Marine Department of the HKSAR Government - becomes a standard for bathymetric survey instead of the traditional sextant and wire.

In addition to the provision of geometrical information of the seabed, the increasing demand over environmental protection and the quality of marine works push land surveyors to consider the provision of value added land/hydrographic survey services for monitoring and analysis of the hidden seabed. On top of bathymetric survey, major hydrographic survey services also include:

- Measurement of water current 
- Bottom sampling 
- Search of wreck and underwater structure 
- Determination of subaqueous filling/dredging quantities 
- Geophysical survey for the sub-seabed profiling 
- Collection of any other relevant information 

Use of Specialized Multi-beam equipment 
to detect the topography of the seabed
(Courtesy: Civil Engineering Dept., HKSAR Government)

Use of Specialised Sub-mariner Profiler equipment 
in Hydrographic Survey.
(Courtesy: Civil Engineering Dept., HKSAR Government)