Hydrographic surveying is the scientific determination of what lies beneath the surface of a body of water, be it the ocean, a dam or harbour. It measures all factors, including depth, thermal inclines, topography and composition. Applying the resulting data is often vital for safety and planning reasons. Astute Surveying provides comprehensive hydrographic survey services in Australia.
The Importance and Application of Hydrographic Surveying
Knowing what lies beneath the surface undoubtedly has real safety implications for ships and boats, but it also provides valuable information for other industries. Most civil engineering projects undertaken near or in water can only succeed if accurate knowledge of what lies beneath the surface is available during the planning and design phases.
The construction of roads, bridges and causeways indirectly uses the hydrographic data. For the construction of harbours, piers and channels, the data plays a direct role in assessing the viability of a project. Accurate hydrographic surveying becomes an integral component of ensuring the safety of any water located project.
Hydrographic surveying also provides the necessary information to assess the current condition of structures like dam walls and weirs. This is an important task, especially after severe storms that might compromise the integrity of artificial structures. A hydrographic survey is also undertaken to verify the depth and shape of dams, channels and harbours.
Current Methods of Hydrographic Surveying
Scientific hydrographic surveying is not new, but we have progressed a long way from a sounding line – although this is often still the best go-to method for simplistic and often shallow projects. The advent of electronics and computer processing has replaced all the analogue methods with four essential, high-accuracy hydrographic surveying methods:
• Multibeam Echosounders (MBES): This method emits multiple acoustic waves in a fan shape and uses beamforming to extract directional information. The sonar produces a swathe of depth readings from a single ping, which is immediately analysed by computers. The data can include bathymetry, acoustic backscatter and water column data. This is the most common form of data today. The 3D point clouds produced are used to generate contours and colour gradient models
• Laser Scanning: As the name implies, this method uses lasers to scan what lies beneath the surface accurately. The data is then processed and used to create 3D models of the seabed and vertical structures.
• Digital Single Beam Echo Sounding: We still use traditional single beam methods, however the echo sounders have progressed to allow the capture of the digital echogram. Having this data collected at the time of survey allows the hydrographic surveyor to reprocess the data and make those critical decisions the computer is unable to do. Coupled with an accurate RTK GNSS delivers accurate positioning and compensates for any heave movements on the water.
• Side Scan Sonar: Side Scan Sonars have been traditionally used in conjunction with the single beam echo sounder to deliver a monochrome image of the seabed. This data was analysed for any objects or obstructions that may have been missed by the single beam. Today we still the Side Scan Sonar for object detection and also seabed identification/material properties. The main benefit over the Multibeam is the large seabed coverage and resolution of the images/mosaics.
Contact Astute Surveying
If you find yourself wondering, “what is a hydrographic survey”? - Astute Surveying has the information you need because we do it best and we own our equipment. We regularly work in conjunction with harbour authorities and assist with analysing water supply dams.
Contact us for accurate hydrographic surveys in New South Wales, Queensland, Victoria and Australia wide.