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What is the difference between hydrographic and bathymetric surveys?

Bathymetric and Hydrographic are terms that both refer to marine topography and are often used interchangeably. However, when it comes to bathymetric surveys and hydrographic surveys, there are differences to take into consideration, with bathymetric surveys being a form of hydrographic survey that typically provide a more detailed topology of the bottom surface.

Other types of hydrographic surveys include harbour surveys, passage surveys, coastal surveys, and general hydrographic surveys for correction. Whilst hydrography covers bathymetry, it also includes the shape and features of the properties of the water itself, and the characteristics of surrounding shorelines in terms of tides, currents, and waves.

What are hydrographic surveys?

Also known as underwater surveying, hydrography is the science that measures and determines the physical features of bodies of water and the adjacent land areas. As previously identified, the key features being studied include the depth of water, topographic features of the surrounding shoreline. There are many practical uses for understanding the contortions and elevations of the ocean floor, with the main one being the safety of maritime transportation. Mapping out water depths, potential obstructions, the shape of the coastline of waterbodies allows maritime navigation, marine construction, oil and gas drilling and dredging to occur safely and efficiently.

What are bathymetric surveys?

Bathymetric surveys are a type of hydrographic survey which are used to map out the details of underwater terrain, by illustrating the land that lies beneath a body of water and the depth of the water. Bathymetric surveys can be used to collect data for a variety of water bodies, such as rivers and lakes, with the purpose of informing flood assessments and potential project developments.

Bathymetric surveyors typically use an echo sounder attached to a survey boat to conduct the survey. The echo sounder generates electrical signals whilst the boat moves across the water, with these signals then being converted into sound waves by an under-water transducer. As the soundwaves bounce off under-water features, the echo is identified by an echosounder to calculate the distances, with each of these distances being linked to a surveying map using a GNSS. The final stage involves transforming captured data into an elevated model.

Landform Surveys

Amongst our other areas of expertise, Landform Surveys are expert hydrographic surveyors, providing bathymetric surveys for clients across the North East. Using the most up to date technology, our surveyors have conducted bathymetric surveys to help our clients for a variety of needs, from cross sections over wide, deep rivers to mapping depths over large mud flats.

If you’re looking for a bathymetric survey or want to talk through other survey options that are more suited to your project, then be sure to get in touch with our specialist surveyors today.