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Bathymetric Surveys
It is not just land above sea level that needs to be mapped and measured - but underwater land aswell. One of many key options for mapping surface below water is utilizing a bathymetric survey.

What is it?

The word "bathymetry" refers the analysis of the terrain and contours of land underwater, such as for example lakes, rivers or oceans.

Bathymetric surveys are a kind of hydrographic survey that measures the depth of water and maps out the shape of the seabed. They are able to help draw out an in depth map of the different shapes and features of the submerged terrain.

What are they used for?


Bathymetric surveys serve a number of purposes and so are useful on both small and large scales. Understanding the bathymetry of underwater terrain can reveal a lot in what happens above the top.

For example, the shape of a riverbed can influence the speed, temperature along with other characteristics of the water flowing above it. Water reacts in various ways based on the shape of the land beneath it.

Probably the most common uses for this type of survey would be to ensure safe surface or sub-surface navigation along waterways. Captains of both small river boats and large commercial ships use bathymetric surveys to look for the path they will try reach their destination safely, as the bathymetric survey shows where both shallow and deep waters are.

It is important to remember that these surveys differ from hydrographic surveys for the reason that they are much less accurate for use in safe navigation. Bathymetric surveys are a lot more detailed than hydrographic details at outlining the terrain - whereas hydrographic surveys specifically make the charts much simpler to comprehend for navigators.

How are they drawn?

Over the years, the methods used for creating bathymetric surveys have changed significantly. In the very first stages of bathymetry, simple methods such as dropping long chains or ropes into the water off of a boat were used to gauge the depth of the water and create fairly inaccurate bathymetric surveys.

This method later advanced to echosounders that were placed beneath or over the medial side of boats. The echsounder would ping a beam of sound towards the ocean floor and the amount of time it took for the sound to travel through the water, hit the seafloor and keep coming back again indicates how deep the water is (in a similar way to how pregnancy ultrasounds are created).

These days, echosounders remain the most common types of creating bathymetric surveys - however they have advanced from single-beam sounders to multibeam echosounders (MBES). These have a huge selection of very narrow beams that stretch up to 170 degrees across allowing fast, accurate coverage of the terrain.

Echosounders work alongside GPS systems. The GPS notes down the existing location utilizing a time tag simultaneously with the reading from the echosounder. These two readings can be put together to generate both a bathymetric contour map and 3-D view.

Who makes Continue reading ?

In the USA, surveys of nearly all navigatable inland waterways are performed by america Army Corps of Engineers. Ocean bathymetric surveys are generally commissioned by the National Oceanic and Atmospheric Administration.

Bathymetric surveys can be conducted making use of your own sonar equipment (which can be very expensive) or by hiring a specialist that can conduct a more specific survey for you.

Where to find

Many surveys are available for the public to gain access to cost-free - particularly of major waterways.

The National Geophysical Data Centre (NGDC) has large sums of coastal bathymetric surveys designed for public access.

Website: http://www.landsurveyorsgloucestershire.uk/best-bathymetry-survey-gloucestershire/