Multibeam Bathymetry surveys allow us to measure the depth of a water body and map the underwater features. Multiple methods can be used for bathymetric surveys, including multi-beam and single-beam surveys, ADCPs, sub-bottom profilers, and the Ecomapper Autonomous Underwater Vehicle. You use bathymetric surveys for many different types of research, including flood inundation, the contour of streams and reservoirs, leakage, scour and stabilization, water-quality studies, dam removal, biological and spill, and storage and fill in reservoirs and ponds.
Multibeam Bathymetry survey is a multibeam echo sounder attached to a boat that sends out a wide array of beams across a “swath” of the water body floor. As the beams are bounced back from the waterbody floor, the data is collected and processed. The processed data can be viewed in real-time on the boat during the survey. Multibeam surveying is generally done in larger water bodies.
You can use Multibeam Bathymetric Surveys for many different types of research:
- flood inundation
- the contour of streams and reservoirs
- scour and stabilization
- water-quality studies
- dam removal
- biological and spill
- storage and fill in reservoirs and ponds
The Multibeam Bathymetry survey echos sounder emits several hundred measuring beams. The fan detects a strip of the seabed along with the measuring profile. From this, a digital terrain model can be created.
Depending on the depth, the multibeam bathymetry can quickly measure a wide strip across the ship on the seabed. The basic principle of the acoustic measurement is similar to that of the single beam echo sounder. With this method, a sensor integrated into the ship’s hull emits several acoustic signals in a fan and captures the signals reflected from the seafloor. The depth of the seabed is calculated from the different transit times of the signals. Several hundred data points per second are recorded simultaneously over the width of the fan. With the help of this method, a terrain model of the measured seabed is created.
The acoustic signal is refracted at the water layers due to their different density, temperature and salinity. Therefore, waterborne sound profiles are required to correct the position of the measured points on the seafloor. These are recorded with special waterborne sound velocity probes before and after the survey and attached to the data. During the survey, the high-precision positioning of the ship is carried out utilizing a satellite positioning system. The ship’s inertial navigation system, in turn, precisely records the ship’s position angles. This highly accurate information is attached to the measured data in real-time. Together, these systems guarantee high-precision position coordinates of the measured data.
The measurement of the seabed is carried out with Multibeam Bathymetry Survey, if possible covering the entire area. The profiles are selected so that the measured strips overlap at the edges to control the measurements mutually.
As the depth of the seafloor decreases, the width of the fan decreases; therefore, multibeam bathymetry is preferably used in deeper areas. However, it is hardly used in very shallow Wadden areas. There, a surface model of the tidal flats is recorded using laser scanners.
If you go through the whole blog, you will definetly know about the Multibeam Bathymetry Surveys‘ benefitsand how they are used to gather detailed information about the features on the seabed by measuring multiple depths from a single transducer array at high resolution.