Vessel Mounted ADCP Survey in the Suir Estuary

Introduction to ADCP Technology

An Acoustic Doppler Current Profiler (ADCP) is an advanced tool used in hydrography and oceanography to measure water current velocities. This is a sophisticated technology that uses the Doppler effect to determine the velocity of water currents across a range of depths.

Why Vessel-Mounted ADCPs?

Traditionally, hydrographers have deployed ADCP’s from fixed frames. This increases the licensing burden and because the sensor is stationary, it only provides current speed data for a single location. However, when coupled with high accuracy GPS position and AHRS (Attitude and Heading Reference System), vessel-mounted ADCP’s has introduced a dynamic and flexible approach to capturing ocean currents. Mounted directly to our vessel, these ADCP’s offer the advantage of mobility, allowing us to gather data over extensive areas without the need for multiple installations.

Operation

The vessel mounted ADCP is fixed to the side of a survey vessel, positioned to avoid interference from the vessel’s own movements and turbulence. It emits sound waves that bounce off particulate matter—like plankton or sediment—in the water. The data collected includes the speed and direction of currents for 0.5 m long cells.

Applications in Marine Research

There is an opportunity to use ADCP technology in marine research where understanding the water movement is important, such as:

  • Calibration of hydrodynamic models to predict future water movements.
  • Studies on sediment transport and deposition.
  • Environmental impact assessments, especially in areas affected by human activities like dredging or construction.
  • Monitoring water quality and understanding the dispersal patterns of pollutants and effluents in coastal and marine ecosystems.

Case Study: Implementation of a vessel mounted ADCP in Ireland

XYZ Engineering successfully delivered a survey using this technology in the Suir Estuary. Using our survey vessel, we carried out hourly transects across the bay over a 13 hour period during spring and neap tides. XYZ also carried out all of the post-processing and visualisation to produce current speed profile heat maps. An example is reproduced below with permission from Frame Communications.

ADCP transect profile
The top plot shows the ADCP current speed. Note the faster speeds within the shipping channel of the Suir Estuary. The bottom plot shows the incoming tide moving in an opposite direction to the outgoing flow from the Suir Estuary.

Conclusion

Vessel Mounted ADCP’s represent a significant advancement in marine survey technology. ADCP’s offer a breadth of data previously unattainable with fixed ADCP’s. Get in touch with us to discuss your next current speed survey.