Open AccessAssessment of Acoustic Coherent Doppler and Cross-Correlation Techniques for Measuring Near-Bed Velocity and Suspended Sediment Profiles in the Marine Environment
Author(s) -
Kyle F. E. Betteridge,
Peter D. Thorne,
Paul S. Bell
Publication year - 2002
Publication title -
journal of atmospheric and oceanic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.774
H-Index - 124
eISSN - 1520-0426
pISSN - 0739-0572
DOI - 10.1175/1520-0426-19.3.367
Subject(s) - acoustic doppler current profiler , acoustic doppler velocimetry , doppler effect , turbulence , backscatter (email) , geology , flow velocity , sediment , sediment transport , range (aeronautics) , cross correlation , flow measurement , flow (mathematics) , acoustics , current (fluid) , laser doppler velocimetry , physics , meteorology , mechanics , materials science , geomorphology , oceanography , mathematics , mathematical analysis , blood flow , composite material , medicine , astronomy , computer science , telecommunications , wireless
The simultaneous measurement of current flow and suspended sediment concentration in the marine environment is central to the study of sediment transport processes. In view of this, two acoustic approaches for measuring flow were tested in a tidal estuary to assess their capabilities in this environment. A coherent Doppler velocity profiler and a cross-correlation velocity profiler were assessed using conventional current meters and a commercially available acoustic Doppler velocimeter. Mean velocity profiles were obtained up to a range of 1.47 m in 0.046-m range bins over a number of flood tides. The measurements compared well with the reference instruments and regression analysis produced gradients close to unity. Turbulent velocities measured with the coherent Doppler profiler were comparable with turbulent fluctuations measured with the acoustic Doppler velocimeter. The cross-correlation velocity profiler was shown to be unable to measure turbulent velocities. The backscattered signals received on the cross-correlation transducers were also used to compute the sediment concentration profiles using an explicit solution to the acoustic backscatter equation. Combining the concentration and flow measurements enabled sediment flux profiles to be obtained, the results of which compared favorably with flux measurements obtained from the conventional current meters and pumped sampling.