Evaluation of wave measurements with an acoustic Doppler current profiler

Routine monitoring of waves and currents in the nearshore region is of great interest both scientifically and to the general public because of its role in coastline erosion and its impact on recreational activities. Historically, the technology for measuring these quantities has required separate instrumentation for each, but within the last year or two, it has been shown that it is possible in shallow water to estimate both the wave height, wave direction, and current from a conventional bottom mounted, upward-looking acoustic Doppler current profiler (ADCP). Software for converting wave orbital velocity measurements from ADCPs into wave frequency and directional spectra is now becoming commercially available. The authors have taken the opportunity to evaluate the WAVES software from RD Instruments, USA, by establishing an intercomparison between wave measurements obtained with a permanently deployed 1200 kHz ADCP, an electromagnetic current meter/pressure sensor and a heave/pitch/roll buoy. They have compared the wave surface elevation and frequency-direction spectra derived from the different measurement/analyze principles and we have analyzed the inherent software limitations due to the measurement principles.