TRANSPORT CHARACTERISTICS OF SUSPENDED SEDIMENT ON MUD FLAT IN A TIDAL CHANNEL

Acoustic Doppler current profilers (aDcps) offer the potential for measuring suspended sediment concentration profiles. In recent years, aDcps operating at a few megahertz frequency have been able to measure velocity and backscattered signal profiles with a high degree of temporal and spatial resolution. Moreover, the blanking distance near the transducer becomes short. As a result, the aDcps may attain high-resolution measurements of suspended sediments in the bottom 1-2 m above the bed. However, a modification needs to be made to account for the complex beam pattern close to the transducer (near-field). In the present study, the backscattered signal of an aDcp operating at 2 MHz is examined. The backscattered signal profiles corrected using the near-field function by Thorne give close agreement with suspended sediment concentration profiles on the tidal flat in an estuary.