A Dual-frequency Inversion Algorithm of Suspended Sediment Concentration

The Acoustic Doppler Current Profiler (ADCP) is used to measure the velocity profile in the water column. Since the intensity of the backscattered echo is recorded simultaneously, which is closely related to the suspended sediment distribution in the water, ADCP has the potential to measure the characteristic information (such as concentration, particle size, etc.) of the suspended sediment in the water. Peter D. Thorne and Daniel M. Hanes et al. proposed the correlation between the equivalent backscatter voltage and the concentration and particle size of suspended sediment. When the suspended sediment concentration is at a high level, the scattering attenuation and viscous attenuation caused by the suspended sediment will not be negligible, making the inversion process of the suspended sediment concentration a complicated process. The usual solution is to use a layer-by-layer iterative approach from near to far to invert the concentration results, which will lead to higher computational complexity. The worst thing is that when the product of the feedback attenuation coefficient and the distance is high, it will cause iteration instability, which means that the iteration no longer converges. This paper proposes a dual-frequency concentration inversion algorithm. The simulation results show that under the premise of meeting the measurement requirements, this method can effectively solve the problem of iterative instability and reduce the computational complexity.