Measurement and analysis of acoustic backscattering strength for characteristics of seafloor sediment in Indian Ocean WPP 572-573

Abstract

Understanding and predicting the acoustic backscattering from seafloor substrates was essential to support the management and development of coastal area as well as offshore. The aims of this study were to quantify the acoustic backscattering strength from the seafloor substrates, classify the types of seafloor substrates, as well as correlation between the seafloor substrates and the value of surface backscattering strength (SS). The data collection was done in April to June 2016 in the Indian Ocean WPP 572-573 using hydroacoustic instrument SIMRAD EK60 with operating frequency of 38 kHz. Substrate sampling was used for data validation using Van Veen Grab. The results showed that the SS value for the type of sand substrate (-8.05 dB to -5.25 dB), silty sand (-8.15 dB to -7.03 dB), sandy silt (-11.30 dB to -11.35 dB), silt clayey (-14.71 dB to -12.17 dB) and clay substrate -23.55 dB. Between the SS value and the sand percentage had a very strong positive correlation, and a very strong negative correlation between the surface backscattering strength and the clay percentage. In contrast, a poor negative correlation was also found between the SS value and the silt percentage.